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WO2013157495A1 - Organic electroluminescence element and production method for organic electroluminescence element - Google Patents

Organic electroluminescence element and production method for organic electroluminescence element Download PDF

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WO2013157495A1
WO2013157495A1 PCT/JP2013/061055 JP2013061055W WO2013157495A1 WO 2013157495 A1 WO2013157495 A1 WO 2013157495A1 JP 2013061055 W JP2013061055 W JP 2013061055W WO 2013157495 A1 WO2013157495 A1 WO 2013157495A1
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organic
ring
range
light emitting
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PCT/JP2013/061055
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French (fr)
Japanese (ja)
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大久保　康
秀雄 ▲高▼
貴宗 服部
池水　大
貴之 飯島
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コニカミノルタ株式会社
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Priority to JP2014511196A priority Critical patent/JP6168050B2/en
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Definitions

  • the present invention relates to an organic electroluminescence device and a method for producing the same, and more particularly to an organic electroluminescence device having improved light emission efficiency, light emission lifetime and color rendering properties and a method for producing the same.
  • organic electroluminescence elements using organic materials are promising for use as solid light-emitting, lightweight, thin, and inexpensive large-area full-color display elements and writing light source arrays. Research and development is actively underway.
  • the organic EL element is a thin film type having a single layer configuration or a multilayer configuration of an organic functional layer containing an organic light-emitting substance and having a thickness of only about 0.1 ⁇ m between a pair of anode and cathode formed on a film. It is an all-solid-state device.
  • a relatively low voltage of about 2 to 20 V is applied to such an organic EL element, electrons are injected from the cathode and holes are injected from the anode into the organic compound layer. It is known that light emission can be obtained by releasing energy as light when these electrons and holes recombine in the light emitting layer and the formed excitons return to the ground state. It is a technology expected as a lighting device.
  • organic EL device that utilizes phosphorescence can in principle achieve a luminous efficiency that is approximately four times that of conventional methods that utilize fluorescence.
  • Research and development of organic functional layers and electrodes are being conducted all over the world.
  • application to lighting fixtures which account for a large proportion of human energy consumption, has begun to be studied.
  • white light-emitting panels that can replace conventional lighting fixtures, There are many attempts to improve and reduce costs.
  • the white light emitting panel for illumination is required to have high efficiency and long life, but in terms of extending the life, in particular, the performance is insufficient with respect to fluorescent lamps and white LEDs. There is a demand for the development of technologies for improving efficiency and extending the service life. In addition, a light-emitting material having a sharp spectrum is also required for controlling the color temperature.
  • Quantum dot material is not only a sharp emission spectrum but also an inorganic material, so it has excellent durability and can be dispersed in various solvents, so it can be applied to wet coating methods.
  • Non-Patent Document 1 a red quantum dot material is represented by N, N′-diphenyl-N, N′-bis (3-methylphenyl)-(1,1′biphenyl) -4,4′-diamine. It has been reported that red light emission having a sharp spectrum was confirmed in an element formed by dispersing and spin coating. However, the luminous efficiency obtained was as low as about 1 lm / W.
  • Patent Document 1 discloses a method of obtaining a blue light emitting element using blue quantum dots, but a driving voltage of about 11 V is necessary to obtain a brightness of 300 cd. However, a light-emitting element using a blue quantum dot with high efficiency has not been obtained yet. This is presumably because the host material that injects charges into the quantum dots has a low charge transport property and the level is not matched, so the efficiency of charge injection into the quantum dots is low.
  • Patent Document 2 discloses an organic EL element in which 4,4′-bis (carbazol-9-yl) biphenyl, which is known as a good host material in a phosphorescent organic EL element, is combined with a red light emitting quantum dot.
  • Patent Document 3 discloses an organic EL device in which 4,4′-bis (carbazol-9-yl) -9,9-dimethylfluorene is used as a host material and is combined with green light emitting quantum dots.
  • 4,4′-bis (carbazol-9-yl) -9,9-dimethylfluorene is used as a host material and is combined with green light emitting quantum dots.
  • a blue light-emitting organic EL element using blue light-emitting quantum dots which is excellent in light emission efficiency and element lifetime, and a high color rendering property
  • the device is not yet realized.
  • the present invention has been made in view of the above problems, and its solution is to provide an organic electroluminescence device having a high luminous efficiency and a long lifetime and a method for producing the same, and particularly excellent in color rendering. To provide a white light-emitting organic electroluminescence device having stable chromaticity even at a low driving voltage and a method for manufacturing the same.
  • the present inventor is an organic electroluminescence device having at least an anode, a hole transport layer, a light emitting layer containing a phosphorescent compound, an electron transport layer, and a cathode. And an organic electroluminescence device having a light-emitting layer comprising a quantum dot having a light emission wavelength in a specific range and a host compound having a light emission wavelength belonging to a 0-0 transition band in the phosphorescence spectrum in a specific range Thus, it has been found that a white light-emitting organic electroluminescent element having high luminous efficiency and long life, excellent color rendering properties, and stable chromaticity even at a low driving voltage can be realized.
  • An organic electroluminescence device having at least an anode, a hole transport layer, a light emitting layer containing a phosphorescent compound, an electron transport layer and a cathode,
  • the light-emitting layer contains quantum dots having an emission wavelength in the range of 413 to 477 nm and a host compound having an emission wavelength in the range of 413 to 459 nm attributed to the 0-0 transition band in the phosphorescence spectrum.
  • the quantum dot is composed of at least Si, Ge, GaN, GaP, CdS, CdSe, CdTe, InP, InN, ZnS, In 2 S 3 , ZnO, CdO, or a mixture thereof.
  • the organic electroluminescent element according to any one of items 1 to 3.
  • Item 5 The organic electroluminescence device according to any one of Items 1 to 4, wherein the host compound has a molecular weight in the range of 500 to 1,000.
  • the said light emitting layer contains the compound represented by following General formula (1) as said host compound, The organic electroluminescent element as described in any one of Claim 1-5 characterized by the above-mentioned.
  • X represents NR ′, an oxygen atom, a sulfur atom, CR′R ′′, or SiR′R ′′.
  • y 1 and y 2 each represent CR ′ or a nitrogen atom.
  • R ′ and R ′′ each represent a hydrogen atom or a substituent.
  • Ar 1 and Ar 2 each represent an aromatic ring, which may be the same or different.
  • N represents an integer of 0 to 4.] 7).
  • X in the said General formula (1) is an oxygen atom,
  • Ar 3 to Ar 5 each represents an aromatic ring and may be the same or different from each other.
  • n1 represents an integer of 0 to 4
  • n2 represents an integer of 0 to 5.
  • Items 1 to 9 characterized in that the light emitting layer further contains a phosphorescent dopant whose emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum is in the range of 496 to 827 nm.
  • the organic electroluminescent element as described in any one of the above.
  • At least an anode, a hole transport layer, a light emitting layer containing a phosphorescent compound, an electron transport layer and a method for producing an organic electroluminescent device having a cathode contains a quantum dot having an emission wavelength in the range of 413 to 477 nm and a host compound having an emission wavelength belonging to the 0-0 transition band in the phosphorescence spectrum in the range of 413 to 459 nm.
  • a method for producing an organic electroluminescence device wherein the light emitting layer is formed by a coating method, and a solvent having a boiling point in the range of 100 to 150 ° C. is contained in the coating solution for forming a light emitting layer.
  • the quantum dots having an emission wavelength in the range of 413 to 477 nm and the emission attributed to the 0-0 transition band in the phosphorescence spectrum By using a host compound having a wavelength in the range of 413 to 459 nm, it becomes possible to efficiently inject excitons into the quantum dots, and as a result, high luminous efficiency can be obtained, and due to non-luminescent processes. As a result of suppressing damage to the thermal light-emitting element, an organic EL element having high efficiency and a long life can be provided.
  • the organic electroluminescence device of the present invention has at least an anode, a hole transport layer, a light emitting layer containing a phosphorescent compound, an electron transport layer and a cathode, and the light emitting layer has an emission wavelength of 413 to 477 nm. Characterized in that it contains a quantum dot in the range and a host compound in which the emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum is in the range of 413 to 459 nm, and has high luminous efficiency and long lifetime. In addition, it is possible to realize a white light-emitting organic electroluminescence element that is excellent in color rendering and stable in chromaticity even at a low driving voltage. This feature is a technical feature common to the inventions according to claims 1 to 11.
  • the quantum dot has an average particle diameter as a characteristic of a quantum dot having an emission wavelength in the range of 413 to 477 nm according to the present invention. It is preferably in the range of 1 to 20 nm.
  • the aspect ratio (major axis diameter / minor axis diameter) of the quantum dots is preferably in the range of 1.0 to 2.0.
  • the quantum dots to be applied are preferably composed of at least Si, Ge, GaN, GaP, CdS, CdSe, CdTe, InP, InN, ZnS, In 2 S 3 , ZnO, CdO, or a mixture thereof.
  • the host compound having an emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum according to the present invention in the range of 413 to 459 nm should have a molecular weight of the host compound in the range of 500 to 1000. Is preferred.
  • a light emitting layer contains the compound represented by the said General formula (1) as a host compound.
  • X is preferably NR ′ or an oxygen atom.
  • the compound represented by the general formula (1) is a compound represented by the general formula (2).
  • the light emitting layer constituting the organic EL device of the present invention may further contain a phosphorescent dopant whose emission wavelength belonging to the 0-0 transition band in the phosphorescence spectrum is in the range of 496 to 827 nm. preferable.
  • the light emitting layer is formed by a coating method, and the coating liquid for forming the light emitting layer contains a solvent having a boiling point in the range of 100 to 150 ° C. It is characterized by.
  • a “quantum dot” is a semiconductor microcrystal having a diameter of several to several tens of nm formed to confine electrons (and holes) in a minute space, and exhibits a quantum size effect. It refers to microcrystals.
  • band gap of quantum dots refers to the energy difference (energy gap) between the valence band and the conduction band of the quantum dots.
  • Bin gaps of host compounds, phosphorescent dopants, etc. mean the energy difference (energy gap) between the energy level of the highest occupied molecular orbital (HOMO) and the energy level of the lowest unoccupied molecular orbital (LUMO).
  • the quantum dots according to the present invention are characterized in that the emission wavelength is in the range of 413 to 477 nm, but in the band gap, it is in the range of 2.6 to 3.0 eV.
  • the host compound according to the present invention is characterized in that the emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum is in the range of 413 to 459 nm. Within the range of ⁇ 3.0 eV.
  • ⁇ is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
  • FIG. 1 the schematic sectional drawing which shows an example of a structure of the organic electroluminescent element of this invention is shown.
  • an organic EL device 100 has a flexible support substrate 1.
  • An anode 2 is formed on the flexible support substrate 1
  • an organic functional layer 20 is formed on the anode 2
  • a cathode 8 is formed on the organic functional layer 20.
  • the organic functional layer 20 refers to each layer constituting the organic EL element 100 provided between the anode 2 and the cathode 8.
  • the organic functional layer 20 includes, for example, a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, an electron injection layer 7, and in addition, a hole block layer, an electron block layer, and the like. May be included.
  • the anode 2, the organic functional layer 20, and the cathode 8 on the flexible support substrate 1 are sealed with a flexible sealing member 10 through a sealing adhesive 9.
  • these layer structures (refer FIG. 1) of the organic EL element 100 show an example of a preferable organic EL element EL element structure, and this invention is not limited only to the structure illustrated in FIG.
  • Other typical configurations of the organic EL device of the present invention include, for example, layer structures as exemplified in the following (i) to (viii).
  • an injection layer can be provided as necessary.
  • the injection layer there are a hole injection layer and an electron injection layer.
  • the injection layer may exist between the anode and the light emitting layer or the hole transport layer, and between the cathode and the light emitting layer or the electron transport layer.
  • the injection layer referred to in the present invention is a layer provided between the electrode and the organic functional layer in order to lower the driving voltage and improve the light emission luminance.
  • Injection materials include triazole derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives.
  • a metal buffer layer an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide.
  • the buffer layer is desirably a very thin film, preferably potassium fluoride or sodium fluoride, and has a film thickness of about 0.1 nm to 5 ⁇ m, preferably 0.8.
  • the thickness is 1 to 100 nm, more preferably 0.5 to 10 nm, and most preferably 0.5 to 4 nm.
  • the hole transport layer is made of a material having a function of transporting holes, and has a function of transmitting holes injected from the anode to the light emitting layer. Good.
  • the total film thickness of the hole transport layer of the present invention is not particularly limited, but is usually in the range of 5 nm to 5 ⁇ m, more preferably in the range of 2 to 500 nm, and still more preferably in the range of 5 to 200 nm. Is within.
  • a material used for the hole transport layer (hereinafter referred to as a hole transport material), any material that has either a hole injection property or a transport property or an electron barrier property may be used. Any one can be selected and used.
  • porphyrin derivatives for example, porphyrin derivatives, phthalocyanine derivatives, oxazole derivatives, oxadiazole derivatives, triazole derivatives, imidazole derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, hydrazone derivatives, stilbene derivatives, polyarylalkane derivatives, triarylamine derivatives, carbazole derivatives , Indolocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polyvinyl carbazole, polymer materials or oligomers with aromatic amines introduced into the main chain or side chain, polysilane, conductive Polymer or oligomer (eg, PEDOT: PSS (poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate) ),
  • Examples of the triarylamine derivative include benzidine type represented by ⁇ -NPD (4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl), and MTDATA (4,4 ′, 4 ′′).
  • Examples include a starburst type represented by -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine), a compound having fluorene or anthracene in the triarylamine-linked core.
  • hexaazatriphenylene derivatives such as those described in JP-T-2003-519432 and JP-A-2006-135145 can also be used as a hole transport material.
  • a hole transport layer having a high p property doped with impurities can also be used.
  • examples thereof include JP-A-4-297076, JP-A-2000-196140, and JP-A-2001-102175. Appl. Phys. 95, 5773 (2004), and the like.
  • JP-A-11-251067, J. Org. Huang et. al. It is also possible to use so-called p-type hole transport materials and inorganic compounds such as p-type-Si and p-type-SiC as described in the literature (Applied Physics Letters 80 (2002), p. 139). Further, ortho-metalated organometallic complexes having Ir or Pt as the central metal represented by Ir (ppy) 3 are also preferably used.
  • the above-mentioned materials can be used as the hole transport material, a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an azatriphenylene derivative, an organometallic complex, or an aromatic amine is introduced into the main chain or side chain.
  • the polymer materials or oligomers used are preferably used.
  • the hole transport material may be used alone or in combination of two or more.
  • Electron transport layer constituting the organic functional layer of the organic EL device of the present invention is composed of a material having a function of transporting electrons, and in a broad sense, the electron injection layer and the hole blocking layer are also electrons. Included in the transport layer category.
  • the electron transport layer can be provided as a single layer or a plurality of layers.
  • an electron transport material (hole blocking material) that can be applied to an electron transport layer formed at a position adjacent to the cathode side with respect to the light emitting layer
  • the material can be selected from any conventionally known compounds and used. Examples thereof include metal complexes such as fluorene derivatives, carbazole derivatives, azacarbazole derivatives, oxadiazole derivatives, triazole derivatives, silole derivatives, pyridine derivatives, pyrimidine derivatives, 8-quinolinol derivatives, and the like.
  • metal-free or metal phthalocyanine or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material.
  • carbazole derivatives azacarbazole derivatives, pyridine derivatives and the like are preferable, and among them, azacarbazole derivatives are more preferable.
  • the electron transport layer can be formed by thinning the electron transport material by a known method such as a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. It is preferably formed by a wet process using a coating solution containing a material and a fluorinated alcohol solvent.
  • the thickness of the electron transport layer is not particularly limited, but is usually in the range of 5 nm to 5 ⁇ m, preferably in the range of 5 to 200 nm.
  • the electron transport layer may have a single layer structure composed of one or more of the above materials.
  • n-type electron transport layer doped with impurities examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.
  • the electron transport layer according to the present invention preferably contains an organic alkali metal salt.
  • the type of organic substance is not particularly limited, but for example, formate, acetate, propionic acid, butyrate, valerate, caprate, enanthate, caprylate, oxalate, malonate, Succinate, benzoate, phthalate, isophthalate, terephthalate, salicylate, pyruvate, lactate, malate, adipate, mesylate, tosylate, benzenesulfonate
  • it is an alkali metal salt of an aliphatic carboxylic acid such as formate, acetate, propionate, butyrate, etc.
  • the aliphatic carboxylic acid preferably has 4 or less carbon atoms, most preferably acetate. It is.
  • the kind of alkali metal of the organic alkali metal salt is not particularly limited, and examples thereof include Na, K, and Cs, preferably K, Cs, and more preferably Cs.
  • the alkali metal salt of the organic substance include a combination of the organic substance and the alkali metal, preferably, formic acid Li, formic acid K, formic acid Na, formic acid Cs, acetic acid Li, acetic acid K, Na acetate, acetic acid Cs, propionic acid Li, Propionic acid Na, propionic acid K, propionic acid Cs, oxalic acid Li, oxalic acid Na, oxalic acid K, oxalic acid Cs, malonic acid Li, malonic acid Na, malonic acid K, malonic acid Cs, succinic acid Li, succinic acid Na, succinic acid K, succinic acid Cs, benzoic acid Li, benzoic acid Na, benzoic acid K, benzoic acid Cs, more preferably Li
  • the content of the alkali metal salt of these organic substances is preferably in the range of 1.5 to 35% by mass, more preferably in the range of 3 to 25% by mass with respect to 100% by mass of the electron transport layer to be added. Most preferably, it is in the range of 5 to 15% by mass.
  • the light-emitting layer constituting the organic EL device of the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and emits light.
  • the portion to be formed may be in the light emitting layer or at the interface between the light emitting layer and the adjacent layer.
  • the light emitting layer according to the present invention comprises a quantum dot having an emission wavelength in the range of 413 to 477 nm, and a host compound having an emission wavelength in the range of 413 to 459 nm attributed to the 0-0 transition band in the phosphorescence spectrum.
  • a quantum dot having an emission wavelength in the range of 413 to 477 nm
  • a host compound having an emission wavelength in the range of 413 to 459 nm attributed to the 0-0 transition band in the phosphorescence spectrum.
  • the total thickness of the light emitting layers is preferably in the range of 1 to 100 nm, and more preferably 50 nm or less because a lower driving voltage can be obtained.
  • the sum total of the film thickness of the light emitting layer as used in this invention means the film thickness also including the said intermediate
  • the film thickness of each light emitting layer is preferably adjusted within the range of 1 to 50 nm.
  • the individual light emitting layers may exhibit blue, green, and red light emission, and there is no particular limitation on the relationship of the film thickness of each light emitting layer.
  • a light emitting material or a host compound which will be described later, is formed by forming a film by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink jet method. it can.
  • a plurality of light emitting materials may be mixed in each light emitting layer, or a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer.
  • the light emitting layer preferably contains a host compound and a light emitting material (also referred to as a light emitting dopant compound) and emits light with the light emitting material.
  • a light emitting material also referred to as a light emitting dopant compound
  • the host compound applied to the light emitting layer constituting the organic EL device of the present invention has an emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum of 413 to 459 nm (2.7 to 3). .0 eV), a compound having a short emission wavelength, that is, a compound having a high triplet energy. More preferred are compounds having an emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum in the range of 430 to 455 nm, and more preferred are compounds having a wavelength of 440 to 450 nm.
  • the host compound according to the present invention is not particularly limited as long as it satisfies the above conditions.
  • the emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum of the host compound according to the present invention can be determined by the following method.
  • any solvent that can dissolve the host compound may be used.
  • the above-described measurement method is considered to have no problem because the solvent effect of the phosphorescence wavelength is negligible.
  • the 0-0 transition band having the maximum emission wavelength that appears on the shortest wavelength side in the phosphorescence spectrum chart obtained by the above measurement method is defined as
  • the phosphorescence spectrum is usually weak in intensity, it may become difficult to distinguish between noise and peak when enlarged.
  • the emission spectrum during excitation light irradiation (for convenience, this is referred to as a steady light spectrum) is expanded, and after the excitation light is irradiated, the emission spectrum after 100 ms (for convenience, this is referred to as a phosphorescence spectrum).
  • the 0-0 transition band can be determined by reading the peak wavelength of the phosphorescence spectrum from the stationary light spectrum portion derived from the phosphorescence spectrum.
  • a fluorometer F4500 manufactured by Hitachi High-Technology Corporation can be exemplified.
  • a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) of less than 0.1 is preferable. More preferably, the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the volume ratio in the layer is 50% or more among the compounds contained in a light emitting layer.
  • the host compound is not particularly limited as long as it is a compound having the above conditions defined in the present invention, and a known host compound may be used alone or in combination of two or more.
  • a known host compound may be used alone or in combination of two or more.
  • the host compound used in the present invention is not particularly limited as long as it is a compound having the above-mentioned conditions defined in the present invention, and may be a conventionally known low molecular compound or a high molecular compound having a repeating unit, and may be a vinyl group. Or a low molecular compound (polymerizable light-emitting host) having a polymerizable group such as an epoxy group, but when a high molecular weight material is used, the compound may take up the solvent and swell or gelate, and the solvent is unlikely to escape. In order to prevent this phenomenon, it is preferable that the molecular weight is not high.
  • a material having a molecular weight of 2000 or less at the time of coating and a material having a molecular weight of 1000 or less at the time of coating. More preferred is a host compound having a molecular weight in the range of 500 to 1000, and particularly preferred is a molecular weight of 550 to 850.
  • a host compound in ⁇ most preferably a host compound having a molecular weight in the range of 600-800.
  • the known host compound a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being increased in wavelength, and has a high Tg (glass transition temperature) is preferable.
  • the glass transition point (Tg) is a value obtained by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).
  • the host compound is preferably a compound represented by the following general formula (1). This is because the host compound represented by the following general formula (1) has a condensed ring structure, and therefore has a high carrier transport property, and also has the broad triplet energy (0-0 band of phosphorescence). preferable.
  • X represents NR ′, oxygen atom, sulfur atom, CR′R ′′, or SiR′R ′′.
  • y 1 and y 2 each represent CR ′ or a nitrogen atom.
  • R ′ and R ′′ each represent a hydrogen atom or a substituent.
  • Ar 1 and Ar 2 each represent an aromatic ring and may be the same or different.
  • N represents an integer of 0 to 4.
  • a carbazole derivative is particularly preferable.
  • examples of the substituent represented by R ′ and R ′′ include an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, t -Butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (eg, vinyl group, allyl group) Group), alkynyl group (for example, ethynyl group, propargyl group, etc.), aromatic hydrocarbon ring group (aromatic carbocyclic group, aryl group, etc.), for example, phenyl group, p-chlorophenyl
  • a compound represented by the general formula (1) is preferably a compound in which X is NR ′ or an oxygen atom. That is, a compound having a (aza) carbazole ring or a (aza) dibenzofuran ring is preferable. More preferably, it is a compound having a (aza) carbazole ring which is more excellent in electron transport property.
  • R ′ is an aromatic hydrocarbon group (also called an aromatic carbocyclic group, aryl group, etc., for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, An azulenyl group, an acenaphthenyl group, a fluorenyl group, a phenanthryl group, an indenyl group, a pyrenyl group, a biphenylyl group, or an aromatic heterocyclic group (for example, a furyl group, a thienyl group, a pyridyl group, a pyridazinyl group, a pyrimidinyl group, a pyrazinyl group, Triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazin
  • aromatic hydrocarbon group and aromatic heterocyclic group may each have a substituent represented by R ′ and R ′′ in X of the general formula (1).
  • examples of the atoms represented by y 1 and y 2 include CR ′ and nitrogen atom, and CR ′ is more preferable.
  • Such a compound is excellent in hole transportability, and can efficiently recombine and emit holes and electrons injected from the anode and cathode in the light emitting layer.
  • examples of the aromatic ring represented by Ar 1 and Ar 2 include an aromatic hydrocarbon ring and an aromatic heterocyclic ring.
  • the aromatic ring may be a single ring or a condensed ring, and may be unsubstituted or may have a substituent represented by R ′ and R ′′ in X of the general formula (1).
  • examples of the aromatic hydrocarbon ring represented by Ar 1 and Ar 2 include a benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, Naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, Examples include a picene ring, a pyrene ring, a pyranthrene ring, and an anthraanthrene ring.
  • examples of the aromatic heterocycle represented by Ar 1 and Ar 2 include a furan ring, a dibenzofuran ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, and a pyridazine.
  • These rings may further have a substituent represented by R ′ and R ′′ in the general formula (1).
  • the aromatic ring represented by Ar 1 and Ar 2 is preferably a carbazole ring, carboline ring, dibenzofuran ring, or benzene ring, and more preferably used.
  • the aromatic rings represented by Ar 1 and Ar 2 are each preferably a condensed ring of three or more rings, and as an aromatic hydrocarbon condensed ring in which three or more rings are condensed.
  • aromatic heterocycle condensed with three or more rings include an acridine ring, a benzoquinoline ring, a carbazole ring, a carboline ring, a phenazine ring, a phenanthridine ring, a phenanthroline ring, a carboline ring, a cyclazine ring, Kindin ring, tepenidine ring, quinindrin ring, triphenodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, diazacarbazole ring (any one of the carbon atoms constituting the carboline ring is a nitrogen atom Phenanthroline ring, dibenzofuran ring, dibenzothiophene ring, naphthofuran ring, naphthothiophene ring, benzodifuran ring, benzod
  • n represents an integer of 0 to 4, preferably 0 to 2, and particularly 1 to 2 when X is an oxygen atom or a sulfur atom. It is preferable.
  • a host compound having both a dibenzofuran ring and a carbazole ring is particularly preferable.
  • the compound represented by the general formula (1) is preferably a compound represented by the following general formula (2). That is, a compound having a carbazole ring substituted at the 3-position with a phenyl group is preferable. This is because such a compound tends to be particularly excellent in carrier transportability and excellent in carrier injection into quantum dots.
  • Ar 3 to Ar 5 each represents an aromatic ring, and may be the same or different.
  • n1 represents an integer of 0 to 4
  • n2 represents an integer of 0 to 5.
  • Examples of the aromatic ring represented by Ar 3 to Ar 5 include the same aromatic rings as those represented by Ar 1 and Ar 2 in the general formula (1).
  • Light-Emitting Material As the light-emitting material applied to the light-emitting layer, generally, a fluorescent compound or a phosphorescent material (also referred to as a phosphorescent compound, a phosphorescent compound, or a phosphorescent dopant) is used. However, in the light emitting layer according to the present invention, at least a phosphorescent compound is used as the light emitting material.
  • the phosphorescent compound is a compound in which light emission from an excited triplet is observed, specifically a compound that emits phosphorescence at room temperature (25 ° C.), and has a phosphorescence quantum yield. Although defined as a compound of 0.01 or more at 25 ° C., a preferred phosphorescence quantum yield is 0.1 or more.
  • the phosphorescence quantum yield can be measured, for example, by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of the Fourth Edition Experimental Chemistry Course 7. Although the phosphorescence quantum yield in a solution can be measured using various solvents, in the phosphorescent light emitting material according to the present invention, the phosphorescence quantum yield (0.01 or more) is obtained in any solvent. It only has to be achieved.
  • the excited state energy of the phosphorescent material is lower than the excited state energy of the host compound.
  • the phosphorescent light-emitting material can be appropriately selected from known materials used for the light-emitting layer of the organic EL element, but is preferably a complex compound containing a group 8-10 metal in the periodic table of elements. More preferred are iridium compounds, osmium compounds, platinum compounds (platinum complex compounds), and rare earth complexes, and most preferred are iridium compounds.
  • the phosphorescent dopant according to the present invention in which the emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum is in the range of 496 to 827 nm (2.5 to 1.5 eV). It is preferable that White illumination with high color rendering can be obtained by combining the spectrum of the phosphorescent dopant having an emission wavelength in such a range and the quantum dot compound emitting light at 413 to 477 nm according to the present invention.
  • the emission wavelength attributed to the 0-0 transition band of the phosphorescent dopant according to the present invention can be determined by the same method used for the measurement of the emission wavelength attributed to the 0-0 transition band of the host compound. .
  • the phosphorescent compound according to the present invention is preferably a phosphorescent dopant represented by the following general formula (3).
  • R 1 represents a substituent.
  • Z represents a nonmetallic atom group necessary for forming a 5- to 7-membered ring.
  • n1 represents an integer of 0 to 5.
  • B 1 to B 5 each represent a carbon atom, a nitrogen atom, an oxygen atom, or a sulfur atom, and at least one represents a nitrogen atom.
  • M 1 represents a group 8 to group 10 metal in the periodic table.
  • X 1 and X 2 each represent a carbon atom, a nitrogen atom or an oxygen atom, and L 1 represents an atomic group which forms a bidentate ligand together with X 1 and X 2 .
  • m1 represents an integer of 1, 2, or 3
  • m2 represents an integer of 0, 1, or 2
  • m1 + m2 is 2 or 3.
  • the phosphorescent compound represented by the general formula (3) according to the present invention has a HOMO of ⁇ 5.15 to ⁇ 3.50 eV, a LUMO of ⁇ 1.25 to +1.00 eV, and preferably a HOMO of ⁇ 4.80 to ⁇ 3.50 eV, and LUMO is ⁇ 0.80 to +1.00 eV.
  • examples of the substituent represented by R 1 include an alkyl group (eg, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group).
  • Z represents a nonmetallic atom group necessary for forming a 5- to 7-membered ring.
  • the 5- to 7-membered ring formed by Z include a benzene ring, naphthalene ring, pyridine ring, pyrimidine ring, pyrrole ring, thiophene ring, pyrazole ring, imidazole ring, oxazole ring and thiazole ring. Of these, a benzene ring is preferred.
  • B 1 to B 5 each represent a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom, and at least one represents a nitrogen atom.
  • the aromatic nitrogen-containing heterocycle formed by these five atoms is preferably a monocycle. Examples include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, oxadiazole ring, and thiadiazole ring.
  • a pyrazole ring and an imidazole ring are preferable, and an imidazole ring in which B 2 and B 5 are each a nitrogen atom is particularly preferable.
  • These rings may be further substituted with the above substituents.
  • Preferred as the substituent are an alkyl group and an aryl group, and more preferably an aryl group.
  • L 1 represents an atomic group that forms a bidentate ligand together with X 1 and X 2 .
  • Specific examples of the bidentate ligand represented by X 1 -L 1 -X 2 include, for example, substituted or unsubstituted phenylpyridine, phenylpyrazole, phenylimidazole, phenyltriazole, phenyltetrazole, pyrazabol, picolinic acid And acetylacetone. These groups may be further substituted with the above substituents.
  • n1 represents an integer of 1, 2 or 3
  • m2 represents an integer of 0, 1 or 2
  • m1 + m2 is 2 or 3.
  • the case where m2 is 0 is preferable.
  • the metal represented by M 1 a transition metal element belonging to Group 8 to 10 of the periodic table (also simply referred to as a transition metal) is used, among which iridium and platinum are preferable, and iridium is more preferable.
  • phosphorescent dopants that can be used in the present invention are described.
  • these compounds among these compounds, they belong to the 0-0 transition band in the phosphorescence spectrum.
  • Patent documents such as Japanese Patent Laid-Open No. 2002-363552, and the like.
  • a preferable phosphorescent dopant includes an organometallic complex having Ir as a central metal. More preferably, a complex containing at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, and a metal-sulfur bond is preferable.
  • the present invention is characterized in that the light emitting layer according to the present invention contains quantum dots that emit light in a light emission wavelength range of 413 to 477 nm, that is, in a blue region. More preferably, it is in the range of 440 to 470 nm. More preferably, the quantum dot emits light within a range of 445 to 465 nm, particularly preferably within a range of 450 to 460 nm.
  • the quantum dots 11 may be contained in the light emitting layer 5, or the light emitting layer 5 and a layer adjacent to the light emitting layer 5 (for example, the hole transport layer 4 or the electron transport). It may be present at the interface with layer 6).
  • FIG. 2 shows an example in which quantum dots 11 are present at the interface between the light emitting layer 5 and the electron transport layer 6 adjacent to the light emitting layer 5.
  • a mode in which the quantum dots 11 are present at least in the light emitting layer 5 is preferable.
  • the quantum dot according to the present invention refers to a particle having a predetermined size that is composed of a crystal of a semiconductor material and has a quantum confinement effect, and is a fine particle having a particle diameter of several nanometers to several tens of nanometers. The quantum dot effect shown is obtained.
  • the particle diameter of the quantum dots (fine particles) according to the present invention is specifically preferably in the range of 1 to 20 nm, more preferably in the range of 1 to 10 nm.
  • the energy level E of such a quantum dot is generally expressed by the following formula (I) when the Planck constant is “h”, the effective mass of the electron is “m”, and the radius of the fine particle is “R”. Is done.
  • the band gap of the quantum dot increases in proportion to “R ⁇ 2 ”, and a so-called quantum dot effect is obtained.
  • the band gap value of a quantum dot can be controlled by controlling and defining the particle diameter of the quantum dot. That is, by controlling and defining the particle diameter of the fine particles, it is possible to provide diversity not found in ordinary atoms. For this reason, electrical energy can be converted into light of the desired wavelength by exciting electrons with light or applying voltage to organic EL elements that contain quantum dots to confine electrons and holes in the quantum dots and recombine them. Can be emitted.
  • such a luminescent quantum dot material is defined as a quantum dot according to the present invention.
  • the average particle diameter of the quantum dots is about 1 nm to several tens of nm as described above, but when used as one of white light emitting materials, it is set to an average particle diameter corresponding to the target luminescent color.
  • the average particle diameter of the quantum dots is preferably set within a range of 3.0 to 20 nm.
  • the average particle diameter of the quantum dots is set to It is preferable to set within the range of 1.5 to 10 nm, and when it is desired to obtain blue light emission, it is preferable to set the average particle diameter of the quantum dots within the range of 1.0 to 3.0 nm.
  • the particle size to be produced is not the above particle size.
  • the total particle size including these is preferably in the range of 1 to 20 nm. More preferably, the particle diameter is in the range of 5 to 17 nm, and more preferably 10 to 15 nm.
  • a known method can be used as a method for measuring the average particle diameter of the quantum dots.
  • a quantum dot particle observation is performed with a transmission electron microscope (TEM), and a method for obtaining the number average particle size of the particle size distribution therefrom, or a method for obtaining an average particle size using an electron force microscope (AFM),
  • a particle size measuring apparatus using a dynamic light scattering method for example, “ZETASIZER Nanos Nano-ZS, manufactured by Malvern, Inc. can also be measured.
  • quantum dots can be obtained from spectra obtained by the X-ray small angle scattering method.
  • a method of deriving a particle size distribution using particle size distribution simulation calculation and the like can be mentioned.
  • a method of obtaining an average particle size using an electron force microscope (AFM) is preferable.
  • the aspect ratio (major axis diameter / minor axis diameter) is preferably in the range of 1.0 to 2.0, more preferably 1.1 to 1. Within the range of .7.
  • the aspect ratio (major axis diameter / minor axis diameter) related to the quantum dots according to the present invention can also be determined by measuring the major axis diameter and the minor axis diameter using, for example, an electron force microscope (AFM). .
  • the number of individuals to be measured is preferably 300 or more.
  • the addition amount of the quantum dots is preferably in the range of 0.01 to 50% by mass, and in the range of 0.05 to 25% by mass, when the total constituent materials of the layer to be added are 100% by mass. More preferably, it is most preferably in the range of 0.1 to 20% by mass. If the addition amount is 0.01% by mass or more, white light emission with sufficient luminance efficiency and good color rendering can be obtained, and if it is 50% by mass or less, an appropriate distance between quantum dot particles can be maintained. The size effect can be exhibited sufficiently.
  • the above-described phosphorescent compound has a relatively long excitation lifetime of the order of milliseconds or microseconds, when the concentration in the layer is too high, the exciton energy relaxes and disappears. The problem of concentration quenching occurs.
  • the quantum dots according to the present invention to exist at the interface with the light emitting layer or its adjacent layer, not only the light emission of the quantum dots and the phosphorescent compound itself can be obtained, but the details are unknown but the quantum dots
  • the effect of improving the luminous efficiency of the phosphorescent compound which is presumed to be due to the change in the shape of the entire layer and the improved dispersibility of the phosphorescent compound due to the surface energy of the quantum dots, can be obtained.
  • Examples of the constituent material of the quantum dot include a simple substance of a periodic table group 14 element such as carbon, silicon, germanium, and tin, a simple substance of a periodic table group 15 element such as phosphorus (black phosphorus), and a periodicity of selenium, tellurium, and the like.
  • Table 16 group element simple substance, compound consisting of a plurality of periodic table group 14 elements such as silicon carbide (SiC), tin oxide (IV) (SnO 2 ), tin sulfide (II, IV) (Sn (II) Sn (IV) S 3 ), tin sulfide (IV) (SnS 2 ), tin (II) sulfide (SnS), tin (II) selenide (SnSe), tin telluride (II) (SnTe), lead sulfide (II) ) (PbS), lead selenide (II) (PbSe), lead telluride (II) (PbTe) periodic table group 14 element and periodic table group 16 element compound, boron nitride (BN), phosphorus Boron halide (BP), Boron arsenide (BAs), Aluminum nitride (AlN), Al phosphide Ni (AlP
  • III-V group compound semiconductors aluminum sulfide ( Al 2 S 3 ), aluminum selenide (Al 2 Se 3 ), gallium sulfide (Ga 2 S 3 ), gallium selenide (Ga 2 Se 3 ), gallium telluride (Ga 2 Te 3 ), indium oxide (In 2) O 3), indium sulfide (In 2 S 3), indium selenide (I 2 Se 3), compounds of tellurium indium (In 2 Te 3) periodic table group 13 elements and the periodic table group 16 element such as, thallium chloride (I) (TlCl), thallium bromide (I) (TlBr ), Compounds of group 13 elements of the periodic table and elements of group 17 of the periodic table such as thallium (I) iodide (TlI), zinc oxide (ZnO), zinc sulfide (ZnS), zinc selenide (ZnSe), tellurium Zinc iodide (ZnTe), cadmi
  • Group 15 elements and Group 16 elements of the periodic table, Group 11 elements of the periodic table and Group 16 of the periodic table such as copper (I) (Cu 2 O), copper selenide (Cu 2 Se), etc.
  • Periodic tables of compounds with elements copper chloride (I) (CuCl), copper bromide (I) (CuBr), copper iodide (I) (CuI), silver chloride (AgCl), silver bromide (AgBr), etc.
  • Nickel oxide (II) N compounds of periodic table group 10 elements such as iO) and periodic table group 16 elements
  • periodic table group 9 elements such as cobalt (II) oxide (CoO), cobalt sulfide (II) (CoS) and periodic table Compounds with Group 16 elements
  • compounds of Group 8 elements of the periodic table such as triiron tetroxide (Fe 3 O 4 ), iron (II) sulfide (FeS), and Group 16 elements of the periodic table
  • manganese (II) oxide A compound of a periodic table group 7 element such as (MnO) and a periodic table group 16 element, a periodic table group 6 element such as molybdenum sulfide (IV) (MoS 2 ), tungsten oxide (IV) (WO 2 ), etc.
  • Periodic Table Group 5 elements such as vanadium (II) oxide (VO), vanadium oxide (IV) (VO 2 ), tantalum oxide (V) (Ta 2 O 5 ) and the period Table compound of group 16 element, a titanium oxide (TiO 2, Ti 2 O 5 , Ti 2 O , A compound of Group 4 of the periodic table element and Periodic Table Group 16 element of Ti 5 O 9, etc.) and the like, magnesium sulfide (MgS), the second group elements and the periodic table periodic table such as magnesium selenide (MgSe) Compounds with group 16 elements, cadmium (II) chromium (III) (CdCr 2 O 4 ), cadmium selenide (II) chromium (III) (CdCr 2 Se 4 ), copper sulfide (II) chromium (III) ( Examples thereof include chalcogen spinels such as CuCr 2 S 4 ), mercury (II) se
  • III-V group compound semiconductors such as Ga 2 O 3 , Ga 2 S 3 , Ga 2 Se 3 , Ga 2 Te 3 , In 2 O 3 , In 2 S 3 , In 2 Se 3 , In 2 Te 3, etc.
  • Compounds of Group 13 elements and Group 16 elements of the periodic table ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgO, HgS, HgSe, HgTe and other II-VI group compound semiconductors, As 2 O 3 , As 2 S 3 , As 2 Se 3 , As 2 Te 3 , Sb 2 O 3 , Sb 2 S 3 , Sb 2 Se 3 , Sb 2 Te 3 , Bi 2 O 3 , Bi 2 S 3 , Bi 2
  • a compound of a periodic table group 15 element such as Se 3 or Bi 2 Te 3 and a group 16 element of the periodic table, a compound of periodic table group 2 element such as MgS or MgSe, and a group 16 element of the periodic table are preferable, Among them, Si, Ge GaN, GaP, InN, InP, Ga 2 O 3 , Ga 2 S 3 , In 2 O 3 , In 2 S 3 , Z
  • CdSe, ZnSe, and CdS are preferable in terms of light emission stability.
  • ZnO and ZnS quantum dots are preferable.
  • said material may be used by 1 type and may be used in combination of 2 or more type.
  • quantum dots can be doped with a small amount of various elements as impurities as necessary. By adding such a doping substance, the emission characteristics can be greatly improved.
  • the quantum dot according to the present invention is characterized in that the emission wavelength is in the range of 413 to 477 nm (2.6 to 3.6 eV).
  • the band gap (eV) of a quantum dot can be measured using a Tauc plot.
  • the Tauc plot which is one of the optical scientific measurement methods of the band gap (eV), will be described.
  • quantum dots were generated not only in light emission due to direct recombination of holes and electrons in the quantum dots, but also in an organic electron block hole transport layer, an organic light emission layer, or a hole block electron transport layer.
  • the energy of excitons may be absorbed by the quantum dots to obtain light emission from the quantum dot core. Since these quantum dots are lightly doped, other phosphorescent compounds can also absorb the exciton energy to obtain light emission.
  • the surface of the quantum dot is preferably coated with an inert inorganic coating layer or a coating composed of an organic ligand. That is, the surface of the quantum dot has a core / shell structure having a core region made of a quantum dot material and a shell region made of an inert inorganic coating layer or an organic ligand. Is preferred.
  • This core / shell structure is preferably formed of at least two kinds of compounds, and a gradient structure (gradient structure) may be formed of two or more kinds of compounds.
  • a gradient structure gradient structure
  • a surface modifier as described later can be reliably supported in the vicinity of the surface of the quantum dot.
  • the thickness of the coating (shell part) is not particularly limited, but is preferably in the range of 0.1 to 10 nm, and more preferably in the range of 0.1 to 5 nm.
  • the emission color can be controlled by controlling the average particle diameter of the quantum dots. If the thickness of the coating is a value within the above range, the thickness of the coating corresponds to the number of atoms. Thus, the thickness is less than one quantum dot, the quantum dots can be filled with high density, and a sufficient amount of light emission can be obtained. In addition, the presence of the coating can suppress non-luminous electron energy transfer due to defects existing on the particle surfaces of the core particles and electron traps on the dangling bonds, thereby suppressing a decrease in quantum efficiency.
  • Functional surface modifiers applicable in the present invention may be those directly attached to the surface of the quantum dots, or those attached via a shell (the surface modifier is directly attached to the shell. In other words, it may not be in contact with the core of the quantum dot.
  • the surface modifier examples include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; tripropylphosphine, tributylphosphine, trihexylphosphine, trioctylphosphine, and the like.
  • Trialkylphosphines polyoxyethylene alkylphenyl ethers such as polyoxyethylene n-octylphenyl ether and polyoxyethylene n-nonylphenyl ether; tri (n-hexyl) amine, tri (n-octyl) amine, tri ( tertiary amines such as n-decyl) amine; tripropylphosphine oxide, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphineoxy Organic phosphorus compounds such as tridecylphosphine oxide; polyethylene glycol diesters such as polyethylene glycol dilaurate and polyethylene glycol distearate; organic nitrogen compounds such as nitrogen-containing aromatic compounds such as pyridine, lutidine, collidine and quinolines; hexylamine; Aminoalkanes such as octylamine, decylamine, dodecyl
  • the surface modifier may be a fine particle of quantum dots in a high-temperature liquid phase. It is preferable that the substance is coordinated to be stabilized, specifically, trialkylphosphines, organic phosphorus compounds, aminoalkanes, tertiary amines, organic nitrogen compounds, dialkyl sulfides, dialkyl sulfoxides. , Organic sulfur compounds, higher fatty acids and alcohols are preferred.
  • the dispersibility of the quantum dots in the coating solution can be made particularly excellent.
  • the shape of the quantum dot formed at the time of manufacture of a quantum dot can be made into a higher sphericity, and the particle size distribution of a quantum dot can be made sharper.
  • the size (average particle diameter) of the quantum dots is preferably in the range of 1 to 20 nm.
  • the size of the quantum dots means the total area composed of a core region composed of a quantum dot material, a shell region composed of an inert inorganic coating layer or an organic ligand, and a surface modifier. Represents size. If the surface modifier or shell is not included, the size does not include it.
  • an aqueous raw material is used, for example, alkanes such as n-heptane, n-octane, isooctane, or benzene, toluene.
  • Inverted micelles which exist as reverse micelles in non-polar organic solvents such as aromatic hydrocarbons such as xylene, and crystal growth in this reverse micelle phase, inject a thermally decomposable raw material into a high-temperature liquid-phase organic medium
  • examples thereof include a hot soap method for crystal growth and a solution reaction method involving crystal growth at a relatively low temperature using an acid-base reaction as a driving force, as in the hot soap method. Any method can be used from these production methods, and among these, the liquid phase production method is preferred.
  • the organic surface modifier present on the surface when the quantum dots are synthesized is referred to as an initial surface modifier.
  • the initial surface modifier in the hot soap method include trialkylphosphines, trialkylphosphine oxides, alkylamines, dialkyl sulfoxides, alkanephosphonic acid and the like. These initial surface modifiers are preferably exchanged for the above-described functional surface modifiers by an exchange reaction.
  • the initial surface modifier such as trioctylphosphine oxide obtained by the hot soap method is the above-described functional surface modifier by an exchange reaction performed in a liquid phase containing the functional surface modifier. It is possible to exchange with.
  • the following shows an example of a method for producing quantum dots.
  • n-octanethiol added to TOA (210 ⁇ l in 6 ml) is injected into the above solution at a rate of 1 ml / min using a syringe pump and allowed to react for 40 minutes. This is referred to as a Cd-containing reaction medium.
  • a 16 ml aliquot of Zn-oleic acid solution (the Zn precursor solution heated at 100 ° C.) is injected into the Cd-containing reaction medium at a rate of 2 ml / min.
  • 6.4 mmol of n-octanethiol in TOA (1.12 ml in 6 ml) is injected at a rate of 1 ml / min using a syringe pump.
  • the quantum dot film formation method is preferably a wet process.
  • spin coating method casting method, die coating method, blade coating method, roller coating method, ink jet method, printing method, spray coating method, curtain coating method, LB method (Langmuir Brodgett method), etc.
  • LB method Liangmuir Brodgett method
  • a film forming method using a transfer method in which a quantum dot monomolecular film is formed on another medium and then transferred is also useful.
  • the solvent to be used preferably includes a solvent having a boiling point in the range of 100 to 150 ° C.
  • a solvent having such a boiling range an appropriate drying speed is obtained, the quantum dot compound contained in the coating film can be properly oriented, and higher luminous efficiency and durability can be obtained.
  • a solvent such as toluene, xylene, chlorobenzene, n-butanol and the like can be raised.
  • a mixed solvent containing these solvents may be used, and the ratio is preferably in the range of 9: 1 to 0:10.
  • an electrode using a metal, an alloy, an electrically conductive compound and a mixture thereof having a high work function (4 eV or more) as an electrode material is preferably used.
  • an electrode substance include a conductive transparent material such as a metal such as Au, CuI, indium-tin composite oxide (hereinafter abbreviated as ITO), SnO 2 , and ZnO.
  • a conductive transparent material such as a metal such as Au, CuI, indium-tin composite oxide (hereinafter abbreviated as ITO), SnO 2 , and ZnO.
  • an amorphous material such as IDIXO (In 2 O 3 —ZnO) capable of forming a transparent conductive film may be used.
  • these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a desired shape pattern may be formed by a photolithography method, or when pattern accuracy is not so high (about 100 ⁇ m or more)
  • a pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material.
  • wet film-forming methods such as a printing system and a coating system, can also be used.
  • the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred ⁇ / ⁇ or less.
  • the film thickness is usually in the range of 10 to 1000 nm, preferably in the range of 10 to 200 nm.
  • cathode On the other hand, as the cathode constituting the organic EL device of the present invention, a cathode having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound and a mixture thereof as an electrode material. Used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al 2 O 3 ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like.
  • a mixture of an electron injectable metal that is the first metal and a second metal that is a stable metal having a larger work function than this for example, Suitable are a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al 2 O 3 ) mixture, a lithium / aluminum mixture, aluminum and the like.
  • the cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
  • the sheet resistance as the cathode is preferably several hundred ⁇ / ⁇ or less, and the film thickness is usually in the range of 10 nm to 5 ⁇ m, preferably in the range of 50 to 200 nm.
  • the light emission luminance is improved and it is convenient.
  • a transparent or translucent cathode can be produced.
  • an organic EL element in which both the anode and the cathode are transmissive can be produced.
  • the support substrate (hereinafter also referred to as a substrate, substrate, base material, support, etc.) that can be used in the organic EL device of the present invention is not particularly limited, such as glass, plastic, etc., and is transparent. It may be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A substrate that is more flexible than a rigid substrate is preferable from the viewpoint that the effect of suppressing high-temperature storage stability and chromaticity fluctuation is greatly exhibited, and a particularly preferable support substrate is a flexible substrate that can give flexibility to an organic EL element. It is preferable that it is the resin film provided with property.
  • polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, and cellulose acetate propionate ( CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (
  • the surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and the water vapor permeability (25 ⁇ 0.5 ° C.) measured by a method according to JIS K 7129-1992.
  • Relative humidity (90 ⁇ 2)% RH) is preferably 0.01 g / (m 2 ⁇ 24 h ⁇ atm) or less, and further measured by a method according to JIS K 7126-1987.
  • the water vapor permeability is more preferably 1 ⁇ 10 ⁇ 5 g / (m 2 ⁇ 24 h ⁇ atm) or less.
  • the material for forming the gas barrier layer may be any material that has a function of suppressing the intrusion of factors that cause deterioration of the organic EL element such as moisture and oxygen.
  • silicon oxide, silicon dioxide, silicon nitride, or the like is used. be able to.
  • the method for forming the gas barrier layer is not particularly limited.
  • a plasma polymerization method, a plasma CVD method (CVD: Chemical Vapor Deposition), a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma as described in JP-A-2004-68143.
  • a polymerization method is particularly preferred.
  • the opaque support substrate examples include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.
  • the external extraction efficiency of light emission at room temperature is preferably 1% or more, more preferably 5% or more.
  • the external extraction quantum efficiency (%) the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element ⁇ 100.
  • a sealing means applicable to the organic EL element of the present invention for example, a method of adhering a sealing member, an electrode, and a support substrate with a sealing adhesive can be mentioned.
  • the sealing member may be disposed so as to cover the display area of the organic EL element, and may be a concave plate shape or a flat plate shape. Further, transparency and electrical insulation are not particularly limited.
  • Specific examples include a glass plate, a polymer plate / film composite material, and a metal plate / film composite material.
  • the glass plate include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.
  • the material constituting the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone.
  • Examples of the material constituting the metal plate include one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicone, germanium, and tantalum.
  • the sealing member a polymer film and a metal film can be preferably used because the organic EL element can be thinned.
  • the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 ⁇ 10 ⁇ 3 cm 3 / (m 2 ⁇ 24 h ⁇ atm) or less, and conforms to JIS K 7129-1992.
  • the water vapor permeability (25 ⁇ 0.5 ° C., relative humidity (90 ⁇ 2)% RH) measured by the above method is preferably 1 ⁇ 10 ⁇ 3 g / (m 2 ⁇ 24 h) or less.
  • sealing member For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.
  • the sealing adhesive include photo-curing and thermosetting adhesives having a reactive vinyl group of acrylic acid-based oligomers and methacrylic acid-based oligomers, and moisture-curing types such as 2-cyanoacrylic acid esters. Mention may be made of adhesives. Moreover, heat
  • an organic EL element may deteriorate by heat processing, what can be adhesive-hardened within the temperature range from room temperature to 80 degreeC is preferable. Further, a desiccant may be dispersed in the adhesive. Application
  • coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.
  • the material for forming the film may be a material having a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen.
  • silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.
  • vacuum deposition method sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma
  • a polymerization method a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.
  • an inert gas such as nitrogen or argon, an inert gas such as fluorinated hydrocarbon or silicon oil is used. It is preferable to inject a liquid. A vacuum is also possible. Moreover, a hygroscopic compound can also be enclosed inside.
  • hygroscopic compound examples include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate).
  • metal oxides for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide
  • sulfates for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate.
  • metal halides eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.
  • perchloric acids eg perchloric acid Barium, magnesium perchlorate, and the like
  • anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.
  • Sealing includes casing type sealing (can sealing) and close contact type sealing (solid sealing), but solid sealing is preferable from the viewpoint of thinning. Moreover, when producing a flexible organic EL element, since sealing is also required for the sealing member, solid sealing is preferable.
  • thermosetting adhesive an ultraviolet curable resin, or the like
  • a thermosetting adhesive such as an epoxy resin, an acrylic resin, or a silicone resin, more preferably moisture resistant. It is an epoxy thermosetting adhesive resin that is excellent in water resistance and water resistance and has little shrinkage during curing.
  • the water content of the sealing adhesive according to the present invention is preferably 300 ppm or less, more preferably 0.01 to 200 ppm, and most preferably 0.01 to 100 ppm.
  • the moisture content in the present invention may be measured by any method.
  • a volumetric moisture meter Karl Fischer
  • an infrared moisture meter a microwave transmission moisture meter
  • a heat-dry weight method a GC / MS
  • IR a GC / MS
  • IR a GC / MS
  • IR a GC / MS
  • IR a GC / MS
  • IR a GC / MS
  • IR IR
  • DSC Densonic Scanning Calorimeter
  • TDS Temporal Scanning Calorimeter
  • the moisture content of the sealing adhesive can be adjusted by, for example, placing it in a nitrogen atmosphere with a dew point temperature of ⁇ 80 ° C. or lower and an oxygen concentration of 0.8 ppm, and changing the time. Further, it can be dried in a vacuum state of 100 Pa or less while changing the time. Further, the sealing adhesive can be dried only with an adhesive, but can also be placed in advance on the sealing member and dried.
  • the sealing member for example, a 50 ⁇ m thick PET (polyethylene terephthalate) film laminated with an aluminum foil (30 ⁇ m thick) can be used.
  • a sealing adhesive was placed in advance, the resin substrate and the sealing member were aligned, and both were crimped (0 0.1-3 MPa) and at a temperature of 80-180 ° C., it can be tightly bonded (bonded) to achieve close sealing (solid sealing).
  • the heating or pressure bonding time varies depending on the type, amount, and area of the adhesive, but temporary bonding is performed at a pressure within the range of 0.1 to 3 MPa, and the thermosetting time is at a temperature within the range of 80 to 180 ° C. You can select from 5 seconds to 10 minutes.
  • a coating method such as roller coating, spin coating, screen printing, spray coating, or the like can be used using a dispenser.
  • solid sealing is a form in which there is no space between the sealing member and the organic EL element substrate and the resin is covered with a cured resin.
  • sealing member examples include metals such as stainless steel, aluminum, and magnesium alloys, polyethylene terephthalate, polycarbonate, polystyrene, nylon, plastics such as polyvinyl chloride, and composites thereof, glass, and the like.
  • metals such as stainless steel, aluminum, and magnesium alloys
  • polyethylene terephthalate polycarbonate
  • polystyrene polystyrene
  • nylon plastics
  • plastics such as polyvinyl chloride, and composites thereof, glass, and the like.
  • gas barrier layers such as aluminum, aluminum oxide, silicon oxide, and silicon nitride can be used in the same manner as the resin substrate.
  • the gas barrier layer can be formed by sputtering, vapor deposition or the like on both surfaces or one surface of the sealing member before molding the sealing member, or can be formed on both surfaces or one surface of the sealing member by the same method after sealing. Good.
  • the oxygen permeability is 1 ⁇ 10 ⁇ 3 ml / (m 2 ⁇ 24 h ⁇ atm) or less
  • the water vapor permeability (25 ⁇ 0.5 ° C., relative humidity (90 ⁇ 2)% RH) is 1 ⁇ It is preferably 10 ⁇ 3 g / (m 2 ⁇ 24 h) or less.
  • the sealing member may be a film laminated with a metal foil such as aluminum.
  • a method for laminating the polymer film on one side of the metal foil a generally used laminating machine can be used.
  • the adhesive polyurethane-based, polyester-based, epoxy-based, acrylic-based adhesives and the like can be used. You may use a hardening
  • a hot melt lamination method, an extrusion lamination method and a coextrusion lamination method can also be used, but a dry lamination method is preferred.
  • the metal foil when the metal foil is formed by sputtering or vapor deposition and is formed from a fluid electrode material such as a conductive paste, it may be created by a method of forming a metal foil on a polymer film as a base. Good.
  • a protective film or a protective plate may be provided outside the sealing film on the side facing the support substrate with the organic functional layer interposed therebetween or on the outer side of the sealing film.
  • the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate.
  • the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used, but the polymer film is light and thin. Is preferably used.
  • a light extraction member between the flexible support substrate and the anode or at any location on the light emission side from the flexible support substrate.
  • Examples of the light extraction member include a prism sheet, a lens sheet, and a diffusion sheet. Further, a diffraction grating or a diffusion structure introduced into an interface or any medium that causes total reflection can be used.
  • an organic electroluminescence element that emits light from a substrate
  • a part of the light emitted from the light emitting layer causes total reflection at the interface between the substrate and air, causing a problem of loss of light.
  • prismatic or lens-like processing is applied to the surface of the substrate, or prism sheets, lens sheets, and diffusion sheets are attached to the surface of the substrate, thereby suppressing total reflection and light extraction efficiency. To improve.
  • a desired electrode material for example, a thin film made of an anode material is formed on a suitable substrate by a thin film forming method such as vapor deposition or sputtering so as to have a thickness of 1 ⁇ m or less, preferably 10 to 200 nm.
  • An anode is produced.
  • an organic functional layer (organic compound thin film) of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer, which are organic EL element materials, is formed thereon.
  • the process of forming the organic functional layer mainly includes (I) a coating step in which the coating liquid prepared by preparing each material constituting the organic functional layer is coated and laminated on the anode of the support substrate; (Ii) a drying step of drying the coating film formed by applying and laminating; Consists of.
  • a wet process for example, spin coating method, casting method, die coating method, blade coating method, roller coating method, ink jet method, printing method, spray coating method, curtain
  • a light emitting layer containing at least quantum dots can be used such as a coating method and an LB method (Langmuir Brodgett method can be used).
  • the light emitting layer forming coating solution contains a solvent having a boiling point in the range of 100 to 150 ° C.
  • a wet process in the present invention from the viewpoint that a homogeneous film is easily obtained and pinholes are difficult to be generated, among others, a spin coating method, a casting method, Film formation by a coating method such as a die coating method, a blade coating method, a roller coating method, or an ink jet method is preferable.
  • Examples of the organic solvent used for dissolving or dispersing the organic EL material according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, Aromatic hydrocarbons such as xylene, mesitylene, and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) can be used.
  • ketones such as methyl ethyl ketone and cyclohexanone
  • fatty acid esters such as ethyl acetate
  • halogenated hydrocarbons such as dichlorobenzene, toluene
  • Aromatic hydrocarbons such as xylene, mesitylene
  • a solvent having a boiling point in the range of 100 to 150 ° C it is preferable to use a solvent having a boiling point in the range of 100 to 150 ° C.
  • a dispersion method such as ultrasonic wave, high shear force dispersion or media dispersion can be appropriately selected and applied.
  • distributes the organic EL material which concerns on this invention, and the coating process until it applies a coating liquid on a base material are in inert gas atmosphere.
  • inert gas atmosphere since it is possible to form a film without degrading the performance of the organic EL element even if it is not carried out in an inert gas atmosphere depending on the material used, there are cases where not all the steps are necessarily carried out in an inert gas atmosphere. By taking such a measure, the manufacturing cost can be suppressed, which is more preferable.
  • drying means that the content is reduced to 0.2% by mass or less when the solvent content of the coating film immediately after coating is 100% by mass.
  • drying means those commonly used as general drying means can be used, and examples thereof include reduced pressure or pressure drying, heat drying, air drying, IR drying, and electromagnetic wave drying.
  • heat drying is preferable, and among the solvents used in the preparation of the organic functional layer coating solution, the temperature is equal to or higher than the boiling point of the lowest boiling solvent, and the lowest Tg among the glass transition temperatures Tg of the organic functional layer material. It is most preferable to hold at a temperature lower than (Tg + 20) ° C. of the material.
  • drying is preferably carried out while maintaining a temperature range of 80 to 150 ° C., more preferably drying while maintaining a temperature range of 100 to 130 ° C.
  • the atmosphere when drying the coating film after application and lamination is preferably an atmosphere in which the volume concentration of gas other than the inert gas is 200 ppm or less, but it is not necessarily inert as in the preparation step and the application step. There is a case where it is not necessary to carry out in a gas atmosphere. In this case, the manufacturing cost can be suppressed, which is more preferable.
  • the inert gas is preferably a rare gas such as nitrogen gas or argon gas, and most preferably nitrogen gas in terms of production cost.
  • the coating, laminating and drying steps of these organic functional layers may be a single wafer manufacturing method or a continuous online manufacturing method. Furthermore, the drying step may be performed during conveyance on the conveyance line, but from the viewpoint of productivity, it may be wound up and dried in a non-contact manner in the form of a deposit or a roll.
  • a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 ⁇ m or less, preferably in the range of 50 to 200 nm.
  • the organic EL element can be produced by adhering the contact sealing or sealing member to the electrode and the support substrate with an adhesive.
  • the organic EL element of the present invention can be used as a display device, a display, and various light emission sources.
  • Examples of light sources include home lighting, interior lighting, backlights for watches and liquid crystals, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, and light sources for optical sensors. Furthermore, it can be used in a wide range of applications such as general household appliances that require a display device, but it can be used effectively as a backlight of a liquid crystal display device combined with a color filter, and as a light source for illumination. it can.
  • patterning may be performed by a metal mask, an ink jet printing method, or the like during film formation, if necessary.
  • patterning only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned.
  • a conventionally known method is used. Can do.
  • Organic EL elements 1 to 15 were produced according to the following method.
  • the gas barrier layer is formed to have a thickness of 500 nm, the oxygen permeability is 0.001 ml / (m 2 ⁇ day ⁇ atm) or less, and the water vapor permeability is 0.001 g / (m 2 ⁇ day ⁇ atm) or less.
  • a gas barrier flexible film was prepared.
  • ITO indium-tin composite oxide
  • An ITO (indium-tin composite oxide) film having a thickness of 120 nm is formed by sputtering on the gas barrier flexible film produced above, and photolithography is performed. Patterning was performed by the method to form a first electrode layer (anode). The pattern was such that the light emission area was 50 mm square.
  • a light emitting layer composition 1 having the following composition was formed by spin coating at 1500 rpm for 30 seconds, dried at 120 ° C. for 30 minutes, and dried to a thickness of 40 nm. A light emitting layer was formed.
  • ⁇ Light emitting layer composition 1> Host compound: Exemplified compound H-55 (emission wavelength: 420 nm, 2.95 eV, molecular weight: 651, described in Chemical formula 14) 13.95 parts by mass Green dopant DG (emission wavelength: 520 nm) 0.25 parts by mass Red dopant DR ( (Emission wavelength: 620 nm) 0.10 parts by mass Quantum dot 1 Core part: CdSe (2 nm) / shell part ZnS (octadecylamine), average particle diameter 7 nm, aspect ratio 1.25, emission wavelength: 459 nm, 2.7 eV) 3.0 parts by mass Toluene 2,000 parts by mass
  • the following electron transport material B can be synthesized with reference to Japanese Patent Application Laid-Open No. 2010-235575.
  • a flexible aluminum foil manufactured by Toyo Aluminum Co., Ltd.
  • a polyethylene terephthalate (PET) film (12 ⁇ m thick)
  • an adhesive for dry lamination two-component reactive type
  • a laminate (a thickness of the adhesive layer of 1.5 ⁇ m) using a urethane adhesive) was used.
  • thermosetting adhesive as a sealing adhesive was uniformly applied at a thickness of 20 ⁇ m along the adhesive surface (glossy surface) of the aluminum foil using a dispenser. This was dried under a vacuum of 100 Pa or less for 12 hours. Furthermore, it moved to a nitrogen atmosphere with a dew point temperature of ⁇ 80 ° C. or lower and an oxygen concentration of 0.8 ppm, dried for 12 hours or longer, and adjusted the water content of the sealing adhesive to 100 ppm or lower.
  • thermosetting adhesive an epoxy adhesive mixed with the following (A) to (C) was used.
  • the organic EL device 1 of the present invention containing quantum dots in the light-emitting layer was produced by tightly sealing with a roller using a pressure roller temperature of 120 ° C., a pressure of 0.5 MPa, and an apparatus speed of 0.3 m / min. .
  • organic EL devices 2 to 13 were produced in the same manner except that Exemplified Compound H-55 was changed to each host compound shown in Table 1 as the host compound used in the light emitting layer. did.
  • a relative light emission luminance was determined with the light emission luminance of the organic EL element 14 as a comparative example being 1.0, and this was used as a measure of the light emission efficiency (external extraction quantum efficiency). It represents that it is excellent in luminous efficiency, so that a numerical value is large.
  • the drive voltage difference was determined based on the drive voltage of the organic EL element 14 as a comparative example.
  • the drive start and LT 50 reaches when the chromaticity (CIE color system x, y) and measured by the spectroradiometer, the start of driving the chromaticity (x, y) for the LT 50 at arrival
  • CIE color system x, y chromaticity
  • ⁇ x and ⁇ y color difference of chromaticity (x, y) was determined and used as a measure of color misregistration resistance. The smaller the numerical value, the smaller the color shift and the better the chromaticity stability.
  • the cantilever is a silicon cantilever SI-DF20 manufactured by Seiko Instruments Inc., which has a resonance frequency of 120 to 150 kHz and a spring constant of 12 to 20 N / m, and is measured in a DFM mode (Dynamic Force Mode). A measurement area of 80 ⁇ 80 ⁇ m was measured at a scanning frequency of 0.1 Hz.
  • the diameter of the quantum dot including the size of the ZnS shell is in the range of 5 to 15 nm in any sample, and the aspect ratio (ratio of the minor axis to the major axis of the quantum dot) is 1: 1 to 1: It was within the range of 1.5.
  • Table 1 shows the results obtained as described above.
  • the organic EL elements 1 to 12 of the present invention having the configuration defined in the present invention have higher emission luminance (emission efficiency) and lower drive voltage than the comparative example. Furthermore, it can be seen that the color rendering properties and the element lifetime are improved, and the chromaticity is stable.
  • the organic electroluminescence element of the present invention has high luminous efficiency, long life, and white light emission characteristics that are stable in chromaticity even with color rendering and low driving voltage, and can be suitably used as a display device, a display, and various light sources. .

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Abstract

The present invention addresses the problem of providing an organic electroluminescence element having a high light-emission efficiency and a long life, and a production method therefor, and in particular, providing a white light-emitting organic electroluminescence element having excellent color rendering properties and stable chromaticity even during low drive voltage, and a production method therefor. This organic electroluminescence element has at least a positive electrode, a hole transport layer, a light-emitting layer containing a phosphorescent light-emitting compound, an electron transport layer, and a negative electrode, and is characterized by the light-emitting layer containing: a quantum dot having light-emission wavelength within the range of 413-477 nm; and a host compound having a light-emission wavelength, belonging to a 0-0 transition band in a phosphorescence spectrum, within the range of 413-459 nm.

Description

有機エレクトロルミネッセンス素子及び有機エレクトロルミネッセンス素子の製造方法ORGANIC ELECTROLUMINESCENT ELEMENT AND METHOD FOR PRODUCING ORGANIC ELECTROLUMINESCENT ELEMENT
　本発明は、有機エレクトロルミネッセンス素子及びその製造方法に関し、詳しくは、発光効率、発光寿命及び演色性が改良された有機エレクトロルミネッセンス素子及びその製造方法に関する。 The present invention relates to an organic electroluminescence device and a method for producing the same, and more particularly to an organic electroluminescence device having improved light emission efficiency, light emission lifetime and color rendering properties and a method for producing the same.
　近年、有機材料を使用した有機エレクトロルミネッセンス素子（以下、有機ＥＬ素子ともいう。）は、固体発光型の軽量、薄型及び安価な大面積フルカラー表示素子や書き込み光源アレイとしての用途が有望視されており、研究開発が活発に進められている。 In recent years, organic electroluminescence elements using organic materials (hereinafter also referred to as organic EL elements) are promising for use as solid light-emitting, lightweight, thin, and inexpensive large-area full-color display elements and writing light source arrays. Research and development is actively underway.
　有機ＥＬ素子は、フィルム上に形成された一対の陽極と陰極との間に、有機発光物質を含有する厚さ僅か０．１μｍ程度の有機機能層を単層構成又は多層構成で有する薄膜型の全固体素子である。このような有機ＥＬ素子に２～２０Ｖ程度の比較的低い電圧を印加すると、有機化合物層に陰極から電子が注入され、陽極から正孔が注入される。この電子と正孔とが発光層において再結合し、形成された励起子が基底状態に戻る際にエネルギーを光として放出することにより発光が得られることが知られており、次世代の平面ディスプレイや照明装置として期待されている技術である。 The organic EL element is a thin film type having a single layer configuration or a multilayer configuration of an organic functional layer containing an organic light-emitting substance and having a thickness of only about 0.1 μm between a pair of anode and cathode formed on a film. It is an all-solid-state device. When a relatively low voltage of about 2 to 20 V is applied to such an organic EL element, electrons are injected from the cathode and holes are injected from the anode into the organic compound layer. It is known that light emission can be obtained by releasing energy as light when these electrons and holes recombine in the light emitting layer and the formed excitons return to the ground state. It is a technology expected as a lighting device.
　さらに、最近発見されたリン光発光を利用する有機ＥＬ素子では、従来の蛍光発光を利用する方式に比べ、原理的には約４倍の発光効率の実現が可能であることから、その材料開発をはじめとし、有機機能層の層構成や電極の研究開発が世界中で行われている。特に、地球温暖化防止策の１つとして、人類のエネルギー消費の多くの比率を占める照明器具への応用が検討されはじめ、従来の照明器具に置き換わりうる白色発光パネルの実用化に向けて、性能向上やコストダウンの試みが盛んに行われている。 Furthermore, the recently discovered organic EL device that utilizes phosphorescence can in principle achieve a luminous efficiency that is approximately four times that of conventional methods that utilize fluorescence. Research and development of organic functional layers and electrodes are being conducted all over the world. In particular, as one of the measures to prevent global warming, application to lighting fixtures, which account for a large proportion of human energy consumption, has begun to be studied. For the practical application of white light-emitting panels that can replace conventional lighting fixtures, There are many attempts to improve and reduce costs.
　照明用白色発光パネルにおいては、高効率及び長寿命が求められているが、特に長寿命化の観点においては、蛍光灯や白色ＬＥＤに対して性能が不十分であるのが現状であり、さらなる高効率化及び長寿命化の技術の開発が求められている。また、色温度の制御のために、スペクトルのシャープな発光材料も求められている。 The white light emitting panel for illumination is required to have high efficiency and long life, but in terms of extending the life, in particular, the performance is insufficient with respect to fluorescent lamps and white LEDs. There is a demand for the development of technologies for improving efficiency and extending the service life. In addition, a light-emitting material having a sharp spectrum is also required for controlling the color temperature.
　これらの問題を解決する方法として、発光材料として無機発光物質である「量子ドット」を用いる方法がある。 As a method of solving these problems, there is a method of using “quantum dots” that are inorganic light emitting materials as light emitting materials.
　量子ドット材料はシャープな発光スペクトルに加え、無機物であるために耐久性に優れ、また各種溶媒に分散が可能である特徴を持つことから、湿式塗布方式に適用が可能である。 Quantum dot material is not only a sharp emission spectrum but also an inorganic material, so it has excellent durability and can be dispersed in various solvents, so it can be applied to wet coating methods.
　例えば、非特許文献１においては、赤色の量子ドット材料を、Ｎ，Ｎ′－ジフェニル－Ｎ，Ｎ′－ビス（３－メチルフェニル）－（１，１′ビフェニル）－４，４′－ジアミンに分散させ、スピンコートして形成した素子において、シャープなスペクトルを有する赤色発光が確認されたことが報告されている。しかしながら、得られる発光効率は１ｌｍ／Ｗ程度と低いものであった。 For example, in Non-Patent Document 1, a red quantum dot material is represented by N, N′-diphenyl-N, N′-bis (3-methylphenyl)-(1,1′biphenyl) -4,4′-diamine. It has been reported that red light emission having a sharp spectrum was confirmed in an element formed by dispersing and spin coating. However, the luminous efficiency obtained was as low as about 1 lm / W.
　また、特許文献１においては、青色の量子ドットを使用して、青色の発光素子を得る方法が開示されているが、３００ｃｄの明るさを得るためには１１Ｖ程度の駆動電圧が必要であるなど、未だ高効率な青色の量子ドットを用いた発光素子は得られていない。これは、量子ドットに電荷を注入するホスト材料の電荷輸送性が低く、また準位が整合していないため、量子ドットへの電荷注入の効率が低いためと想定される。 Patent Document 1 discloses a method of obtaining a blue light emitting element using blue quantum dots, but a driving voltage of about 11 V is necessary to obtain a brightness of 300 cd. However, a light-emitting element using a blue quantum dot with high efficiency has not been obtained yet. This is presumably because the host material that injects charges into the quantum dots has a low charge transport property and the level is not matched, so the efficiency of charge injection into the quantum dots is low.
　また、特許文献２においては、リン光型有機ＥＬ素子において良好なホスト材料として知られる４，４′－ビス（カルバゾール－９－イル）ビフェニルを赤色発光量子ドットと組み合わせた有機ＥＬ素子が開示されており、また、特許文献３においては、ホスト材料として４，４′－ビス（カルバゾール－９－イル）－９，９－ジメチルフルオレンを用いて、緑色発光量子ドットと組み合わせた有機ＥＬ素子が開示されているが、青色発光量子ドットに適したホスト化合物については、設計指針に関する開示や示唆が認められない。 Patent Document 2 discloses an organic EL element in which 4,4′-bis (carbazol-9-yl) biphenyl, which is known as a good host material in a phosphorescent organic EL element, is combined with a red light emitting quantum dot. Patent Document 3 discloses an organic EL device in which 4,4′-bis (carbazol-9-yl) -9,9-dimethylfluorene is used as a host material and is combined with green light emitting quantum dots. However, there is no disclosure or suggestion regarding design guidelines for host compounds suitable for blue light emitting quantum dots.
　このように、発光効率及び素子寿命に優れ、演色性の高い有機ＥＬ素子に必要な青色発光量子ドットを用いた青色発光有機ＥＬ素子、及び緑・赤色リン光ドーパント等と組み合わせた白色発光有機ＥＬ素子は、未だ実現していないのが現状である。 As described above, a blue light-emitting organic EL element using blue light-emitting quantum dots, which is excellent in light emission efficiency and element lifetime, and a high color rendering property, and a white light-emitting organic EL combined with a green / red phosphorescent dopant, etc. The device is not yet realized.
国際公開第２０１０／１１４５４４号International Publication No. 2010/114544 国際公開第２００９／０４１５９４号International Publication No. 2009/041594 国際公開第２００９／０４１５９５号International Publication No. 2009/041595
　本発明は、上記問題に鑑みてなされたものであり、その解決課題は、高発光効率で長寿命の有機エレクトロルミネッセンス素子及びその製造方法を提供することであって、特に、演色性に優れ、低駆動電圧でも色度が安定した白色発光の有機エレクトロルミネッセンス素子及びその製造方法を提供することである。 The present invention has been made in view of the above problems, and its solution is to provide an organic electroluminescence device having a high luminous efficiency and a long lifetime and a method for producing the same, and particularly excellent in color rendering. To provide a white light-emitting organic electroluminescence device having stable chromaticity even at a low driving voltage and a method for manufacturing the same.
　本発明者は、上記課題に鑑み鋭意検討を進めた結果、少なくとも、陽極、正孔輸送層、リン光発光性化合物を含有する発光層、電子輸送層及び陰極を有する有機エレクトロルミネッセンス素子であって、発光波長が特定の範囲にある量子ドットと、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が特定の範囲にあるホスト化合物とを含有した構成の発光層を有する有機エレクトロルミネッセンス素子により、高発光効率及び長寿命で、演色性に優れ、低駆動電圧でも色度が安定した白色発光の有機エレクトロルミネッセンス素子を実現することができることを見出し、本発明に至った次第である。 As a result of intensive studies in view of the above problems, the present inventor is an organic electroluminescence device having at least an anode, a hole transport layer, a light emitting layer containing a phosphorescent compound, an electron transport layer, and a cathode. And an organic electroluminescence device having a light-emitting layer comprising a quantum dot having a light emission wavelength in a specific range and a host compound having a light emission wavelength belonging to a 0-0 transition band in the phosphorescence spectrum in a specific range Thus, it has been found that a white light-emitting organic electroluminescent element having high luminous efficiency and long life, excellent color rendering properties, and stable chromaticity even at a low driving voltage can be realized.
　すなわち、本発明の上記課題は、下記の手段により解決される。 That is, the above-mentioned problem of the present invention is solved by the following means.
　１．少なくとも、陽極、正孔輸送層、リン光発光性化合物を含有する発光層、電子輸送層及び陰極を有する有機エレクトロルミネッセンス素子であって、
　前記発光層が、発光波長が４１３～４７７ｎｍの範囲内にある量子ドットと、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４１３～４５９ｎｍの範囲内にあるホスト化合物とを含有することを特徴とする有機エレクトロルミネッセンス素子。 1. An organic electroluminescence device having at least an anode, a hole transport layer, a light emitting layer containing a phosphorescent compound, an electron transport layer and a cathode,
The light-emitting layer contains quantum dots having an emission wavelength in the range of 413 to 477 nm and a host compound having an emission wavelength in the range of 413 to 459 nm attributed to the 0-0 transition band in the phosphorescence spectrum. An organic electroluminescence device characterized by that.
　２．前記量子ドットの平均粒子径が、１～２０ｎｍの範囲内であることを特徴とする第１項に記載の有機エレクトロルミネッセンス素子。 2. 2. The organic electroluminescence device according to item 1, wherein the quantum dot has an average particle size in the range of 1 to 20 nm.
　３．前記前記量子ドットのアスペクト比（長軸径／短軸径）の値が、１．０～２．０の範囲内であることを特徴とする第１項又は第２項に記載の有機エレクトロルミネッセンス素子。 3. 3. The organic electroluminescence according to item 1 or 2, wherein the quantum dot has an aspect ratio (major axis diameter / minor axis diameter) in the range of 1.0 to 2.0. element.
　４．前記量子ドットが、少なくともＳｉ、Ｇｅ、ＧａＮ、ＧａＰ、ＣｄＳ、ＣｄＳｅ、ＣｄＴｅ、ＩｎＰ、ＩｎＮ、ＺｎＳ、Ｉｎ２Ｓ３、ＺｎＯ、ＣｄＯ又はこれらの混合物で構成されていることを特徴とする第１項から第３項までのいずれか一項に記載の有機エレクトロルミネッセンス素子。 4). The quantum dot is composed of at least Si, Ge, GaN, GaP, CdS, CdSe, CdTe, InP, InN, ZnS, In 2 S 3 , ZnO, CdO, or a mixture thereof. The organic electroluminescent element according to any one of items 1 to 3.
　５．前記ホスト化合物の分子量が、５００～１０００の範囲内であることを特徴とする第１項から第４項までのいずれか一項に記載の有機エレクトロルミネッセンス素子。 5. Item 5. The organic electroluminescence device according to any one of Items 1 to 4, wherein the host compound has a molecular weight in the range of 500 to 1,000.
　６．前記発光層が、前記ホスト化合物として、下記一般式（１）で表される化合物を含有することを特徴とする第１項から第５項までのいずれか一項に記載の有機エレクトロルミネッセンス素子。 6. The said light emitting layer contains the compound represented by following General formula (1) as said host compound, The organic electroluminescent element as described in any one of Claim 1-5 characterized by the above-mentioned.
Figure JPOXMLDOC01-appb-C000003
  
〔式中、Ｘは、ＮＲ′、酸素原子、硫黄原子、ＣＲ′Ｒ″、又はＳｉＲ′Ｒ″を表す。ｙ１及びｙ２は、各々ＣＲ′又は窒素原子を表す。Ｒ′及びＲ″は、各々水素原子又は置換基を表す。Ａｒ１及びＡｒ２は、各々芳香環を表し、それぞれ同一でも異なっていても良い。ｎは０～４の整数を表す。〕
　７．前記一般式（１）におけるＸが、ＮＲ′であることを特徴とする第６項に記載の有機エレクトロルミネッセンス素子。
Figure JPOXMLDOC01-appb-C000003
[Wherein, X represents NR ′, an oxygen atom, a sulfur atom, CR′R ″, or SiR′R ″. y 1 and y 2 each represent CR ′ or a nitrogen atom. R ′ and R ″ each represent a hydrogen atom or a substituent. Ar 1 and Ar 2 each represent an aromatic ring, which may be the same or different. N represents an integer of 0 to 4.]
7). 7. The organic electroluminescence device according to item 6, wherein X in the general formula (1) is NR ′.
　８．前記一般式（１）におけるＸが、酸素原子であることを特徴とする第６項に記載の有機エレクトロルミネッセンス素子。 8. X in the said General formula (1) is an oxygen atom, The organic electroluminescent element of Claim 6 characterized by the above-mentioned.
　９．前記一般式（１）で表される化合物が、下記一般式（２）で表される化合物であることを特徴とする第６項から第８項までのいずれか一項に記載の有機エレクトロルミネッセンス素子。 9. 9. The organic electroluminescence according to any one of items 6 to 8, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2): element.
Figure JPOXMLDOC01-appb-C000004
  
〔式中、Ａｒ３～Ａｒ５は、各々芳香環を表し、それぞれ同一でも異なっていても良い。ｎ１は、０～４の整数を表し、ｎ２は、０～５の整数を表す。〕
　１０．前記発光層に、更にリン光スペクトルにおける０－０遷移バンドに帰属される発光波長が、４９６～８２７ｎｍの範囲内にあるリン光発光ドーパントを含有することを特徴とする第１項から第９項までのいずれか一項に記載の有機エレクトロルミネッセンス素子。
Figure JPOXMLDOC01-appb-C000004
[Wherein Ar 3 to Ar 5 each represents an aromatic ring and may be the same or different from each other. n1 represents an integer of 0 to 4, and n2 represents an integer of 0 to 5. ]
10. Items 1 to 9 characterized in that the light emitting layer further contains a phosphorescent dopant whose emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum is in the range of 496 to 827 nm. The organic electroluminescent element as described in any one of the above.
　１１．少なくとも、陽極、正孔輸送層、リン光発光性化合物を含有する発光層、電子輸送層及び陰極を有する有機エレクトロルミネッセンス素子の製造方法であって、
　前記発光層に、発光波長が４１３～４７７ｎｍの範囲にある量子ドットと、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４１３～４５９ｎｍの範囲にあるホスト化合物とを含有させ、
　前記発光層を塗布方式で形成し、前記発光層形成用塗布液に、沸点が１００～１５０℃の範囲内にある溶媒を含有せしめることを特徴とする有機エレクトロルミネッセンス素子の製造方法。 11. At least an anode, a hole transport layer, a light emitting layer containing a phosphorescent compound, an electron transport layer and a method for producing an organic electroluminescent device having a cathode,
The light emitting layer contains a quantum dot having an emission wavelength in the range of 413 to 477 nm and a host compound having an emission wavelength belonging to the 0-0 transition band in the phosphorescence spectrum in the range of 413 to 459 nm.
A method for producing an organic electroluminescence device, wherein the light emitting layer is formed by a coating method, and a solvent having a boiling point in the range of 100 to 150 ° C. is contained in the coating solution for forming a light emitting layer.
　本発明の上記手段に示したように、有機エレクトロルミネッセンス素子を構成する発光層において、発光波長が４１３～４７７ｎｍの範囲にある量子ドットと、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４１３～４５９ｎｍの範囲内にあるホスト化合物とを用いることにより、量子ドットに効率よく励起子を注入することができるようになり、その結果、高い発光効率が得られ、また非発光過程による熱的な発光素子へのダメージも抑制される結果、高効率で、かつ長寿命な有機ＥＬ素子を提供することができる。特に、従来公知の方法に従った組み合わせでは、極めて難しかった演色性が高く、低駆動電圧で色度が安定した白色発光の有機エレクトロルミネッセンス素子を提供することができる。 As shown in the above means of the present invention, in the light emitting layer constituting the organic electroluminescence device, the quantum dots having an emission wavelength in the range of 413 to 477 nm and the emission attributed to the 0-0 transition band in the phosphorescence spectrum By using a host compound having a wavelength in the range of 413 to 459 nm, it becomes possible to efficiently inject excitons into the quantum dots, and as a result, high luminous efficiency can be obtained, and due to non-luminescent processes. As a result of suppressing damage to the thermal light-emitting element, an organic EL element having high efficiency and a long life can be provided. In particular, it is possible to provide a white light-emitting organic electroluminescence device having a high color rendering property, which has been extremely difficult with a combination according to a conventionally known method, and having a stable chromaticity at a low driving voltage.
本発明の有機エレクトロルミネッセンス素子の構成の一例を示す概略断面図Schematic sectional view showing an example of the configuration of the organic electroluminescence element of the present invention 本発明の有機エレクトロルミネッセンス素子の他の構成の一例を示す概略断面図Schematic sectional view showing an example of another configuration of the organic electroluminescence element of the present invention
　本発明の有機エレクトロルミネッセンス素子は、少なくとも、陽極、正孔輸送層、リン光発光性化合物を含有する発光層、電子輸送層及び陰極を有し、該発光層が、発光波長が４１３～４７７ｎｍの範囲内にある量子ドットと、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４１３～４５９ｎｍの範囲に内あるホスト化合物とを含有することを特徴とし、高発光効率及び長寿命で、演色性に優れ、かつ低駆動電圧でも色度が安定した白色発光の有機エレクトロルミネッセンス素子を実現することができる。この特徴は、請求項１から請求項１１に係る発明に共通する技術的特徴である。 The organic electroluminescence device of the present invention has at least an anode, a hole transport layer, a light emitting layer containing a phosphorescent compound, an electron transport layer and a cathode, and the light emitting layer has an emission wavelength of 413 to 477 nm. Characterized in that it contains a quantum dot in the range and a host compound in which the emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum is in the range of 413 to 459 nm, and has high luminous efficiency and long lifetime. In addition, it is possible to realize a white light-emitting organic electroluminescence element that is excellent in color rendering and stable in chromaticity even at a low driving voltage. This feature is a technical feature common to the inventions according to claims 1 to 11.
　本発明の実施態様としては、本発明の目的とする効果をより発現できる観点から、本発明に係る発光波長が４１３～４７７ｎｍの範囲内にある量子ドットの特性として、量子ドットの平均粒子径が、１～２０ｎｍの範囲内であることが好ましい。また、量子ドットのアスペクト比（長軸径／短軸径）の値として、１．０～２．０の範囲内であることが好ましい。また、適用する量子ドットとして、少なくともＳｉ、Ｇｅ、ＧａＮ、ＧａＰ、ＣｄＳ、ＣｄＳｅ、ＣｄＴｅ、ＩｎＰ、ＩｎＮ、ＺｎＳ、Ｉｎ２Ｓ３、ＺｎＯ、ＣｄＯ又はこれらの混合物で構成されていることが好ましい。 As an embodiment of the present invention, from the viewpoint of more manifesting the intended effect of the present invention, the quantum dot has an average particle diameter as a characteristic of a quantum dot having an emission wavelength in the range of 413 to 477 nm according to the present invention. It is preferably in the range of 1 to 20 nm. The aspect ratio (major axis diameter / minor axis diameter) of the quantum dots is preferably in the range of 1.0 to 2.0. Further, the quantum dots to be applied are preferably composed of at least Si, Ge, GaN, GaP, CdS, CdSe, CdTe, InP, InN, ZnS, In 2 S 3 , ZnO, CdO, or a mixture thereof.
　また、本発明に係リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４１３～４５９ｎｍの範囲内にあるホスト化合物としては、ホスト化合物の分子量が、５００～１０００の範囲内であることが好ましい。また、発光層が、ホスト化合物として、前記一般式（１）で表される化合物を含有することが好ましい。また、本発明に係る一般式（１）で表される化合物においては、ＸがＮＲ′又は酸素原子であることが好ましい。 The host compound having an emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum according to the present invention in the range of 413 to 459 nm should have a molecular weight of the host compound in the range of 500 to 1000. Is preferred. Moreover, it is preferable that a light emitting layer contains the compound represented by the said General formula (1) as a host compound. In the compound represented by the general formula (1) according to the present invention, X is preferably NR ′ or an oxygen atom.
　また、更には、前記一般式（１）で表される化合物が、前記一般式（２）で表される化合物であることが好ましい。 Furthermore, it is preferable that the compound represented by the general formula (1) is a compound represented by the general formula (2).
　更には、本発明の有機ＥＬ素子を構成する発光層が、更にリン光スペクトルにおける０－０遷移バンドに帰属する発光波長が、４９６～８２７ｎｍの範囲内にあるリン光発光ドーパントを含有することが好ましい。 Furthermore, the light emitting layer constituting the organic EL device of the present invention may further contain a phosphorescent dopant whose emission wavelength belonging to the 0-0 transition band in the phosphorescence spectrum is in the range of 496 to 827 nm. preferable.
　また、本発明の有機ＥＬ素子を製造する方法としては、発光層が塗布方式で形成し、該発光層の形成用塗布液が、沸点が１００～１５０℃の範囲内にある溶媒を含有することを特徴とする。 Further, as a method for producing the organic EL device of the present invention, the light emitting layer is formed by a coating method, and the coating liquid for forming the light emitting layer contains a solvent having a boiling point in the range of 100 to 150 ° C. It is characterized by.
　なお、本発明において、「量子ドット」とは、電子（及び正孔）を微小な空間に閉じ込めるために形成した直径が数～数十ｎｍの半導体微結晶であって、量子サイズ効果を発現する微結晶をいう。 In the present invention, a “quantum dot” is a semiconductor microcrystal having a diameter of several to several tens of nm formed to confine electrons (and holes) in a minute space, and exhibits a quantum size effect. It refers to microcrystals.
　また、「量子ドットのバンドギャップ」とは、量子ドットの価電子帯と伝導帯とのエネルギー差（エネルギーギャップ）をいう。 Also, “band gap of quantum dots” refers to the energy difference (energy gap) between the valence band and the conduction band of the quantum dots.
　また、「ホスト化合物、リン光発光ドーパント等のバンドギャップ」とは、最高被占分子軌道（ＨＯＭＯ）のエネルギー準位と最低空分子軌道（ＬＵＭＯ）のエネルギー準位とのエネルギー差（エネルギーギャップ）をいう。 “Band gaps of host compounds, phosphorescent dopants, etc.” mean the energy difference (energy gap) between the energy level of the highest occupied molecular orbital (HOMO) and the energy level of the lowest unoccupied molecular orbital (LUMO). Say.
　本発明に係る量子ドットは、発光波長が４１３～４７７ｎｍの範囲内にあることを特徴とするが、バンドギャップで表示すると、２．６～３．０ｅＶの範囲内である。 The quantum dots according to the present invention are characterized in that the emission wavelength is in the range of 413 to 477 nm, but in the band gap, it is in the range of 2.6 to 3.0 eV.
　また、本発明に係るホスト化合物は、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４１３～４５９ｎｍの範囲内にあることを特徴とするが、バンドギャップで表示すると、２．７～３．０ｅＶの範囲内である。 In addition, the host compound according to the present invention is characterized in that the emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum is in the range of 413 to 459 nm. Within the range of ~ 3.0 eV.
　以下、本発明とその構成要素、及び本発明を実施するための形態・態様について詳細な説明をする。なお、以下の説明において示す「～」は、その前後に記載される数値を下限値及び上限値として含む意味で使用する。 Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the following description, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
　《有機ＥＬの構成》
　図１に、本発明の有機エレクトロルミネッセンス素子の構成の一例を示す概略断面図を示す。 << Organic EL structure >>
In FIG. 1, the schematic sectional drawing which shows an example of a structure of the organic electroluminescent element of this invention is shown.
　図１において、本発明の好ましい実施形態に係る有機ＥＬ素子１００は、可撓性支持基板１を有している。可撓性支持基板１上には陽極２が形成され、陽極２上には有機機能層２０が形成され、有機機能層２０上には陰極８が形成されている。 1, an organic EL device 100 according to a preferred embodiment of the present invention has a flexible support substrate 1. An anode 2 is formed on the flexible support substrate 1, an organic functional layer 20 is formed on the anode 2, and a cathode 8 is formed on the organic functional layer 20.
　有機機能層２０とは、陽極２と陰極８との間に設けられている有機ＥＬ素子１００を構成する各層をいう。 The organic functional layer 20 refers to each layer constituting the organic EL element 100 provided between the anode 2 and the cathode 8.
　有機機能層２０には、例えば、正孔注入層３、正孔輸送層４、発光層５、電子輸送層６、電子注入層７が含まれ、そのほかに正孔ブロック層や電子ブロック層等が含まれてもよい。 The organic functional layer 20 includes, for example, a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, an electron injection layer 7, and in addition, a hole block layer, an electron block layer, and the like. May be included.
　可撓性支持基板１上の陽極２，有機機能層２０，陰極８は封止接着剤９を介して可撓性封止部材１０によって封止されている。 The anode 2, the organic functional layer 20, and the cathode 8 on the flexible support substrate 1 are sealed with a flexible sealing member 10 through a sealing adhesive 9.
　なお、有機ＥＬ素子１００のこれらの層構造（図１参照）は、単に好ましい有機ＥＬ素子ＥＬ素子構成の一例を示したものであり、本発明は図１に例示した構成にのみ限定されない。本発明の有機ＥＬ素子のその他の代表的な構成として、例えば、下記（ｉ）～（viii）に例示するような層構造を挙げることができる。 In addition, these layer structures (refer FIG. 1) of the organic EL element 100 show an example of a preferable organic EL element EL element structure, and this invention is not limited only to the structure illustrated in FIG. Other typical configurations of the organic EL device of the present invention include, for example, layer structures as exemplified in the following (i) to (viii).
　（ｉ）可撓性支持基板／陽極／発光層／電子輸送層／陰極／熱伝導層／封止用接着剤／封止部材
　（ii）可撓性支持基板／陽極／正孔輸送層／発光層／電子輸送層／陰極／熱伝導層／封止用接着剤／封止部材
　（iii）可撓性支持基板／陽極／正孔輸送層／発光層／正孔ブロック層／電子輸送層／陰極／熱伝導層／封止用接着剤／封止部材
　（iv）可撓性支持基板／陽極／正孔輸送層／発光層／正孔ブロック層／電子輸送層／陰極バッファー層／陰極／熱伝導層／封止用接着剤／封止部材
　（ｖ）可撓性支持基板／陽極／陽極バッファー層／正孔輸送層／発光層／正孔ブロック層／電子輸送層／陰極バッファー層／陰極／熱伝導層／封止用接着剤／封止部材
　（vi）ガラス支持体／陽極／正孔注入層／発光層／電子注入層／陰極／封止部材
　（vii）ガラス支持体／陽極／正孔注入層／正孔輸送層／発光層／電子注入層／陰極／封止部材
　（viii）ガラス支持体／陽極／正孔注入層／正孔輸送層／発光層／電子輸送層／電子注入層／陰極／封止部材
　《有機ＥＬ素子の各構成層》
　［１］有機機能層
　次いで、本発明の有機ＥＬ素子を構成する有機機能層の詳細について説明する。 (I) Flexible support substrate / anode / light emitting layer / electron transport layer / cathode / thermal conductive layer / sealing adhesive / sealing member (ii) Flexible support substrate / anode / hole transport layer / light emission Layer / electron transport layer / cathode / thermal conductive layer / sealing adhesive / sealing member (iii) flexible support substrate / anode / hole transport layer / light emitting layer / hole block layer / electron transport layer / cathode / Thermal conductive layer / sealing adhesive / sealing member (iv) flexible support substrate / anode / hole transport layer / light emitting layer / hole block layer / electron transport layer / cathode buffer layer / cathode / heat conduction Layer / adhesive for sealing / sealing member (v) flexible support substrate / anode / anode buffer layer / hole transport layer / light emitting layer / hole block layer / electron transport layer / cathode buffer layer / cathode / heat Conductive layer / adhesive for sealing / sealing member (vi) glass support / anode / hole injection layer / light emitting layer / electron injection layer / cathode / sealing member (vii) glass Holder / anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode / sealing member (viii) glass support / anode / hole injection layer / hole transport layer / light emitting layer / electron Transport layer / electron injection layer / cathode / sealing member << each constituent layer of organic EL element >>
[1] Organic Functional Layer Next, details of the organic functional layer constituting the organic EL element of the present invention will be described.
　〔１〕注入層
　本発明の有機ＥＬ素子においては、注入層は必要に応じて設けることができる。注入層としては正孔注入層と電子注入層があり、上記の如く陽極と発光層又は正孔輸送層の間、及び陰極と発光層又は電子輸送層との間に存在させてもよい。 [1] Injection layer In the organic EL device of the present invention, an injection layer can be provided as necessary. As the injection layer, there are a hole injection layer and an electron injection layer. As described above, the injection layer may exist between the anode and the light emitting layer or the hole transport layer, and between the cathode and the light emitting layer or the electron transport layer.
　本発明でいう注入層とは、駆動電圧低下や発光輝度向上のために電極と有機機能層間に設けられる層で、「有機ＥＬ素子とその工業化最前線（１９９８年１１月３０日エヌ・ティー・エス社発行）」の第２編第２章「電極材料」（１２３～１６６頁）に詳細に記載されており、正孔注入層と電子注入層とがある。 The injection layer referred to in the present invention is a layer provided between the electrode and the organic functional layer in order to lower the driving voltage and improve the light emission luminance. “The organic EL element and its industrialization front line (November 30, 1998, NT. 2) Chapter 2 “Electrode Materials” (pages 123 to 166) of “Part 2” of S. Co., Ltd.) and includes a hole injection layer and an electron injection layer.
　正孔注入層は、例えば、特開平９－４５４７９号公報、同９－２６００６２号公報、同８－２８８０６９号公報等にもその詳細が記載されており、正孔注入層に適用可能な正孔注入材料としては、トリアゾール誘導体、オキサジアゾール誘導体、イミダゾール誘導体、ピラゾリン誘導体及びピラゾロン誘導体、フェニレンジアミン誘導体、アリールアミン誘導体、アミノ置換カルコン誘導体、オキサゾール誘導体、スチリルアントラセン誘導体、フルオレノン誘導体、ヒドラゾン誘導体、スチルベン誘導体、シラザン誘導体等を含むポリマーやアニリン系共重合体、ポリアリールアルカン誘導体、又は導電性ポリマーが挙げられ、好ましくはポリチオフェン誘導体、ポリアニリン誘導体、ポリピロール誘導体であり、さらに好ましくはポリチオフェン誘導体である。 The details of the hole injection layer are described, for example, in JP-A-9-45479, JP-A-9-260062, and JP-A-8-288069. Injection materials include triazole derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives. , Polymers containing silazane derivatives, aniline copolymers, polyarylalkane derivatives, or conductive polymers, preferably polythiophene derivatives, polyaniline derivatives, polypyrrole derivatives, more preferably It is a thiophene derivative.
　電子注入層は、例えば、特開平６－３２５８７１号公報、同９－１７５７４号公報、同１０－７４５８６号公報等にその詳細が記載されており、具体的には、ストロンチウムやアルミニウム等に代表される金属バッファー層、フッ化リチウムに代表されるアルカリ金属化合物バッファー層、フッ化マグネシウムに代表されるアルカリ土類金属化合物バッファー層、酸化アルミニウムに代表される酸化物バッファー層等が挙げられる。 The details of the electron injection layer are described, for example, in JP-A-6-325871, JP-A-9-17574, and JP-A-10-74586, and specifically, strontium, aluminum and the like are representative. A metal buffer layer, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide.
　本発明においては、上記バッファー層（注入層）はごく薄い膜であることが望ましく、フッ化カリウム、フッ化ナトリウムであることが好ましく、その膜厚は０．１ｎｍ～５μｍ程度、好ましくは０．１～１００ｎｍ、さらに好ましくは０．５～１０ｎｍ、最も好ましくは０．５～４ｎｍである。 In the present invention, the buffer layer (injection layer) is desirably a very thin film, preferably potassium fluoride or sodium fluoride, and has a film thickness of about 0.1 nm to 5 μm, preferably 0.8. The thickness is 1 to 100 nm, more preferably 0.5 to 10 nm, and most preferably 0.5 to 4 nm.
　〔２〕正孔輸送層
　本発明において、正孔輸送層とは、正孔を輸送する機能を有する材料からなり、陽極より注入された正孔を発光層に伝達する機能を有していればよい。 [2] Hole transport layer In the present invention, the hole transport layer is made of a material having a function of transporting holes, and has a function of transmitting holes injected from the anode to the light emitting layer. Good.
　本発明の正孔輸送層の総膜厚については特に制限はないが、通常は５ｎｍ～５μｍの範囲内であり、より好ましくは２～５００ｎｍの範囲内であり、さらに好ましくは５～２００ｎｍの範囲内である。 The total film thickness of the hole transport layer of the present invention is not particularly limited, but is usually in the range of 5 nm to 5 μm, more preferably in the range of 2 to 500 nm, and still more preferably in the range of 5 to 200 nm. Is within.
　正孔輸送層に用いられる材料（以下、正孔輸送材料という）としては、正孔の注入性又は輸送性、電子の障壁性のいずれかを有していればよく、従来公知の化合物の中から任意のものを選択して用いることができる。 As a material used for the hole transport layer (hereinafter referred to as a hole transport material), any material that has either a hole injection property or a transport property or an electron barrier property may be used. Any one can be selected and used.
　例えば、ポルフィリン誘導体、フタロシアニン誘導体、オキサゾール誘導体、オキサジアゾール誘導体、トリアゾール誘導体、イミダゾール誘導体、ピラゾリン誘導体、ピラゾロン誘導体、フェニレンジアミン誘導体、ヒドラゾン誘導体、スチルベン誘導体、ポリアリールアルカン誘導体、トリアリールアミン誘導体、カルバゾール誘導体、インドロカルバゾール誘導体、イソインドール誘導体、アントラセンやナフタレン等のアセン系誘導体、フルオレン誘導体、フルオレノン誘導体、及びポリビニルカルバゾール、芳香族アミンを主鎖又は側鎖に導入した高分子材料又はオリゴマー、ポリシラン、導電性ポリマー又はオリゴマー（例えば、ＰＥＤＯＴ：ＰＳＳ（ポリ（３，４－エチレンジオキシチオフェン）－ポリスチレンスルホネート）、アニリン系共重合体、ポリアニリン、ポリチオフェン等）等が挙げられる。 For example, porphyrin derivatives, phthalocyanine derivatives, oxazole derivatives, oxadiazole derivatives, triazole derivatives, imidazole derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, hydrazone derivatives, stilbene derivatives, polyarylalkane derivatives, triarylamine derivatives, carbazole derivatives , Indolocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polyvinyl carbazole, polymer materials or oligomers with aromatic amines introduced into the main chain or side chain, polysilane, conductive Polymer or oligomer (eg, PEDOT: PSS (poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate) ), Aniline copolymers, polyaniline, and polythiophene, etc.) and the like.
　トリアリールアミン誘導体としては、α－ＮＰＤ（４，４′－ビス〔Ｎ－（１－ナフチル）－Ｎ－フェニルアミノ〕ビフェニル）に代表されるベンジジン型や、ＭＴＤＡＴＡ（４，４′，４″－トリス〔Ｎ－（３－メチルフェニル）－Ｎ－フェニルアミノ〕トリフェニルアミン）に代表されるスターバースト型、トリアリールアミン連結コア部にフルオレンやアントラセンを有する化合物等が挙げられる。 Examples of the triarylamine derivative include benzidine type represented by α-NPD (4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl), and MTDATA (4,4 ′, 4 ″). Examples include a starburst type represented by -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine), a compound having fluorene or anthracene in the triarylamine-linked core.
　また、特表２００３－５１９４３２号公報や特開２００６－１３５１４５号公報等に記載されているようなヘキサアザトリフェニレン誘導体も同様に正孔輸送材料として用いることができる。 In addition, hexaazatriphenylene derivatives such as those described in JP-T-2003-519432 and JP-A-2006-135145 can also be used as a hole transport material.
　更に、不純物をドープしたｐ性の高い正孔輸送層を用いることもできる。その例としては、特開平４－２９７０７６号公報、特開２０００－１９６１４０号公報、同２００１－１０２１７５号公報の各公報、Ｊ．Ａｐｐｌ．Ｐｈｙｓ．，９５，５７７３（２００４）等に記載されたものが挙げられる。 Furthermore, a hole transport layer having a high p property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, and JP-A-2001-102175. Appl. Phys. 95, 5773 (2004), and the like.
　また、特開平１１－２５１０６７号公報、Ｊ．Ｈｕａｎｇ　ｅｔ．ａｌ．著文献（Ａｐｐｌｉｅｄ　Ｐｈｙｓｉｃｓ　Ｌｅｔｔｅｒｓ　８０（２００２），ｐ．１３９）に記載されているような、所謂ｐ型正孔輸送材料やｐ型－Ｓｉ、ｐ型－ＳｉＣ等の無機化合物を用いることもできる。さらにＩｒ（ｐｐｙ）３に代表されるような中心金属にＩｒやＰｔを有するオルトメタル化有機金属錯体も好ましく用いられる。 Also, JP-A-11-251067, J. Org. Huang et. al. It is also possible to use so-called p-type hole transport materials and inorganic compounds such as p-type-Si and p-type-SiC as described in the literature (Applied Physics Letters 80 (2002), p. 139). Further, ortho-metalated organometallic complexes having Ir or Pt as the central metal represented by Ir (ppy) 3 are also preferably used.
　正孔輸送材料としては、上記のものを使用することができるが、トリアリールアミン誘導体、カルバゾール誘導体、インドロカルバゾール誘導体、アザトリフェニレン誘導体、有機金属錯体、芳香族アミンを主鎖又は側鎖に導入した高分子材料又はオリゴマー等が好ましく用いられる。 Although the above-mentioned materials can be used as the hole transport material, a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an azatriphenylene derivative, an organometallic complex, or an aromatic amine is introduced into the main chain or side chain. The polymer materials or oligomers used are preferably used.
　本発明の有機ＥＬ素子に用いられる、公知の好ましい正孔輸送材料の具体例としては、上記で挙げた文献の他、以下の文献に記載の化合物等が挙げられるが、本発明はこれらに限定されない。 Specific examples of known preferred hole transport materials used in the organic EL device of the present invention include the compounds described in the following documents in addition to the documents listed above, but the present invention is not limited thereto. Not.
　例えば、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．６９，２１６０（１９９６）、Ｊ．Ｌｕｍｉｎ．７２－７４，９８５（１９９７）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７８，６７３（２００１）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．９０，１８３５０３（２００７）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．９０，１８３５０３（２００７）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．５１，９１３（１９８７）、Ｓｙｎｔｈ．Ｍｅｔ．８７，１７１（１９９７）、Ｓｙｎｔｈ．Ｍｅｔ．９１，２０９（１９９７）、Ｓｙｎｔｈ．Ｍｅｔ．１１１，４２１（２０００）、ＳＩＤ　Ｓｙｍｐｏｓｉｕｍ　Ｄｉｇｅｓｔ，３７，９２３（２００６）、Ｊ．Ｍａｔｅｒ．Ｃｈｅｒｎ．３，３１９（１９９３）、Ａｄｖ．Ｍａｔｅｒ．６，６７７（１９９４）、Ｃｈｅｒｎ．Ｍａｔｅｒ．１５，３１４８（２００３）、米国特許公開第２００３０１６２０５３号明細書、米国特許公開第２００２０１５８２４２号明細書、米国特許公開第２００６０２４０２７９号明細書、米国特許公開第２００８０２２０２６５号明細書、米国特許第５０６１５６９号明細書、国際公開第２００７／００２６８３号、国際公開第２００９／０１８００９号、ＥＰ第６５０９５５号明細書、米国特許公開第２００８０１２４５７２号明細書、米国特許公開第２００７０２７８９３８号明細書、米国特許公開第２００８０１０６１９０号明細書、米国特許公開第２００８００１８２２１号明細書、国際公開第２０１２／１１５０３４号、特表２００３－５１９４３２号公報、特開２００６－１３５１４５号公報、米国特許出願番号１３／５８５９８１号明細書等である。 For example, Appl. Phys. Lett. 69, 2160 (1996), J. MoI. Lumin. 72-74,985 (1997), Appl. Phys. Lett. 78, 673 (2001), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 51, 913 (1987), Synth. Met. 87, 171 (1997), Synth. Met. 91, 209 (1997), Synth. Met. 111, 421 (2000), SID Symposium Digest, 37, 923 (2006), J. Am. Mater. Chern. 3,319 (1993), Adv. Mater. 6, 677 (1994), Chern. Mater. 15, 3148 (2003), U.S. Patent Publication No. 20030162053, U.S. Patent Publication No. 200201558242, U.S. Patent Publication No. 20060240279, U.S. Patent Publication No. 20080220265, U.S. Patent No. 5061569. , WO 2007/002683, WO 2009/018009, EP 650955, US Patent Publication No. 20080124572, US Patent Publication No. 2007078938, US Patent Publication No. 20080106190. US Patent Publication No. 20080018221, International Publication No. 2012/115034, Japanese Translation of PCT International Publication No. 2003-519432, Japanese Patent Application Laid-Open No. 2006-135145, US Patent Application No. 13/58598 No. is a specification and the like.
　正孔輸送材料は単独で用いてもよく、また複数種を併用して用いてもよい。 The hole transport material may be used alone or in combination of two or more.
　〔３〕電子輸送層
　本発明の有機ＥＬ素子の有機機能層を構成する電子輸送層とは、電子を輸送する機能を有する材料から構成され、広い意味で電子注入層、正孔ブロック層も電子輸送層のカテゴリーに含まれる。電子輸送層は、単層又は複数層設けることができる。 [3] Electron transport layer The electron transport layer constituting the organic functional layer of the organic EL device of the present invention is composed of a material having a function of transporting electrons, and in a broad sense, the electron injection layer and the hole blocking layer are also electrons. Included in the transport layer category. The electron transport layer can be provided as a single layer or a plurality of layers.
　単層の電子輸送層、あるいは複数の電子輸送層を構成する場合、発光層に対して陰極側に隣接する位置に形成される電子輸送層に適用することができる電子輸送材料（正孔ブロック材料を兼ねる）としては、陰極より注入された電子を発光層に伝達する機能を有していればよく、その材料としては従来公知の化合物の中から任意のものを選択して用いることができ、例えば、フルオレン誘導体、カルバゾール誘導体、アザカルバゾール誘導体、オキサジアゾール誘導体、トリアゾール誘導体、シロール誘導体、ピリジン誘導体、ピリミジン誘導体、８－キノリノール誘導体等の金属錯体等が挙げられる。 When a single electron transport layer or a plurality of electron transport layers are configured, an electron transport material (hole blocking material) that can be applied to an electron transport layer formed at a position adjacent to the cathode side with respect to the light emitting layer As long as it has a function of transmitting electrons injected from the cathode to the light-emitting layer, and the material can be selected from any conventionally known compounds and used. Examples thereof include metal complexes such as fluorene derivatives, carbazole derivatives, azacarbazole derivatives, oxadiazole derivatives, triazole derivatives, silole derivatives, pyridine derivatives, pyrimidine derivatives, 8-quinolinol derivatives, and the like.
　その他、メタルフリーもしくはメタルフタロシアニン、又はそれらの末端がアルキル基やスルホン酸基等で置換されているものも、電子輸送材料として好ましく用いることができる。 In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material.
　これらの中でも、カルバゾール誘導体、アザカルバゾール誘導体、ピリジン誘導体等が好ましく、その中でも、アザカルバゾール誘導体がより好ましい。 Of these, carbazole derivatives, azacarbazole derivatives, pyridine derivatives and the like are preferable, and among them, azacarbazole derivatives are more preferable.
　本発明の有機ＥＬ素子に用いることができる公知の好ましい電子輸送材料の具体例としては、以下の文献に記載の化合物等が挙げられるが、本発明はこれらに限定されない。 Specific examples of known preferable electron transport materials that can be used in the organic EL device of the present invention include compounds described in the following documents, but the present invention is not limited thereto.
　米国特許第６５２８１８７号明細書、米国特許第７２３０１０７号明細書、米国特許公開第２００５００２５９９３号明細書、米国特許公開第２００４００３６０７７号明細書、米国特許公開第２００９０１１５３１６号明細書、米国特許公開第２００９０１０１８７０号明細書、米国特許公開第２００９０１７９５５４号明細書、国際公開第２００３／０６０９５６号、国際公開第２００８／１３２０８５号、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７５，４（１９９９）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７９，４４９（２００１）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．８１，１６２（２００２）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．８１，１６２（２００２）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７９，１５６（２００１）、米国特許第７９６４２９３号明細書、米国特許公開第２００９０３０２０２号明細書、国際公開第２００４／０８０９７５号、国際公開第２００４／０６３１５９号、国際公開第２００５／０８５３８７号、国際公開第２００６／０６７９３１号、国際公開第２００７／０８６５５２号、国際公開第２００８／１１４６９０号、国際公開第２００９／０６９４４２号、国際公開第２００９／０６６７７９号、国際公開第２００９／０５４２５３号、国際公開第２０１１／０８６９３５号、国際公開第２０１０／１５０５９３号、国際公開第２０１０／０４７７０７号、ＥＰ第２３１１８２６号明細書、特開２０１０－２５１６７５号公報、特開２００９－２０９１３３号公報、特開２００９－１２４１１４号公報、特開２００８－２７７８１０号公報、特開２００６－１５６４４５号公報、特開２００５－３４０１２２号公報、特開２００３－４５６６２号公報、特開２００３－３１３６７号公報、特開２００３－２８２２７０号公報、国際公開第２０１２／１１５０３４号等である。 U.S. Patent No. 6,528,187, U.S. Patent No. 7,230,107, U.S. Patent Publication No. 20050025993, U.S. Patent Publication No. 2004036077, U.S. Patent Publication No. 200901115316, U.S. Patent Publication No. 200901870. U.S. Patent Publication No. 20090179554, International Publication No. 2003/060956, International Publication No. 2008/132805, Appl. Phys. Lett. 75, 4 (1999), Appl. Phys. Lett. 79, 449 (2001), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 79,156 (2001), U.S. Patent No. 7964293, U.S. Patent Publication No. 2009030202, International Publication No. 2004/080975, International Publication No. 2004/063159, International Publication No. 2005/085387, International Publication No. 2006/067931, International Publication No. 2007/086552, International Publication No. 2008/114690, International Publication No. 2009/066942, International Publication No. 2009/066779, International Publication No. 2009/054253, International Publication No. 2011 / 086935, International Publication No. 2010/150593, International Publication No. 2010/047707, EP No. 2311826, Japanese Unexamined Patent Publication No. 2010-251675, Japanese Unexamined Patent Publication No. 2009-209133, Japanese Unexamined Patent Publication No. 2009-124114. JP 2008-277810 A, JP 2006-156445 A, JP 2005-340122 A, JP 2003-45662 A, JP 2003-31367 A, JP 2003-282270 A, International Publication. No. 2012/115034.
　電子輸送層は、上記電子輸送材料を、例えば、スピンコート法、キャスト法、インクジェット法を含む印刷法、ＬＢ法等の公知の方法により、薄膜化することにより形成することができ、上記電子輸送材料とフッ化アルコール溶媒を含有する塗布液を用いたウェットプロセスにより形成することが好ましい。 The electron transport layer can be formed by thinning the electron transport material by a known method such as a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. It is preferably formed by a wet process using a coating solution containing a material and a fluorinated alcohol solvent.
　電子輸送層の膜厚については、特に制限はないが、通常は５ｎｍ～５μｍの範囲内であり、好ましくは５～２００ｎｍの範囲内である。電子輸送層は、上記材料の１種又は２種以上からなる単層構造であってもよい。 The thickness of the electron transport layer is not particularly limited, but is usually in the range of 5 nm to 5 μm, preferably in the range of 5 to 200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.
　また、不純物をゲスト材料としてドープしたｎ性の高い電子輸送層を用いることもできる。その例としては、特開平４－２９７０７６号公報、同１０－２７０１７２号公報、特開２０００－１９６１４０号公報、同２００１－１０２１７５号公報、Ｊ．Ａｐｐｌ．Ｐｈｙｓ．，９５，５７７３（２００４）等に記載された構成が挙げられる。 It is also possible to use an n-type electron transport layer doped with impurities as a guest material. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.
　本発明に係る電子輸送層には、有機物のアルカリ金属塩を含有することが好ましい。有機物の種類としては、特に制限はないが、例えば、ギ酸塩、酢酸塩、プロピオン酸、酪酸塩、吉草酸塩、カプロン酸塩、エナント酸塩、カプリル酸塩、シュウ酸塩、マロン酸塩、コハク酸塩、安息香酸塩、フタル酸塩、イソフタル酸塩、テレフタル酸塩、サリチル酸塩、ピルビン酸塩、乳酸塩、リンゴ酸塩、アジピン酸塩、メシル酸塩、トシル酸塩、ベンゼンスルホン酸塩が挙げられ、好ましくはギ酸塩、酢酸塩、プロピオン酸塩、酪酸塩、吉草酸塩、カプロン酸塩、エナント酸塩、カプリル酸塩、シュウ酸塩、マロン酸塩、コハク酸塩、安息香酸塩等が挙げられる。より好ましくは、ギ酸塩、酢酸塩、プロピオン酸塩、酪酸塩等の脂肪族カルボン酸のアルカリ金属塩であり、脂肪族カルボン酸の炭素数が４以下であることが好ましく、最も好ましくは酢酸塩である。 The electron transport layer according to the present invention preferably contains an organic alkali metal salt. The type of organic substance is not particularly limited, but for example, formate, acetate, propionic acid, butyrate, valerate, caprate, enanthate, caprylate, oxalate, malonate, Succinate, benzoate, phthalate, isophthalate, terephthalate, salicylate, pyruvate, lactate, malate, adipate, mesylate, tosylate, benzenesulfonate Preferably, formate, acetate, propionate, butyrate, valerate, caprate, enanthate, caprylate, oxalate, malonate, succinate, benzoate Etc. More preferably, it is an alkali metal salt of an aliphatic carboxylic acid such as formate, acetate, propionate, butyrate, etc., and the aliphatic carboxylic acid preferably has 4 or less carbon atoms, most preferably acetate. It is.
　有機物のアルカリ金属塩のアルカリ金属の種類としては、特に制限はないが、Ｎａ、Ｋ、Ｃｓが挙げられ、好ましくはＫ、Ｃｓ、さらに好ましくはＣｓである。有機物のアルカリ金属塩としては、前記有機物とアルカリ金属の組み合わせが挙げられ、好ましくは、ギ酸Ｌｉ、ギ酸Ｋ、ギ酸Ｎａ、ギ酸Ｃｓ、酢酸Ｌｉ、酢酸Ｋ、酢酸Ｎａ、酢酸Ｃｓ、プロピオン酸Ｌｉ、プロピオン酸Ｎａ、プロピオン酸Ｋ、プロピオン酸Ｃｓ、シュウ酸Ｌｉ、シュウ酸Ｎａ、シュウ酸Ｋ、シュウ酸Ｃｓ、マロン酸Ｌｉ、マロン酸Ｎａ、マロン酸Ｋ、マロン酸Ｃｓ、コハク酸Ｌｉ、コハク酸Ｎａ、コハク酸Ｋ、コハク酸Ｃｓ、安息香酸Ｌｉ、安息香酸Ｎａ、安息香酸Ｋ、安息香酸Ｃｓ、より好ましくは酢酸Ｌｉ、酢酸Ｋ、酢酸Ｎａ、酢酸Ｃｓ、最も好ましくは酢酸Ｃｓである。 The kind of alkali metal of the organic alkali metal salt is not particularly limited, and examples thereof include Na, K, and Cs, preferably K, Cs, and more preferably Cs. Examples of the alkali metal salt of the organic substance include a combination of the organic substance and the alkali metal, preferably, formic acid Li, formic acid K, formic acid Na, formic acid Cs, acetic acid Li, acetic acid K, Na acetate, acetic acid Cs, propionic acid Li, Propionic acid Na, propionic acid K, propionic acid Cs, oxalic acid Li, oxalic acid Na, oxalic acid K, oxalic acid Cs, malonic acid Li, malonic acid Na, malonic acid K, malonic acid Cs, succinic acid Li, succinic acid Na, succinic acid K, succinic acid Cs, benzoic acid Li, benzoic acid Na, benzoic acid K, benzoic acid Cs, more preferably Li acetate, K acetate, Na acetate, Cs acetate, most preferably Cs acetate.
　これら有機物のアルカリ金属塩の含有量は、添加する電子輸送層１００質量％に対し、好ましくは１．５～３５質量％の範囲内であり、より好ましくは３～２５質量％の範囲内であり、最も好ましくは５～１５質量％の範囲内である。 The content of the alkali metal salt of these organic substances is preferably in the range of 1.5 to 35% by mass, more preferably in the range of 3 to 25% by mass with respect to 100% by mass of the electron transport layer to be added. Most preferably, it is in the range of 5 to 15% by mass.
　〔４〕発光層
　本発明の有機ＥＬ素子を構成する発光層は、電極又は電子輸送層、正孔輸送層から注入されてくる電子と正孔とが再結合して発光する層であり、発光する部分は発光層の層内であっても発光層と隣接層との界面であってもよい。 [4] Light-emitting layer The light-emitting layer constituting the organic EL device of the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and emits light. The portion to be formed may be in the light emitting layer or at the interface between the light emitting layer and the adjacent layer.
　本発明に係る発光層は、発光波長が４１３～４７７ｎｍの範囲内にある量子ドットと、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４１３～４５９ｎｍの範囲内にあるホスト化合物とを含有する要件を満たしていれば、その他の構成要件には特に制限はない。 The light emitting layer according to the present invention comprises a quantum dot having an emission wavelength in the range of 413 to 477 nm, and a host compound having an emission wavelength in the range of 413 to 459 nm attributed to the 0-0 transition band in the phosphorescence spectrum. There are no particular restrictions on the other constituents as long as they satisfy the requirements containing.
　また、同一の発光スペクトルや発光極大波長を有する層が複数層あってもよい。また、各発光層間には非発光性の中間層を有していることが好ましい。 Also, there may be a plurality of layers having the same emission spectrum or emission maximum wavelength. Moreover, it is preferable to have a non-light emitting intermediate | middle layer between each light emitting layer.
　本発明における発光層の膜厚の総和は、１～１００ｎｍの範囲内にあることが好ましく、さらに好ましくは、より低い駆動電圧を得ることができることから、５０ｎｍ以下である。なお、本発明でいう発光層の膜厚の総和とは、発光層間に非発光性の中間層が存在する場合には、当該中間層も含む膜厚をいう。 In the present invention, the total thickness of the light emitting layers is preferably in the range of 1 to 100 nm, and more preferably 50 nm or less because a lower driving voltage can be obtained. In addition, the sum total of the film thickness of the light emitting layer as used in this invention means the film thickness also including the said intermediate | middle layer, when a nonluminous intermediate | middle layer exists between light emitting layers.
　個々の発光層の膜厚としては、１～５０ｎｍの範囲内に調整することが好ましい。 The film thickness of each light emitting layer is preferably adjusted within the range of 1 to 50 nm.
　個々の発光層は、青、緑、赤の各色発光を示しても良く、各発光層の膜厚の関係については、特に制限はない。 The individual light emitting layers may exhibit blue, green, and red light emission, and there is no particular limitation on the relationship of the film thickness of each light emitting layer.
　発光層の形成には、後述する発光材料やホスト化合物を、例えば、真空蒸着法、スピンコート法、キャスト法、ＬＢ法、インクジェット法等の公知の薄膜化法により製膜して形成することができる。 For the formation of the light emitting layer, a light emitting material or a host compound, which will be described later, is formed by forming a film by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink jet method. it can.
　本発明においては、各発光層には複数の発光材料を混合してもよく、またリン光発光材料と蛍光発光材料を同一発光層中に混合して用いてもよい。 In the present invention, a plurality of light emitting materials may be mixed in each light emitting layer, or a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer.
　本発明においては、発光層の構成として、ホスト化合物、発光材料（発光ドーパント化合物ともいう）を含有し、発光材料により発光させることが好ましい。 In the present invention, the light emitting layer preferably contains a host compound and a light emitting material (also referred to as a light emitting dopant compound) and emits light with the light emitting material.
　（４．１）ホスト化合物
　本発明の有機ＥＬ素子を構成する発光層に適用するホスト化合物は、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４１３～４５９ｎｍ（２．７～３．０ｅＶ）の範囲内という発光波長の短い化合物であり、すなわち三重項エネルギーの高い化合物であるにあることを特徴とするものである。より好ましくは、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４３０～４５５ｎｍの範囲内にある化合物であり、更に好ましくは４４０～４５０ｎｍにある化合物である。 (4.1) Host Compound The host compound applied to the light emitting layer constituting the organic EL device of the present invention has an emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum of 413 to 459 nm (2.7 to 3). .0 eV), a compound having a short emission wavelength, that is, a compound having a high triplet energy. More preferred are compounds having an emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum in the range of 430 to 455 nm, and more preferred are compounds having a wavelength of 440 to 450 nm.
　このように、三重項のエネルギー準位においても、量子ドット化合物よりも広いバンドギャップのホスト化合物を用いることで、量子ドット化合物へのキャリアの注入や励起子の閉じ込めが効率的なものとなり、高効率の発光、及び熱的失活過程の低減による発光の長寿命化効果を得ることができる。 In this way, even in the triplet energy level, by using a host compound having a wider band gap than the quantum dot compound, carrier injection into the quantum dot compound and exciton confinement become efficient. Efficient light emission and the effect of extending the life of light emission by reducing the thermal deactivation process can be obtained.
　本発明に係るホスト化合物としては、上記条件を満たす化合物であれば特に制限はない。 The host compound according to the present invention is not particularly limited as long as it satisfies the above conditions.
　本発明に係るホスト化合物のリン光スペクトルにおける０－０遷移バンドに帰属される発光波長は、下記の方法により求めることができる。 The emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum of the host compound according to the present invention can be determined by the following method.
　はじめに、測定対象であるホスト化合物を、脱酸素されたエタノール／メタノール＝４／１（ｖｏｌ／ｖｏｌ）の混合溶媒に溶かし、リン光測定用セルに入れた後、液体窒素温度７７Ｋで励起光を照射し、励起光を照射した後、１００ｍｓでの発光スペクトルを測定する。リン光は蛍光に比べ発光寿命が長いため、１００ｍｓ後に残存する光はほぼリン光であると考えることができる。なお、リン光寿命が１００ｍｓより短い化合物に対しては遅延時間を短くして測定しても構わないが、蛍光と区別できなくなるほど遅延時間を短くしてしまうとリン光と蛍光が分離できない問題が生じるため、その分離が可能な遅延時間を選択する必要がある。 First, a host compound to be measured is dissolved in a deoxygenated mixed solvent of ethanol / methanol = 4/1 (vol / vol), put into a phosphorescence measurement cell, and then excited light is emitted at a liquid nitrogen temperature of 77K. After irradiating and irradiating excitation light, an emission spectrum at 100 ms is measured. Since phosphorescence has a longer emission lifetime than fluorescence, it can be considered that light remaining after 100 ms is almost phosphorescence. For compounds with a phosphorescence lifetime shorter than 100 ms, measurement may be performed with a short delay time, but phosphorescence and fluorescence cannot be separated if the delay time is so short that it cannot be distinguished from fluorescence. Therefore, it is necessary to select a delay time that can be separated.
　また、上記溶媒系で溶解できないホスト化合物については、そのホスト化合物を溶解しうる任意の溶媒を使用してもよい。実質上、上記測定法ではリン光波長の溶媒効果はごくわずかなので問題ないと考えられる。 For the host compound that cannot be dissolved in the solvent system, any solvent that can dissolve the host compound may be used. In practice, the above-described measurement method is considered to have no problem because the solvent effect of the phosphorescence wavelength is negligible.
　次に、０－０遷移バンドの測定方法であるが、本発明においては、上記測定法で得られたリン光スペクトルチャートのなかで、最も短波長側に現れる発光極大波長をもって０－０遷移バンドと定義する。 Next, a method for measuring the 0-0 transition band will be described. In the present invention, the 0-0 transition band having the maximum emission wavelength that appears on the shortest wavelength side in the phosphorescence spectrum chart obtained by the above measurement method. It is defined as
　リン光スペクトルは通常強度が弱いことが多いため、拡大するとノイズとピークの判別が難しくなるケースがある。このような場合には、励起光照射中の発光スペクトル（便宜上、これを定常光スペクトルという。）を拡大し、励起光を照射した後、１００ｍｓ後の発光スペクトル（便宜上、これをリン光スペクトルという。）と重ねあわせ、リン光スペクトルに由来する定常光スペクトル部分から、リン光スペクトルのピーク波長を読みとることにより、０－０遷移バンドを決定することができる。 Since the phosphorescence spectrum is usually weak in intensity, it may become difficult to distinguish between noise and peak when enlarged. In such a case, the emission spectrum during excitation light irradiation (for convenience, this is referred to as a steady light spectrum) is expanded, and after the excitation light is irradiated, the emission spectrum after 100 ms (for convenience, this is referred to as a phosphorescence spectrum). The 0-0 transition band can be determined by reading the peak wavelength of the phosphorescence spectrum from the stationary light spectrum portion derived from the phosphorescence spectrum.
　また、リン光スペクトルをスムージング処理することでノイズとピークを分離し、ピーク波長を読みとることもできる。なお、スムージング処理としては、Ｓａｖｉｔｚｋｙ＆Ｇｏｌａｙの平滑化法等を適用することができる。 Also, it is possible to separate the noise and peak by smoothing the phosphorescence spectrum and read the peak wavelength. As the smoothing process, a smoothing method of Savitzky & Golay can be applied.
　上記測定で用いることのできる測定装置としては、日立ハイテク製の蛍光光度計Ｆ４５００等を挙げることができる。 As a measuring apparatus that can be used in the above measurement, a fluorometer F4500 manufactured by Hitachi High-Technology Corporation can be exemplified.
　本発明の有機ＥＬ素子の発光層に含有されるホスト化合物としては、室温（２５℃）におけるリン光発光のリン光量子収率が０．１未満の化合物が好ましい。さらに好ましくはリン光量子収率が０．０１未満である。また、発光層に含有される化合物の中で、その層中での体積比が５０％以上であることが好ましい。 As the host compound contained in the light emitting layer of the organic EL device of the present invention, a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) of less than 0.1 is preferable. More preferably, the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the volume ratio in the layer is 50% or more among the compounds contained in a light emitting layer.
　ホスト化合物としては、本発明で規定する上記条件を持たす化合物であれば特に制限はなく、公知のホスト化合物を単独で用いてもよく、又は複数種併用して用いてもよい。ホスト化合物を複数種用いることで、電荷の移動を調整することが可能であり、有機ＥＬ素子を高効率化することができる。また、後述する発光材料を複数種用いることで異なる発光を混ぜることが可能となり、これにより任意の発光色を得ることができる。 The host compound is not particularly limited as long as it is a compound having the above conditions defined in the present invention, and a known host compound may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. Moreover, it becomes possible to mix different light emission by using multiple types of luminescent material mentioned later, and can thereby obtain arbitrary luminescent colors.
　また、本発明に用いられるホスト化合物としては、本発明で規定する上記条件を持たす化合物であれば特に制限はなく、従来公知の低分子化合物でも、繰り返し単位を持つ高分子化合物でもよく、ビニル基やエポキシ基のような重合性基を有する低分子化合物（重合性発光ホスト）でもよいが、高分子材料を用いた場合、化合物が溶媒を取り込んで膨潤やゲル化等、溶媒が抜けにくいと思われる現象が起こりやすいので、これを防ぐために分子量は高くない方が好ましく、具体的には塗布時での分子量が２０００以下の材料を用いることが好ましく、塗布時の分子量１０００以下の材料を用いることより好ましく、更に好ましくは分子量が５００～１０００の範囲内にあるホスト化合物であり、特に好ましくは、分子量が５５０～８５０の範囲内にあるホスト化合物であり、最も好ましくは分子量が６００～８００の範囲内にあるホスト化合物である。 The host compound used in the present invention is not particularly limited as long as it is a compound having the above-mentioned conditions defined in the present invention, and may be a conventionally known low molecular compound or a high molecular compound having a repeating unit, and may be a vinyl group. Or a low molecular compound (polymerizable light-emitting host) having a polymerizable group such as an epoxy group, but when a high molecular weight material is used, the compound may take up the solvent and swell or gelate, and the solvent is unlikely to escape. In order to prevent this phenomenon, it is preferable that the molecular weight is not high. Specifically, it is preferable to use a material having a molecular weight of 2000 or less at the time of coating, and a material having a molecular weight of 1000 or less at the time of coating. More preferred is a host compound having a molecular weight in the range of 500 to 1000, and particularly preferred is a molecular weight of 550 to 850. A host compound in 囲内, most preferably a host compound having a molecular weight in the range of 600-800.
　公知のホスト化合物としては、正孔輸送能、電子輸送能を有しつつ、かつ発光の長波長化を防ぎ、なおかつ高Ｔｇ（ガラス転移温度）である化合物が好ましい。ここで、ガラス転移点（Ｔｇ）とは、ＤＳＣ（Ｄｉｆｆｅｒｅｎｔｉａｌ　Ｓｃａｎｎｉｎｇ　Ｃｏｌｏｒｉｍｅｔｒｙ：示差走査熱量法）を用いて、ＪＩＳ－Ｋ－７１２１に準拠した方法により求められる値である。 As the known host compound, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being increased in wavelength, and has a high Tg (glass transition temperature) is preferable. Here, the glass transition point (Tg) is a value obtained by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).
　公知のホスト化合物の具体例としては、以下の文献に記載されている化合物が挙げられる。例えば、特開２００１－２５７０７６号公報、同２００２－３０８８５５号公報、同２００１－３１３１７９号公報、同２００２－３１９４９１号公報、同２００１－３５７９７７号公報、同２００２－３３４７８６号公報、同２００２－８８６０号公報、同２００２－３３４７８７号公報、同２００２－１５８７１号公報、同２００２－３３４７８８号公報、同２００２－４３０５６号公報、同２００２－３３４７８９号公報、同２００２－７５６４５号公報、同２００２－３３８５７９号公報、同２００２－１０５４４５号公報、同２００２－３４３５６８号公報、同２００２－１４１１７３号公報、同２００２－３５２９５７号公報、同２００２－２０３６８３号公報、同２００２－３６３２２７号公報、同２００２－２３１４５３号公報、同２００３－３１６５号公報、同２００２－２３４８８８号公報、同２００３－２７０４８号公報、同２００２－２５５９３４号公報、同２００２－２６０８６１号公報、同２００２－２８０１８３号公報、同２００２－２９９０６０号公報、同２００２－３０２５１６号公報、同２００２－３０５０８３号公報、同２００２－３０５０８４号公報、同２００２－３０８８３７号公報、米国特許公開第２００３０１７５５５３号明細書、米国特許公開第２００６０２８０９６５号明細書、米国特許公開第２００５０１１２４０７号明細書、米国特許公開第２００９００１７３３０号明細書、米国特許公開第２００９００３０２０２号明細書、米国特許公開第２００５０２３８９１９号明細書、国際公開第２００１／０３９２３４号、国際公開第２００９／０２１１２６号、国際公開第２００８／０５６７４６号、国際公開第２００４／０９３２０７号、国際公開第２００５／０８９０２５号、国際公開第２００７／０６３７９６号、国際公開第２００７／０６３７５４号、国際公開第２００４／１０７８２２号、国際公開第２００５／０３０９００号、国際公開第２００６／１１４９６６号、国際公開第２００９／０８６０２８号、国際公開第２００９／００３８９８号、国際公開第２０１２／０２３９４７号、特開２００８－０７４９３９号公報、特開２００７－２５４２９７号公報、ＥＰ第２０３４５３８号明細書等、が挙げられ、本発明で規定する上記条件を持たす化合物を選択して用いることができる。 Specific examples of known host compounds include compounds described in the following documents. For example, Japanese Patent Application Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579 No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. 2002-302516, 2002-305083, 2002-305084, 2002-308837, US Patent Publication No. 20030175553, US Patent Publication No. 20060280965, United States Patent Publication No. 20050112407, U.S. Patent Publication No. 20090017330, U.S. Publication No. 20090030202, U.S. Patent Publication No. 20050238919, International Publication No. 2001/039234, Country International Publication No. 2009/021126, International Publication No. 2008/056746, International Publication No. 2004/093207, International Publication No. 2005/089025, International Publication No. 2007/063796, International Publication No. 2007/063754, International Publication No. 2004/107822, International Publication No. 2005/030900, International Publication No. 2006/114966, International Publication No. 2009/086028, International Publication No. 2009/003898, International Publication No. 2012/023947, Japanese Patent Application Laid-Open No. 2008-074939. No. 2007-254297, EP 2034538, and the like, and compounds having the above-mentioned conditions defined in the present invention can be selected and used.
　更には、本発明においては、ホスト化合物が、下記一般式（１）で示される化合物であることが好ましい。これは、下記一般式（１）で表されるホスト化合物は、縮環構造を有するため、キャリア輸送性が高く、また前記の広い三重項エネルギー（リン光の０－０バンド）を有する観点から好ましい。 Furthermore, in the present invention, the host compound is preferably a compound represented by the following general formula (1). This is because the host compound represented by the following general formula (1) has a condensed ring structure, and therefore has a high carrier transport property, and also has the broad triplet energy (0-0 band of phosphorescence). preferable.
Figure JPOXMLDOC01-appb-C000005
  
Figure JPOXMLDOC01-appb-C000005
  
　上記一般式（１）において、Ｘは、ＮＲ′、酸素原子、硫黄原子、ＣＲ′Ｒ″、又はＳｉＲ′Ｒ″を表す。ｙ１及びｙ２は、各々ＣＲ′又は窒素原子を表す。Ｒ′及びＲ″は、各々水素原子又は置換基を表す。Ａｒ１及びＡｒ２は、各々芳香環を表し、それぞれ同一でも異なっていても良い。ｎは０～４の整数を表す。本発明に係る一般式（１）で表されるホスト化合物としては、特に、カルバゾール誘導体であることが好ましい。 In the general formula (1), X represents NR ′, oxygen atom, sulfur atom, CR′R ″, or SiR′R ″. y 1 and y 2 each represent CR ′ or a nitrogen atom. R ′ and R ″ each represent a hydrogen atom or a substituent. Ar 1 and Ar 2 each represent an aromatic ring and may be the same or different. N represents an integer of 0 to 4. As the host compound represented by the general formula (1), a carbazole derivative is particularly preferable.
　一般式（１）におけるＸ、ｙ１及びｙ２において、Ｒ′及びＲ″で各々表される置換基としては、例えば、アルキル基（例えば、メチル基、エチル基、プロピル基、イソプロピル基、ｔ－ブチル基、ペンチル基、ヘキシル基、オクチル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基等）、シクロアルキル基（例えば、シクロペンチル基、シクロヘキシル基等）、アルケニル基（例えば、ビニル基、アリル基等）、アルキニル基（例えば、エチニル基、プロパルギル基等）、芳香族炭化水素環基（芳香族炭素環基、アリール基等ともいい、例えば、フェニル基、ｐ－クロロフェニル基、メシチル基、トリル基、キシリル基、ナフチル基、アントリル基、アズレニル基、アセナフテニル基、フルオレニル基、フェナントリル基、インデニル基、ピレニル基、ビフェニリル基等）、芳香族複素環基（例えば、ピリジル基、ピリミジニル基、フリル基、ピロリル基、イミダゾリル基、ベンゾイミダゾリル基、ピラゾリル基、ピラジニル基、トリアゾリル基（例えば、１，２，４－トリアゾール－１－イル基、１，２，３－トリアゾール－１－イル基等）、オキサゾリル基、ベンゾオキサゾリル基、チアゾリル基、イソオキサゾリル基、イソチアゾリル基、フラザニル基、チエニル基、キノリル基、ベンゾフリル基、ジベンゾフリル基、ベンゾチエニル基、ジベンゾチエニル基、インドリル基、カルバゾリル基、カルボリニル基、ジアザカルバゾリル基（前記カルボリニル基のカルボリン環を構成する炭素原子の一つが窒素原子で置き換わったものを示す）、キノキサリニル基、ピリダジニル基、トリアジニル基、キナゾリニル基、フタラジニル基等）、複素環基（例えば、ピロリジル基、イミダゾリジル基、モルホリル基、オキサゾリジル基等）、アルコキシ基（例えば、メトキシ基、エトキシ基、プロピルオキシ基、ペンチルオキシ基、ヘキシルオキシ基、オクチルオキシ基、ドデシルオキシ基等）、シクロアルコキシ基（例えば、シクロペンチルオキシ基、シクロヘキシルオキシ基等）、アリールオキシ基（例えば、フェノキシ基、ナフチルオキシ基等）、アルキルチオ基（例えば、メチルチオ基、エチルチオ基、プロピルチオ基、ペンチルチオ基、ヘキシルチオ基、オクチルチオ基、ドデシルチオ基等）、シクロアルキルチオ基（例えば、シクロペンチルチオ基、シクロヘキシルチオ基等）、アリールチオ基（例えば、フェニルチオ基、ナフチルチオ基等）、アルコキシカルボニル基（例えば、メチルオキシカルボニル基、エチルオキシカルボニル基、ブチルオキシカルボニル基、オクチルオキシカルボニル基、ドデシルオキシカルボニル基等）、アリールオキシカルボニル基（例えば、フェニルオキシカルボニル基、ナフチルオキシカルボニル基等）、スルファモイル基（例えば、アミノスルホニル基、メチルアミノスルホニル基、ジメチルアミノスルホニル基、ブチルアミノスルホニル基、ヘキシルアミノスルホニル基、シクロヘキシルアミノスルホニル基、オクチルアミノスルホニル基、ドデシルアミノスルホニル基、フェニルアミノスルホニル基、ナフチルアミノスルホニル基、２－ピリジルアミノスルホニル基等）、アシル基（例えば、アセチル基、エチルカルボニル基、プロピルカルボニル基、ペンチルカルボニル基、シクロヘキシルカルボニル基、オクチルカルボニル基、２－エチルヘキシルカルボニル基、ドデシルカルボニル基、フェニルカルボニル基、ナフチルカルボニル基、ピリジルカルボニル基等）、アシルオキシ基（例えば、アセチルオキシ基、エチルカルボニルオキシ基、ブチルカルボニルオキシ基、オクチルカルボニルオキシ基、ドデシルカルボニルオキシ基、フェニルカルボニルオキシ基等）、アミド基（例えば、メチルカルボニルアミノ基、エチルカルボニルアミノ基、ジメチルカルボニルアミノ基、プロピルカルボニルアミノ基、ペンチルカルボニルアミノ基、シクロヘキシルカルボニルアミノ基、２－エチルヘキシルカルボニルアミノ基、オクチルカルボニルアミノ基、ドデシルカルボニルアミノ基、フェニルカルボニルアミノ基、ナフチルカルボニルアミノ基等）、カルバモイル基（例えば、アミノカルボニル基、メチルアミノカルボニル基、ジメチルアミノカルボニル基、プロピルアミノカルボニル基、ペンチルアミノカルボニル基、シクロヘキシルアミノカルボニル基、オクチルアミノカルボニル基、２－エチルヘキシルアミノカルボニル基、ドデシルアミノカルボニル基、フェニルアミノカルボニル基、ナフチルアミノカルボニル基、２－ピリジルアミノカルボニル基等）、ウレイド基（例えば、メチルウレイド基、エチルウレイド基、ペンチルウレイド基、シクロヘキシルウレイド基、オクチルウレイド基、ドデシルウレイド基、フェニルウレイド基ナフチルウレイド基、２－ピリジルアミノウレイド基等）、スルフィニル基（例えば、メチルスルフィニル基、エチルスルフィニル基、ブチルスルフィニル基、シクロヘキシルスルフィニル基、２－エチルヘキシルスルフィニル基、ドデシルスルフィニル基、フェニルスルフィニル基、ナフチルスルフィニル基、２－ピリジルスルフィニル基等）、アルキルスルホニル基（例えば、メチルスルホニル基、エチルスルホニル基、ブチルスルホニル基、シクロヘキシルスルホニル基、２－エチルヘキシルスルホニル基、ドデシルスルホニル基等）、アリールスルホニル基又はヘテロアリールスルホニル基（例えば、フェニルスルホニル基、ナフチルスルホニル基、２－ピリジルスルホニル基等）、アミノ基（例えば、アミノ基、エチルアミノ基、ジメチルアミノ基、ブチルアミノ基、シクロペンチルアミノ基、２－エチルヘキシルアミノ基、ドデシルアミノ基、アニリノ基、ナフチルアミノ基、２－ピリジルアミノ基等）、ハロゲン原子（例えば、フッ素原子、塩素原子、臭素原子等）、フッ化炭化水素基（例えば、フルオロメチル基、トリフルオロメチル基、ペンタフルオロエチル基、ペンタフルオロフェニル基等）、シアノ基、ニトロ基、ヒドロキシ基、メルカプト基、シリル基（例えば、トリメチルシリル基、トリイソプロピルシリル基、トリフェニルシリル基、フェニルジエチルシリル基等）等が挙げられる。これらの置換基は上記の置換基によって更に置換されていてもよい。これらの置換基は複数が互いに結合して環を形成していてもよい。 In X, y 1 and y 2 in the general formula (1), examples of the substituent represented by R ′ and R ″ include an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, t -Butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (eg, vinyl group, allyl group) Group), alkynyl group (for example, ethynyl group, propargyl group, etc.), aromatic hydrocarbon ring group (aromatic carbocyclic group, aryl group, etc.), for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl Group, xylyl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl , Indenyl group, pyrenyl group, biphenylyl group, etc.), aromatic heterocyclic group (for example, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1 , 2,4-triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group Quinolyl group, benzofuryl group, dibenzofuryl group, benzothienyl group, dibenzothienyl group, indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (one of the carbon atoms constituting the carboline ring of the carbolinyl group is nitrogen (Represented by atoms replaced), quinoxalini Group, pyridazinyl group, triazinyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propyloxy) Group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.) Alkylthio groups (for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio groups (for example, cyclopentylthio group, cyclohexylthio group, etc.), arylthio Group (for example, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (for example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group ( For example, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylamino) Sulfonyl groups, dodecylaminosulfonyl groups, phenylaminosulfonyl groups, naphthylaminosulfonyl groups, 2-pyridylaminosulfonyl groups, etc.), acyl groups (eg Acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (For example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethyl group) Carbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octyl Rucarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group) Cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, Ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2 Pyridylaminoureido group, etc.), sulfinyl groups (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group) Etc.), alkylsulfonyl group (eg, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (eg, phenylsulfonyl) Group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (eg, amino group, ethylamino group, dimethylamino group, buty Amino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom etc.), fluorinated carbonization Hydrogen group (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group) , Triphenylsilyl group, phenyldiethylsilyl group, etc.). These substituents may be further substituted with the above substituents. A plurality of these substituents may be bonded to each other to form a ring.
　中でも、ＬＵＭＯのエネルギー準位が浅く、電子輸送性に優れる構造として、一般式（１）で表される化合物において、Ｘが、ＮＲ′又は酸素原子である化合物が好ましい。すなわち、(アザ)カルバゾール環又は（アザ）ジベンゾフラン環を有する化合物であることが好ましい。より好ましくは、より電子輸送性に優れる(アザ)カルバゾール環を有する化合物である。ここでＲ′としては、芳香族炭化水素基（芳香族炭素環基、アリール基等ともいい、例えば、フェニル基、ｐ－クロロフェニル基、メシチル基、トリル基、キシリル基、ナフチル基、アントリル基、アズレニル基、アセナフテニル基、フルオレニル基、フェナントリル基、インデニル基、ピレニル基、ビフェニリル基等）、又は芳香族複素環基（例えば、フリル基、チエニル基、ピリジル基、ピリダジニル基、ピリミジニル基、ピラジニル基、トリアジニル基、イミダゾリル基、ピラゾリル基、チアゾリル基、キナゾリニル基、フタラジニル基等）が特に好ましい。 Among them, as a structure having a low LUMO energy level and excellent electron transportability, a compound represented by the general formula (1) is preferably a compound in which X is NR ′ or an oxygen atom. That is, a compound having a (aza) carbazole ring or a (aza) dibenzofuran ring is preferable. More preferably, it is a compound having a (aza) carbazole ring which is more excellent in electron transport property. Here, R ′ is an aromatic hydrocarbon group (also called an aromatic carbocyclic group, aryl group, etc., for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, An azulenyl group, an acenaphthenyl group, a fluorenyl group, a phenanthryl group, an indenyl group, a pyrenyl group, a biphenylyl group, or an aromatic heterocyclic group (for example, a furyl group, a thienyl group, a pyridyl group, a pyridazinyl group, a pyrimidinyl group, a pyrazinyl group, Triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazinyl group and the like are particularly preferable.
　上記の芳香族炭化水素基及び芳香族複素環基は、各々一般式（１）のＸにおいて、Ｒ′及びＲ″で各々表される置換基を有してもよい。 The above aromatic hydrocarbon group and aromatic heterocyclic group may each have a substituent represented by R ′ and R ″ in X of the general formula (1).
　一般式（１）において、ｙ１及びｙ２で表される原子としては、ＣＲ′又は窒素原子が挙げられるが、より好ましくはＣＲ′である。このような化合物は正孔輸送性にも優れ、陽極・陰極から注入された正孔・電子を効率よく発光層内で再結合・発光させることができる。 In the general formula (1), examples of the atoms represented by y 1 and y 2 include CR ′ and nitrogen atom, and CR ′ is more preferable. Such a compound is excellent in hole transportability, and can efficiently recombine and emit holes and electrons injected from the anode and cathode in the light emitting layer.
　一般式（１）において、Ａｒ１及びＡｒ２により表される芳香環としては、芳香族炭化水素環又は芳香族複素環が挙げられる。また、該芳香環は単環でもよく、縮合環でもよく、更に未置換でも、一般式（１）のＸにおいて、Ｒ′及びＲ″で各々表される置換基を有してもよい。 In the general formula (1), examples of the aromatic ring represented by Ar 1 and Ar 2 include an aromatic hydrocarbon ring and an aromatic heterocyclic ring. The aromatic ring may be a single ring or a condensed ring, and may be unsubstituted or may have a substituent represented by R ′ and R ″ in X of the general formula (1).
　一般式（１）において、Ａｒ１及びＡｒ２により表される芳香族炭化水素環としては、例えば、ベンゼン環、ビフェニル環、ナフタレン環、アズレン環、アントラセン環、フェナントレン環、ピレン環、クリセン環、ナフタセン環、トリフェニレン環、ｏ－テルフェニル環、ｍ－テルフェニル環、ｐ－テルフェニル環、アセナフテン環、コロネン環、フルオレン環、フルオラントレン環、ナフタセン環、ペンタセン環、ペリレン環、ペンタフェン環、ピセン環、ピレン環、ピラントレン環、アンスラアントレン環等が挙げられる。 In the general formula (1), examples of the aromatic hydrocarbon ring represented by Ar 1 and Ar 2 include a benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, Naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, Examples include a picene ring, a pyrene ring, a pyranthrene ring, and an anthraanthrene ring.
　一般式（１）で表される部分構造において、Ａｒ１及びＡｒ２により表される芳香族複素環としては、例えば、フラン環、ジベンゾフラン環、チオフェン環、オキサゾール環、ピロール環、ピリジン環、ピリダジン環、ピリミジン環、ピラジン環、トリアジン環、ベンゾイミダゾール環、オキサジアゾール環、トリアゾール環、イミダゾール環、ピラゾール環、チアゾール環、インドール環、インダゾール環、ベンゾイミダゾール環、ベンゾチアゾール環、ベンゾオキサゾール環、キノキサリン環、キナゾリン環、シンノリン環、キノリン環、イソキノリン環、フタラジン環、ナフチリジン環、カルバゾール環、カルボリン環、ジアザカルバゾール環（カルボリン環を構成する炭化水素環の炭素原子の一つが更に窒素原子で置換されている環を示す）等が挙げられる。 In the partial structure represented by the general formula (1), examples of the aromatic heterocycle represented by Ar 1 and Ar 2 include a furan ring, a dibenzofuran ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, and a pyridazine. Ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, indazole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, Quinoxaline ring, quinazoline ring, cinnoline ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, carbazole ring, carboline ring, diazacarbazole ring (one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is a nitrogen atom) Has been replaced Shown) and the like.
　これらの環は、更に一般式（１）において、Ｒ′及びＲ″で各々表される置換基を有してもよい。 These rings may further have a substituent represented by R ′ and R ″ in the general formula (1).
　上記の中でも、一般式（１）において、Ａｒ１及びＡｒ２により表される芳香環として、好ましく用いられるのは、カルバゾール環、カルボリン環、ジベンゾフラン環、ベンゼン環であり、更に好ましく用いられるのは、カルバゾール環、カルボリン環、ベンゼン環であり、より好ましくは置換基を有するベンゼン環であり、特に好ましくは、カルバゾリル基を有するベンゼン環が挙げられる。 Among the above, in the general formula (1), the aromatic ring represented by Ar 1 and Ar 2 is preferably a carbazole ring, carboline ring, dibenzofuran ring, or benzene ring, and more preferably used. , A carbazole ring, a carboline ring, and a benzene ring, more preferably a benzene ring having a substituent, and particularly preferably a benzene ring having a carbazolyl group.
　また、一般式（１）において、Ａｒ１及びＡｒ２により表される芳香環としては、各々３環以上の縮合環が好ましい一態様であり、３環以上が縮合した芳香族炭化水素縮合環としては、具体的には、ナフタセン環、アントラセン環、テトラセン環、ペンタセン環、ヘキサセン環、フェナントレン環、ピレン環、ベンゾピレン環、ベンゾアズレン環、クリセン環、ベンゾクリセン環、アセナフテン環、アセナフチレン環、トリフェニレン環、コロネン環、ベンゾコロネン環、ヘキサベンゾコロネン環、フルオレン環、ベンゾフルオレン環、フルオランテン環、ペリレン環、ナフトペリレン環、ペンタベンゾペリレン環、ベンゾペリレン環、ペンタフェン環、ピセン環、ピラントレン環、コロネン環、ナフトコロネン環、オバレン環、アンスラアントレン環等が挙げられる。なお、これらの環は、更に上記の置換基を有していてもよい。 In the general formula (1), the aromatic rings represented by Ar 1 and Ar 2 are each preferably a condensed ring of three or more rings, and as an aromatic hydrocarbon condensed ring in which three or more rings are condensed. Specifically, naphthacene ring, anthracene ring, tetracene ring, pentacene ring, hexacene ring, phenanthrene ring, pyrene ring, benzopyrene ring, benzoazulene ring, chrysene ring, benzochrysene ring, acenaphthene ring, acenaphthylene ring, triphenylene ring, Coronene ring, benzocoronene ring, hexabenzocoronene ring, fluorene ring, benzofluorene ring, fluoranthene ring, perylene ring, naphthperylene ring, pentabenzoperylene ring, benzoperylene ring, pentaphen ring, picene ring, pyranthrene ring, coronene ring, naphthocoronene ring , Ovalene ring, Ansula Ntoren ring and the like. In addition, these rings may further have the above substituent.
　また、３環以上が縮合した芳香族複素環としては、具体的には、アクリジン環、ベンゾキノリン環、カルバゾール環、カルボリン環、フェナジン環、フェナントリジン環、フェナントロリン環、カルボリン環、サイクラジン環、キンドリン環、テペニジン環、キニンドリン環、トリフェノジチアジン環、トリフェノジオキサジン環、フェナントラジン環、アントラジン環、ペリミジン環、ジアザカルバゾール環（カルボリン環を構成する炭素原子の任意の一つが窒素原子で置き換わったものを表す）、フェナントロリン環、ジベンゾフラン環、ジベンゾチオフェン環、ナフトフラン環、ナフトチオフェン環、ベンゾジフラン環、ベンゾジチオフェン環、ナフトジフラン環、ナフトジチオフェン環、アントラフラン環、アントラジフラン環、アントラチオフェン環、アントラジチオフェン環、チアントレン環、フェノキサチイン環、チオファントレン環（ナフトチオフェン環）等が挙げられる。なお、これらの環は更に置換基を有していてもよい。 Specific examples of the aromatic heterocycle condensed with three or more rings include an acridine ring, a benzoquinoline ring, a carbazole ring, a carboline ring, a phenazine ring, a phenanthridine ring, a phenanthroline ring, a carboline ring, a cyclazine ring, Kindin ring, tepenidine ring, quinindrin ring, triphenodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, diazacarbazole ring (any one of the carbon atoms constituting the carboline ring is a nitrogen atom Phenanthroline ring, dibenzofuran ring, dibenzothiophene ring, naphthofuran ring, naphthothiophene ring, benzodifuran ring, benzodithiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, Emissions tiger thiophene ring, anthradithiophene ring, thianthrene ring, phenoxathiin ring, such as thio fan train ring (naphthothiophene ring). In addition, these rings may further have a substituent.
　また、一般式（１）において、ｎは０～４の整数を表すが、０～２であることが好ましく、特に、Ｘが、酸素原子又は硫黄原子である場合には、１～２であることが好ましい。 In the general formula (1), n represents an integer of 0 to 4, preferably 0 to 2, and particularly 1 to 2 when X is an oxygen atom or a sulfur atom. It is preferable.
　本発明においては、特に、ジベンゾフラン環とカルバゾール環をともに有するホスト化合物が好ましい。 In the present invention, a host compound having both a dibenzofuran ring and a carbazole ring is particularly preferable.
　本発明に係るホスト化合物として、前記一般式（１）で表される化合物が、下記一般式（２）で表される化合物であることが好ましい。すなわち、３位がフェニル基で置換されたカルバゾール環を有する化合物であることが好ましい。このような化合物は、特にキャリア輸送性に優れ、かつ量子ドットへのキャリア注入に優れる傾向があるためである。 As the host compound according to the present invention, the compound represented by the general formula (1) is preferably a compound represented by the following general formula (2). That is, a compound having a carbazole ring substituted at the 3-position with a phenyl group is preferable. This is because such a compound tends to be particularly excellent in carrier transportability and excellent in carrier injection into quantum dots.
Figure JPOXMLDOC01-appb-C000006
  
Figure JPOXMLDOC01-appb-C000006
  
　上記一般式（２）において、Ａｒ３～Ａｒ５は各々芳香環を表し、それぞれ同一でも異なっていても良い。ｎ１は０～４の整数を表し、ｎ２は０～５の整数を表す。 In the general formula (2), Ar 3 to Ar 5 each represents an aromatic ring, and may be the same or different. n1 represents an integer of 0 to 4, and n2 represents an integer of 0 to 5.
　Ａｒ３～Ａｒ５で表される芳香環は、前記一般式（１）においてＡｒ１及びＡｒ２により表される芳香環と同様のものを挙げることができる。 Examples of the aromatic ring represented by Ar 3 to Ar 5 include the same aromatic rings as those represented by Ar 1 and Ar 2 in the general formula (1).
　以下に、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４１４～４５９ｎｍ（２．７～３．０ｅＶ）の範囲内にある本発明に係るホスト化合物として、一般式（１）で表される化合物、一般式（２）で表される化合物及びその他の構造からなる化合物例を示すが、これらに限定されるものではない。 Hereinafter, as a host compound according to the present invention in which the emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum is in the range of 414 to 459 nm (2.7 to 3.0 eV), the general formula (1) Although the compound example consisting of the compound represented, the compound represented by General formula (2), and another structure is shown, it is not limited to these.
Figure JPOXMLDOC01-appb-C000007
  
Figure JPOXMLDOC01-appb-C000007
  
Figure JPOXMLDOC01-appb-C000008
  
Figure JPOXMLDOC01-appb-C000008
  
Figure JPOXMLDOC01-appb-C000009
  
Figure JPOXMLDOC01-appb-C000009
  
Figure JPOXMLDOC01-appb-C000010
  
Figure JPOXMLDOC01-appb-C000010
  
Figure JPOXMLDOC01-appb-C000011
  
Figure JPOXMLDOC01-appb-C000011
  
Figure JPOXMLDOC01-appb-C000012
  
Figure JPOXMLDOC01-appb-C000012
  
Figure JPOXMLDOC01-appb-C000013
  
Figure JPOXMLDOC01-appb-C000013
  
Figure JPOXMLDOC01-appb-C000014
  
Figure JPOXMLDOC01-appb-C000014
  
Figure JPOXMLDOC01-appb-C000015
  
Figure JPOXMLDOC01-appb-C000015
  
Figure JPOXMLDOC01-appb-C000016
  
Figure JPOXMLDOC01-appb-C000016
  
Figure JPOXMLDOC01-appb-C000017
  
Figure JPOXMLDOC01-appb-C000017
  
Figure JPOXMLDOC01-appb-C000018
  
Figure JPOXMLDOC01-appb-C000018
  
Figure JPOXMLDOC01-appb-C000019
  
Figure JPOXMLDOC01-appb-C000019
  
Figure JPOXMLDOC01-appb-C000020
  
Figure JPOXMLDOC01-appb-C000020
  
Figure JPOXMLDOC01-appb-C000021
  
Figure JPOXMLDOC01-appb-C000021
  
Figure JPOXMLDOC01-appb-C000022
  
Figure JPOXMLDOC01-appb-C000022
  
Figure JPOXMLDOC01-appb-C000023
  
Figure JPOXMLDOC01-appb-C000023
  
Figure JPOXMLDOC01-appb-C000024
  
Figure JPOXMLDOC01-appb-C000024
  
Figure JPOXMLDOC01-appb-C000025
  
Figure JPOXMLDOC01-appb-C000025
  
Figure JPOXMLDOC01-appb-C000026
  
Figure JPOXMLDOC01-appb-C000026
  
Figure JPOXMLDOC01-appb-C000027
  
Figure JPOXMLDOC01-appb-C000027
  
Figure JPOXMLDOC01-appb-C000028
  
Figure JPOXMLDOC01-appb-C000028
  
Figure JPOXMLDOC01-appb-C000029
  
Figure JPOXMLDOC01-appb-C000029
  
Figure JPOXMLDOC01-appb-C000030
  
Figure JPOXMLDOC01-appb-C000030
  
Figure JPOXMLDOC01-appb-C000031
  
Figure JPOXMLDOC01-appb-C000031
  
Figure JPOXMLDOC01-appb-C000032
  
Figure JPOXMLDOC01-appb-C000032
  
Figure JPOXMLDOC01-appb-C000033
  
Figure JPOXMLDOC01-appb-C000033
  
Figure JPOXMLDOC01-appb-C000034
  
Figure JPOXMLDOC01-appb-C000034
  
Figure JPOXMLDOC01-appb-C000035
  
Figure JPOXMLDOC01-appb-C000035
  
Figure JPOXMLDOC01-appb-C000036
  
Figure JPOXMLDOC01-appb-C000036
  
Figure JPOXMLDOC01-appb-C000037
  
Figure JPOXMLDOC01-appb-C000037
  
Figure JPOXMLDOC01-appb-C000038
  
Figure JPOXMLDOC01-appb-C000038
  
　（４．２）発光材料
　発光層に適用する発光材料としては、一般には、蛍光性化合物、リン光発光材料（リン光発光性化合物、リン光性化合物、リン光発光ドーパントともいう。）を用いられているが、本発明に係る発光層においては、発光材料として少なくともリン光発光性化合物を用いることを特徴とする。 (4.2) Light-Emitting Material As the light-emitting material applied to the light-emitting layer, generally, a fluorescent compound or a phosphorescent material (also referred to as a phosphorescent compound, a phosphorescent compound, or a phosphorescent dopant) is used. However, in the light emitting layer according to the present invention, at least a phosphorescent compound is used as the light emitting material.
　本発明において、リン光発光性化合物とは、励起三重項からの発光が観測される化合物であり、具体的には室温（２５℃）にてリン光発光する化合物であり、リン光量子収率が２５℃において０．０１以上の化合物であると定義されるが、好ましいリン光量子収率は０．１以上である。 In the present invention, the phosphorescent compound is a compound in which light emission from an excited triplet is observed, specifically a compound that emits phosphorescence at room temperature (25 ° C.), and has a phosphorescence quantum yield. Although defined as a compound of 0.01 or more at 25 ° C., a preferred phosphorescence quantum yield is 0.1 or more.
　上記リン光量子収率は、例えば、第４版実験化学講座７の分光IIの３９８頁（１９９２年版、丸善）に記載の方法により測定できる。溶液中でのリン光量子収率は、種々の溶媒を用いて測定できるが、本発明に係るリン光発光材料においては、任意の溶媒のいずれかにおいて上記リン光量子収率（０．０１以上）が達成されればよい。 The phosphorescence quantum yield can be measured, for example, by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of the Fourth Edition Experimental Chemistry Course 7. Although the phosphorescence quantum yield in a solution can be measured using various solvents, in the phosphorescent light emitting material according to the present invention, the phosphorescence quantum yield (0.01 or more) is obtained in any solvent. It only has to be achieved.
　リン光発光材料の発光原理としては二種挙げられ、一つはキャリアが輸送されるホスト化合物上でキャリアの再結合が起こってホスト化合物の励起状態が生成し、このエネルギーをリン光発光材料に移動させることでリン光発光材料からの発光を得るというエネルギー移動型、もう一つはリン光発光材料がキャリアトラップとなり、リン光発光材料上でキャリアの再結合が起こりリン光発光材料からの発光が得られるというキャリアトラップ型であるが、いずれの場合においても、リン光発光材料の励起状態のエネルギーは、ホスト化合物の励起状態のエネルギーよりも低いことが条件である。 There are two types of light emission principles of phosphorescent materials. One is the recombination of carriers on the host compound to which carriers are transported, generating an excited state of the host compound, and this energy is converted into the phosphorescent material. The energy transfer type that obtains light emission from the phosphorescent light emitting material by moving it, and the other is that the phosphorescent light emitting material becomes a carrier trap, and carrier recombination occurs on the phosphorescent light emitting material, and light emission from the phosphorescent light emitting material In any case, the excited state energy of the phosphorescent material is lower than the excited state energy of the host compound.
　リン光発光材料は、有機ＥＬ素子の発光層に使用される公知のものの中から適宜選択して用いることができるが、好ましくは元素の周期表で８～１０族の金属を含有する錯体系化合物であり、さらに好ましくはイリジウム化合物、オスミウム化合物、又は白金化合物（白金錯体系化合物）、希土類錯体であり、中でも最も好ましいのはイリジウム化合物である。 The phosphorescent light-emitting material can be appropriately selected from known materials used for the light-emitting layer of the organic EL element, but is preferably a complex compound containing a group 8-10 metal in the periodic table of elements. More preferred are iridium compounds, osmium compounds, platinum compounds (platinum complex compounds), and rare earth complexes, and most preferred are iridium compounds.
　また、本発明に係るリン光発光ドーパントとしては、リン光スペクトルにおける０－０遷移バンドに帰属する発光波長が、４９６～８２７ｎｍ（２．５～１．５ｅＶ）の範囲内にあるリン光発光ドーパントであることが好ましい。このような範囲の発光波長を有するリン光発光ドーパントと、本発明に係る４１３～４７７ｎｍに発光する量子ドット化合物とのスペクトルの組合せにより、演色性の高い白色照明を得ることができる。 In addition, as the phosphorescent dopant according to the present invention, the phosphorescent dopant in which the emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum is in the range of 496 to 827 nm (2.5 to 1.5 eV). It is preferable that White illumination with high color rendering can be obtained by combining the spectrum of the phosphorescent dopant having an emission wavelength in such a range and the quantum dot compound emitting light at 413 to 477 nm according to the present invention.
　本発明に係るリン光発光ドーパントの０－０遷移バンドに帰属する発光波長は、前記ホスト化合物の０－０遷移バンドに帰属する発光波長の測定に用いたのと同様の方法で求めることができる。 The emission wavelength attributed to the 0-0 transition band of the phosphorescent dopant according to the present invention can be determined by the same method used for the measurement of the emission wavelength attributed to the 0-0 transition band of the host compound. .
　本発明に係るリン光発光性化合物としては、下記一般式（３）で表されるリン光発光ドーパントが好ましい。 The phosphorescent compound according to the present invention is preferably a phosphorescent dopant represented by the following general formula (3).
Figure JPOXMLDOC01-appb-C000039
  
Figure JPOXMLDOC01-appb-C000039
  
　上記一般式（３）において、Ｒ１は置換基を表す。Ｚは５～７員環を形成するのに必要な非金属原子群を表す。ｎ１は０～５の整数を表す。Ｂ１～Ｂ５は各々炭素原子、窒素原子、酸素原子、又は硫黄原子を表し、少なくとも一つは窒素原子を表す。Ｍ１は元素周期表における８族～１０族の金属を表す。Ｘ１及びＸ２は各々炭素原子、窒素原子又は酸素原子を表し、Ｌ１はＸ１及びＸ２と共に２座の配位子を形成する原子群を表す。ｍ１は１、２、又は３の整数を表し、ｍ２は０、１、又は２の整数を表すが、ｍ１＋ｍ２は２又は３である。 In the general formula (3), R 1 represents a substituent. Z represents a nonmetallic atom group necessary for forming a 5- to 7-membered ring. n1 represents an integer of 0 to 5. B 1 to B 5 each represent a carbon atom, a nitrogen atom, an oxygen atom, or a sulfur atom, and at least one represents a nitrogen atom. M 1 represents a group 8 to group 10 metal in the periodic table. X 1 and X 2 each represent a carbon atom, a nitrogen atom or an oxygen atom, and L 1 represents an atomic group which forms a bidentate ligand together with X 1 and X 2 . m1 represents an integer of 1, 2, or 3, m2 represents an integer of 0, 1, or 2, and m1 + m2 is 2 or 3.
　本発明に係る一般式（３）で表されるリン光発光性化合物は、ＨＯＭＯが－５．１５～－３．５０ｅＶ、ＬＵＭＯが－１．２５～＋１．００ｅＶであり、好ましくはＨＯＭＯが－４．８０～－３．５０ｅＶ、ＬＵＭＯが－０．８０～＋１．００ｅＶである。 The phosphorescent compound represented by the general formula (3) according to the present invention has a HOMO of −5.15 to −3.50 eV, a LUMO of −1.25 to +1.00 eV, and preferably a HOMO of − 4.80 to −3.50 eV, and LUMO is −0.80 to +1.00 eV.
　一般式（３）で表されるリン光発光性化合物において、Ｒ１で表される置換基としては、例えば、アルキル基（例えば、メチル基、エチル基、プロピル基、イソプロピル基、ｔｅｒｔ－ブチル基、ペンチル基、ヘキシル基、オクチル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基等）、シクロアルキル基（例えば、シクロペンチル基、シクロヘキシル基等）、アルケニル基（例えば、ビニル基、アリル基等）、アルキニル基（例えば、エチニル基、プロパルギル基等）、芳香族炭化水素環基（芳香族炭素環基、アリール基等ともいい、例えば、フェニル基、ｐ－クロロフェニル基、メシチル基、トリル基、キシリル基、ナフチル基、アントリル基、アズレニル基、アセナフテニル基、フルオレニル基、フェナントリル基、インデニル基、ピレニル基、ビフェニリル基等）、芳香族複素環基（例えば、ピリジル基、ピリミジニル基、フリル基、ピロリル基、イミダゾリル基、ベンゾイミダゾリル基、ピラゾリル基、ピラジニル基、トリアゾリル基（例えば、１，２，４－トリアゾール－１－イル基、１，２，３－トリアゾール－１－イル基等）、オキサゾリル基、ベンゾオキサゾリル基、チアゾリル基、イソオキサゾリル基、イソチアゾリル基、フラザニル基、チエニル基、キノリル基、ベンゾフリル基、ジベンゾフリル基、ベンゾチエニル基、ジベンゾチエニル基、インドリル基、カルバゾリル基、カルボリニル基、ジアザカルバゾリル基（前記カルボリニル基のカルボリン環を構成する炭素原子の一つが窒素原子で置き換わったものを示す）、キノキサリニル基、ピリダジニル基、トリアジニル基、キナゾリニル基、フタラジニル基等）、複素環基（例えば、ピロリジル基、イミダゾリジル基、モルホリル基、オキサゾリジル基等）、アルコキシ基（例えば、メトキシ基、エトキシ基、プロピルオキシ基、ペンチルオキシ基、ヘキシルオキシ基、オクチルオキシ基、ドデシルオキシ基等）、シクロアルコキシ基（例えば、シクロペンチルオキシ基、シクロヘキシルオキシ基等）、アリールオキシ基（例えば、フェノキシ基、ナフチルオキシ基等）、アルキルチオ基（例えば、メチルチオ基、エチルチオ基、プロピルチオ基、ペンチルチオ基、ヘキシルチオ基、オクチルチオ基、ドデシルチオ基等）、シクロアルキルチオ基（例えば、シクロペンチルチオ基、シクロヘキシルチオ基等）、アリールチオ基（例えば、フェニルチオ基、ナフチルチオ基等）、アルコキシカルボニル基（例えば、メチルオキシカルボニル基、エチルオキシカルボニル基、ブチルオキシカルボニル基、オクチルオキシカルボニル基、ドデシルオキシカルボニル基等）、アリールオキシカルボニル基（例えば、フェニルオキシカルボニル基、ナフチルオキシカルボニル基等）、スルファモイル基（例えば、アミノスルホニル基、メチルアミノスルホニル基、ジメチルアミノスルホニル基、ブチルアミノスルホニル基、ヘキシルアミノスルホニル基、シクロヘキシルアミノスルホニル基、オクチルアミノスルホニル基、ドデシルアミノスルホニル基、フェニルアミノスルホニル基、ナフチルアミノスルホニル基、２－ピリジルアミノスルホニル基等）、アシル基（例えば、アセチル基、エチルカルボニル基、プロピルカルボニル基、ペンチルカルボニル基、シクロヘキシルカルボニル基、オクチルカルボニル基、２－エチルヘキシルカルボニル基、ドデシルカルボニル基、フェニルカルボニル基、ナフチルカルボニル基、ピリジルカルボニル基等）、アシルオキシ基（例えば、アセチルオキシ基、エチルカルボニルオキシ基、ブチルカルボニルオキシ基、オクチルカルボニルオキシ基、ドデシルカルボニルオキシ基、フェニルカルボニルオキシ基等）、アミド基（例えば、メチルカルボニルアミノ基、エチルカルボニルアミノ基、ジメチルカルボニルアミノ基、プロピルカルボニルアミノ基、ペンチルカルボニルアミノ基、シクロヘキシルカルボニルアミノ基、２－エチルヘキシルカルボニルアミノ基、オクチルカルボニルアミノ基、ドデシルカルボニルアミノ基、フェニルカルボニルアミノ基、ナフチルカルボニルアミノ基等）、カルバモイル基（例えば、アミノカルボニル基、メチルアミノカルボニル基、ジメチルアミノカルボニル基、プロピルアミノカルボニル基、ペンチルアミノカルボニル基、シクロヘキシルアミノカルボニル基、オクチルアミノカルボニル基、２－エチルヘキシルアミノカルボニル基、ドデシルアミノカルボニル基、フェニルアミノカルボニル基、ナフチルアミノカルボニル基、２－ピリジルアミノカルボニル基等）、ウレイド基（例えば、メチルウレイド基、エチルウレイド基、ペンチルウレイド基、シクロヘキシルウレイド基、オクチルウレイド基、ドデシルウレイド基、フェニルウレイド基ナフチルウレイド基、２－ピリジルアミノウレイド基等）、スルフィニル基（例えば、メチルスルフィニル基、エチルスルフィニル基、ブチルスルフィニル基、シクロヘキシルスルフィニル基、２－エチルヘキシルスルフィニル基、ドデシルスルフィニル基、フェニルスルフィニル基、ナフチルスルフィニル基、２－ピリジルスルフィニル基等）、アルキルスルホニル基（例えば、メチルスルホニル基、エチルスルホニル基、ブチルスルホニル基、シクロヘキシルスルホニル基、２－エチルヘキシルスルホニル基、ドデシルスルホニル基等）、アリールスルホニル基又はヘテロアリールスルホニル基（例えば、フェニルスルホニル基、ナフチルスルホニル基、２－ピリジルスルホニル基等）、アミノ基（例えば、アミノ基、エチルアミノ基、ジメチルアミノ基、ブチルアミノ基、シクロペンチルアミノ基、２－エチルヘキシルアミノ基、ドデシルアミノ基、アニリノ基、ナフチルアミノ基、２－ピリジルアミノ基等）、シアノ基、ニトロ基、ヒドロキシ基、メルカプト基、シリル基（例えば、トリメチルシリル基、トリイソプロピルシリル基、トリフェニルシリル基、フェニルジエチルシリル基等）等が挙げられる。これらの置換基のうち、好ましいものはアルキル基又はアリール基である。 In the phosphorescent compound represented by the general formula (3), examples of the substituent represented by R 1 include an alkyl group (eg, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group). Pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl group, allyl group, etc.) Alkynyl group (eg, ethynyl group, propargyl group, etc.), aromatic hydrocarbon ring group (also called aromatic carbocyclic group, aryl group, etc.), for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl Group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, Indenyl group, pyrenyl group, biphenylyl group, etc.), aromatic heterocyclic group (for example, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1, 2,4-triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group, A quinolyl group, a benzofuryl group, a dibenzofuryl group, a benzothienyl group, a dibenzothienyl group, an indolyl group, a carbazolyl group, a carbolinyl group, a diazacarbazolyl group (one of the carbon atoms constituting the carboline ring of the carbolinyl group is a nitrogen atom) Quinoxalinyl) , Pyridazinyl group, triazinyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propyloxy group, Pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio Groups (for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio groups (for example, cyclopentylthio group, cyclohexylthio group, etc.), arylthio (Eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, , Phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group) Group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, Acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group ( For example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonyl) Amino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octyl Sulfonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, Cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethyl) Ureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2- Lysylaminoureido group, etc.), sulfinyl groups (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group) Group), alkylsulfonyl group (eg methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group etc.), arylsulfonyl group or heteroarylsulfonyl group (eg phenyl Sulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butyryl) Mino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group) , Triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.). Of these substituents, preferred are an alkyl group and an aryl group.
　Ｚは、５～７員環を形成するのに必要な非金属原子群を表す。Ｚにより形成される５～７員環としては、例えば、ベンゼン環、ナフタレン環、ピリジン環、ピリミジン環、ピロール環、チオフェン環、ピラゾール環、イミダゾール環、オキサゾール環及びチアゾール環等が挙げられる。これらのうちで好ましいものは、ベンゼン環である。 Z represents a nonmetallic atom group necessary for forming a 5- to 7-membered ring. Examples of the 5- to 7-membered ring formed by Z include a benzene ring, naphthalene ring, pyridine ring, pyrimidine ring, pyrrole ring, thiophene ring, pyrazole ring, imidazole ring, oxazole ring and thiazole ring. Of these, a benzene ring is preferred.
　Ｂ１～Ｂ５は、各々炭素原子、窒素原子、酸素原子もしくは硫黄原子を表し、少なくとも一つは窒素原子を表す。これら５つの原子により形成される芳香族含窒素複素環としては単環が好ましい。例えば、ピロール環、ピラゾール環、イミダゾール環、トリアゾール環、テトラゾール環、オキサゾール環、イソオキサゾール環、チアゾール環、イソチアゾール環、オキサジアゾール環及びチアジアゾー環ル等が挙げられる。これらのうちで好ましいものは、ピラゾール環、イミダゾール環であり、特に好ましくはＢ２及びＢ５が各々窒素原子であるイミダゾール環である。これらの環は上記の置換基によって更に置換されていてもよい。置換基として好ましいものはアルキル基及びアリール基であり、更に好ましくはアリール基である。 B 1 to B 5 each represent a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom, and at least one represents a nitrogen atom. The aromatic nitrogen-containing heterocycle formed by these five atoms is preferably a monocycle. Examples include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, oxadiazole ring, and thiadiazole ring. Among these, a pyrazole ring and an imidazole ring are preferable, and an imidazole ring in which B 2 and B 5 are each a nitrogen atom is particularly preferable. These rings may be further substituted with the above substituents. Preferred as the substituent are an alkyl group and an aryl group, and more preferably an aryl group.
　Ｌ１は、Ｘ１及びＸ２と共に２座の配位子を形成する原子群を表す。Ｘ１－Ｌ１－Ｘ２で表される２座の配位子の具体例としては、例えば、置換又は無置換のフェニルピリジン、フェニルピラゾール、フェニルイミダゾール、フェニルトリアゾール、フェニルテトラゾール、ピラザボル、ピコリン酸及びアセチルアセトン等が挙げられる。これらの基は上記の置換基によって更に置換されていてもよい。 L 1 represents an atomic group that forms a bidentate ligand together with X 1 and X 2 . Specific examples of the bidentate ligand represented by X 1 -L 1 -X 2 include, for example, substituted or unsubstituted phenylpyridine, phenylpyrazole, phenylimidazole, phenyltriazole, phenyltetrazole, pyrazabol, picolinic acid And acetylacetone. These groups may be further substituted with the above substituents.
　ｍ１は、１、２又は３の整数を表し、ｍ２は０、１又は２の整数を表すが、ｍ１＋ｍ２は２又は３である。中でも、ｍ２は０である場合が好ましい。Ｍ１で表される金属としては、元素周期表の８～１０族の遷移金属元素（単に遷移金属ともいう）が用いられるが、中でもイリジウム、白金が好ましく、更に好ましくはイリジウムである。 m1 represents an integer of 1, 2 or 3, m2 represents an integer of 0, 1 or 2, and m1 + m2 is 2 or 3. Especially, the case where m2 is 0 is preferable. As the metal represented by M 1 , a transition metal element belonging to Group 8 to 10 of the periodic table (also simply referred to as a transition metal) is used, among which iridium and platinum are preferable, and iridium is more preferable.
　以下に、本発明に使用できる公知のリン光ドーパントの具体例が記載されている文献等を示すが、これら各文献中に記載されている化合物の中でもリン光スペクトルにおける０－０遷移バンドに帰属する発光波長が、４９６～８２７ｎｍ（２．５～１．５ｅＶ）の範囲内にあるリン光発光性化合物がより好ましい。 The following is a literature in which specific examples of known phosphorescent dopants that can be used in the present invention are described. Among these compounds, among these compounds, they belong to the 0-0 transition band in the phosphorescence spectrum. A phosphorescent compound having an emission wavelength in the range of 496 to 827 nm (2.5 to 1.5 eV) is more preferable.
　本発明に使用できる公知のリン光ドーパントの具体例としては、以下の文献に記載されている化合物等が挙げられる。 Specific examples of known phosphorescent dopants that can be used in the present invention include compounds described in the following documents.
　例えば、Ｎａｔｕｒｅ　３９５，１５１（１９９８）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７８，１６２２（２００１）、Ａｄｖ．Ｍａｔｅｒ．１９，７３９（２００７）、Ｃｈｅｒｎ．Ｍａｔｅｒ．１７，３５３２（２００５）、Ａｄｖ．Ｍａｔｅｒ．１７，１０５９（２００５）、Ｉｎｏｒｇ．Ｃｈｅｒｎ．４０，１７０４（２００１）、Ｃｈｅｒｎ．Ｍａｔｅｒ．１６，２４８０（２００４）、Ａｄｖ．Ｍａｔｅｒ．１６，２００３（２００４）、Ａｎｇｅｗ．Ｃｈｅｒｎ．ｌｎｔ．Ｅｄ．２００６，４５，７８００、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．８６，１５３５０５（２００５）、Ｃｈｅｒｎ．Ｌｅｔｔ．３４，５９２（２００５）、Ｃｈｅｒｎ．Ｃｏｍｍｕｎ．２９０６（２００５）、Ｉｎｏｒｇ．Ｃｈｅｒｎ．４２，１２４８（２００３）、Ａｎｇｅｗ．Ｃｈｅｒｎ．ｌｎｔ．Ｅｄ．４７，１（２００８）、Ｃｈｅｒｎ．Ｍａｔｅｒ．１８，５１１９（２００６）、Ｉｎｏｒｇ．Ｃｈｅｒｎ．４６，４３０８（２００７）、Ｏｒｇａｎｏｍｅｔａｌｌｉｃｓ２３，３７４５（２００４）、Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．７４，１３６１（１９９９）等の文献が挙げられる。 For example, Nature 395, 151 (1998), Appl. Phys. Lett. 78, 1622 (2001), Adv. Mater. 19, 739 (2007), Chern. Mater. 17, 3532 (2005), Adv. Mater. 17, 1059 (2005), Inorg. Chern. 40, 1704 (2001), Chern. Mater. 16, 2480 (2004), Adv. Mater. 16, 2003 (2004), Angew. Chern. lnt. Ed. 2006, 45, 7800, Appl. Phys. Lett. 86, 153505 (2005), Chern. Lett. 34, 592 (2005), Chern. Commun. 2906 (2005), Inorg. Chern. 42, 1248 (2003), Angew. Chern. lnt. Ed. 47, 1 (2008), Chern. Mater. 18, 5119 (2006), Inorg. Chern. 46, 4308 (2007), Organometallics 23, 3745 (2004), Appl. Phys. Lett. 74, 1361 (1999).
　また、国際公開第２００９／１００９９１号、国際公開第２００８／１０１８４２号、国際公開第２００３／０４０２５７号、米国特許公開第２００６８３５４６９号明細書、米国特許公開第２００６０２０２１９４号明細書、米国特許公開第２００７００８７３２１号明細書、米国特許公開第２００５０２４４６７３号明細書、国際公開第２００９／０５０２９０号、国際公開第２００２／０１５６４５号、国際公開第２００９／０００６７３号、米国特許公開第２００２００３４６５６号明細書、米国特許第７３３２２３２号明細書、米国特許公開第２００９０１０８７３７号明細書、米国特許公開第２００９００３９７７６号明細書、米国特許第６９２１９１５号明細書、米国特許第６６８７２６６号明細書、米国特許公開第２００７０１９０３５９号明細書、米国特許公開第２００６０００８６７０号明細書、米国特許公開第２００９０１６５８４６号明細書、米国特許公開第２００８００１５３５５号明細書、米国特許第７２５０２２６号明細書、米国特許第７３９６５９８号明細書、米国特許公開第２００６０２６３６３５号明細書、米国特許公開第２００３０１３８６５７号明細書、米国特許公開第２００３０１５２８０２号明細書、米国特許第７０９０９２８号明細書、国際公開第２００２／００２７１４号、国際公開第２００６／００９０２４号、国際公開第２００６／０５６４１８号、国際公開第２００５／０１９３７３号、国際公開第２００５／１２３８７３号、国際公開第２００５／１２３８７３号、国際公開第２００７／００４３８０号、国際公開第２００６／０８２７４２号、米国特許公開第２００６０２５１９２３号明細書、米国特許公開第２００５０２６０４４１号明細書、米国特許第７３９３５９９号明細書、米国特許第７５３４５０５号明細書、米国特許第７４４５８５５号明細書、米国特許公開第２００７０１９０３５９号明細書、米国特許公開第２００８０２９７０３３号明細書、米国特許第７３３８７２２号明細書、米国特許公開第２００２０１３４９８４号明細書、米国特許第７２７９７０４号明細書、米国特許公開第２００６０９８１２０号明細書、米国特許公開第２００６１０３８７４号明細書、国際公開第２００５／０７６３８０号、国際公開第２０１０／０３２６６３号、国際公開第第２００８／１４０１１５号、国際公開第２００７／０５２４３１号、国際公開第２０１１／１３４０１３号、国際公開第２０１１／１５７３３９号、国際公開第２０１０／０８６０８９号、国際公開第２００９／１１３６４６号、国際公開第２０１２／０２０３２７号、国際公開第２０１１／０５１４０４号、国際公開第２０１１／００４６３９号、国際公開第２０１１／０７３１４９号、特開２０１２－０６９７３７号公報、特開２０１２－１９５５５４号公報、特開２００９－１１４０８６号公報、特開２００３－８１９８８号公報、特開２００２－３０２６７１号公報、特開２００２－３６３５５２号公報等の特許文献が挙げられる。 In addition, International Publication No. 2009/100991, International Publication No. 2008/101842, International Publication No. 2003/040257, US Patent Publication No. 2006006835469, US Patent Publication No. 2006060202194, US Patent Publication No. 20070087321. Specification, US Patent Publication No. 20050246673, International Publication No. 2009/050290, International Publication No. 2002/015645, International Publication No. 2009/000673, US Patent Publication No. 20020034656, and US Pat. No. 7,332,232 Specification, US Patent Publication No. 20090108737, US Patent Publication No. 20090039776, US Patent No. 6921915, US Patent No. 6,687,266, US Patent Publication No. 200 No. 0190359, U.S. Patent Publication No. 2006086070, U.S. Pat. Publication No. 20090165846, U.S. Patent Publication No. 20080015355, U.S. Pat. No. 7,250,226, U.S. Pat. No. 7,396,598, U.S. Pat. Publication No. 20060263635, United States Patent Publication No. 20030138657, United States Patent Publication No. 2003015152802, United States Patent No. 7090928, International Publication No. 2002/002714, International Publication No. 2006/009024, International Publication No. Public Publication No. 2006/056418, International Publication No. 2005/019373, International Publication No. 2005/123873, International Publication No. 2005/123873, International Publication No. 2007/004380, International Publication No. 006/082742, U.S. Patent Publication No. 20060251923, U.S. Patent Publication No. 20050260441, U.S. Pat. No. 7,393,599, U.S. Pat. No. 7,534,505, U.S. Pat. No. 7,445,855, U.S. Pat. No. 20070190359, U.S. Patent Publication No. 20080297033, U.S. Pat. No. 7,338,722, U.S. Patent Publication No. 200201334984, U.S. Pat. No. 7,279,704, U.S. Pat. Publication No. 2006098120, U.S. Pat. Patent Publication No. 2006103874, International Publication No. 2005/076380, International Publication No. 2010/032663, International Publication No. 2008/140115, International Publication No. 2007/052431, International Publication 2011/134013, international publication 2011/157339, international publication 2010/088609, international publication 2009/113646, international publication 2012/020327, international publication 2011/051404, international publication 2011 / 004639, WO 2011/073149, JP 2012-069737, JP 2012-195554, JP 2009-114086, JP 2003-81988, JP 2002-302671. Patent documents such as Japanese Patent Laid-Open No. 2002-363552, and the like.
　中でも、好ましいリン光ドーパントとしてはＩｒを中心金属に有する有機金属錯体が挙げられる。さらに好ましくは、金属－炭素結合、金属－窒素結合、金属－酸素結合、金属－硫黄結合の少なくとも１つの配位様式を含む錯体が好ましい。 Among these, a preferable phosphorescent dopant includes an organometallic complex having Ir as a central metal. More preferably, a complex containing at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, and a metal-sulfur bond is preferable.
　（４．３）量子ドット
　本発明においては、本発明に係る発光層が、発光波長が４１３～４７７ｎｍの範囲内、すなわち青色領域に発光する量子ドットを含有することを特徴とする。より好ましくは、４４０～４７０ｎｍの範囲内。更に好ましくは４４５～４６５ｎｍの範囲内、特に好ましくは４５０～４６０ｎｍの範囲内で発光する量子ドットである。 (4.3) Quantum Dots The present invention is characterized in that the light emitting layer according to the present invention contains quantum dots that emit light in a light emission wavelength range of 413 to 477 nm, that is, in a blue region. More preferably, it is in the range of 440 to 470 nm. More preferably, the quantum dot emits light within a range of 445 to 465 nm, particularly preferably within a range of 450 to 460 nm.
　すなわち、図１に示すように、量子ドット１１は、発光層５に含有されていてもよいし、あるいは、発光層５と発光層５に隣接する層（例えば、正孔輸送層４あるいは電子輸送層６）との界面に存在していても良い。図２では、発光層５と発光層５に隣接する電子輸送層６との界面に、量子ドット１１が存在している例を示してある。本発明においては、特には、図１に示すように、量子ドット１１が、少なくとも発光層５に存在している態様が好ましい。 That is, as shown in FIG. 1, the quantum dots 11 may be contained in the light emitting layer 5, or the light emitting layer 5 and a layer adjacent to the light emitting layer 5 (for example, the hole transport layer 4 or the electron transport). It may be present at the interface with layer 6). FIG. 2 shows an example in which quantum dots 11 are present at the interface between the light emitting layer 5 and the electron transport layer 6 adjacent to the light emitting layer 5. In the present invention, in particular, as shown in FIG. 1, a mode in which the quantum dots 11 are present at least in the light emitting layer 5 is preferable.
　本発明に係る量子ドットとは、半導体材料の結晶で構成され、量子閉じ込め効果を有する所定の大きさを有する粒子をいい、その粒子径が数ｎｍ～数十ｎｍ程度の微粒子であり、下記に示す量子ドット効果が得られるものをいう。 The quantum dot according to the present invention refers to a particle having a predetermined size that is composed of a crystal of a semiconductor material and has a quantum confinement effect, and is a fine particle having a particle diameter of several nanometers to several tens of nanometers. The quantum dot effect shown is obtained.
　本発明に係る量子ドット（微粒子）の粒子径としては、具体的には１～２０ｎｍの範囲内であることが好ましく、更に好ましくは１～１０ｎｍの範囲内である。 The particle diameter of the quantum dots (fine particles) according to the present invention is specifically preferably in the range of 1 to 20 nm, more preferably in the range of 1 to 10 nm.
　このような量子ドットのエネルギー準位Ｅは、一般に、プランク定数を「ｈ」と、電子の有効質量を「ｍ」と、微粒子の半径を「Ｒ」としたとき、下式（Ｉ）で表される。 The energy level E of such a quantum dot is generally expressed by the following formula (I) when the Planck constant is “h”, the effective mass of the electron is “m”, and the radius of the fine particle is “R”. Is done.
　式（Ｉ）
　　　Ｅ∝ｈ２／ｍＲ２
　式（Ｉ）で示されるように、量子ドットのバンドギャップは、「Ｒ－２」に比例して大きくなり、いわゆる、量子ドット効果が得られる。このように、量子ドットの粒子径を制御、規定することによって、量子ドットのバンドギャップ値を制御することができる。すなわち、微粒子の粒子径を制御、規定することにより、通常の原子には無い多様性を持たせることができる。そのため、光によって励起させたり、量子ドットを含む有機ＥＬ素子に対して電圧をかけることで、量子ドットに電子とホールを閉じ込めて再結合させたりすることで電気エネルギーを所望の波長の光に変換して出射させることができる。本発明では、このような発光性の量子ドット材料を、本発明に係る量子ドットと定義する。 Formula (I)
E∝h 2 / mR 2
As shown by the formula (I), the band gap of the quantum dot increases in proportion to “R −2 ”, and a so-called quantum dot effect is obtained. Thus, the band gap value of a quantum dot can be controlled by controlling and defining the particle diameter of the quantum dot. That is, by controlling and defining the particle diameter of the fine particles, it is possible to provide diversity not found in ordinary atoms. For this reason, electrical energy can be converted into light of the desired wavelength by exciting electrons with light or applying voltage to organic EL elements that contain quantum dots to confine electrons and holes in the quantum dots and recombine them. Can be emitted. In the present invention, such a luminescent quantum dot material is defined as a quantum dot according to the present invention.
　量子ドットの平均粒子径は、上述したように、１ｎｍ～数十ｎｍ程度であるが、白色発光の発光材料の１つとして用いる場合、目的とする発光色に対応する平均粒子径に設定する。例えば、赤発光を得たい場合には、量子ドットの平均粒子径としては３．０～２０ｎｍの範囲内に設定することが好ましく、緑発光を得たい場合には、量子ドットの平均粒子径を１．５～１０ｎｍの範囲内に設定することが好ましく、青色発光を得たい場合には、量子ドットの平均粒子径を１．０～３．０ｎｍの範囲内に設定することが好ましい。ただしこれらの粒径は発光に関わるコア部分の素材によってもある程度異なるし、後述するような非発光性のシェル部等を有するような場合にはこれらの部分の膜厚が増加するため、必ずしも測定される粒径が上記の粒径となるわけではない。これらを含んだトータルの粒径としては１～２０ｎｍの範囲であることが好ましい。より好ましくは５～１７ｎｍ、さらに好ましくは１０～１５ｎｍの範囲の粒径のものである。 The average particle diameter of the quantum dots is about 1 nm to several tens of nm as described above, but when used as one of white light emitting materials, it is set to an average particle diameter corresponding to the target luminescent color. For example, when it is desired to obtain red light emission, the average particle diameter of the quantum dots is preferably set within a range of 3.0 to 20 nm. When green light emission is desired to be obtained, the average particle diameter of the quantum dots is set to It is preferable to set within the range of 1.5 to 10 nm, and when it is desired to obtain blue light emission, it is preferable to set the average particle diameter of the quantum dots within the range of 1.0 to 3.0 nm. However, these particle sizes vary to some extent depending on the material of the core part involved in light emission, and in the case of having a non-light emitting shell part as described later, the film thickness of these parts increases. The particle size to be produced is not the above particle size. The total particle size including these is preferably in the range of 1 to 20 nm. More preferably, the particle diameter is in the range of 5 to 17 nm, and more preferably 10 to 15 nm.
　量子ドットの平均粒子径の測定方法としては、公知の方法を用いることができる。例えば、透過型電子顕微鏡（ＴＥＭ）により量子ドットの粒子観察を行い、そこから粒子径分布の数平均粒子径として求める方法や、電子間力顕微鏡（ＡＦＭ）を用いて平均粒子径を求める方法、動的光散乱法による粒径測定装置、例えば、Ｍａｌｖｅｒｎ社製、「ＺＥＴＡＳＩＺＥＲＮａｎｏ　Ｓｅｒｉｅｓ　Ｎａｎｏ－ＺＳを用いて測定することができる。その他にも、Ｘ線小角散乱法により得られたスペクトルから量子ドットの粒子径分布シミュレーション計算を用いて粒子径分布を導出する方法などが挙げられるが、本発明においては、電子間力顕微鏡（ＡＦＭ）を用いて平均粒子径を求める方法が好ましい。 A known method can be used as a method for measuring the average particle diameter of the quantum dots. For example, a quantum dot particle observation is performed with a transmission electron microscope (TEM), and a method for obtaining the number average particle size of the particle size distribution therefrom, or a method for obtaining an average particle size using an electron force microscope (AFM), A particle size measuring apparatus using a dynamic light scattering method, for example, “ZETASIZER Nanos Nano-ZS, manufactured by Malvern, Inc. can also be measured. In addition, quantum dots can be obtained from spectra obtained by the X-ray small angle scattering method. A method of deriving a particle size distribution using particle size distribution simulation calculation and the like can be mentioned. In the present invention, a method of obtaining an average particle size using an electron force microscope (AFM) is preferable.
　また、本発明に係る量子ドットにおいては、アスペクト比（長軸径／短軸径）の値が、１．０～２．０の範囲内であることが好ましく、より好ましくは１．１～１．７の範囲内である。本発明に係る量子ドットに係るアスペクト比（長軸径／短軸径）についても、例えば、電子間力顕微鏡（ＡＦＭ）を用いて、長軸径及び短軸径を測定して求めることができる。なお測定する個体数としては、３００個以上であることが好ましい。 In the quantum dot according to the present invention, the aspect ratio (major axis diameter / minor axis diameter) is preferably in the range of 1.0 to 2.0, more preferably 1.1 to 1. Within the range of .7. The aspect ratio (major axis diameter / minor axis diameter) related to the quantum dots according to the present invention can also be determined by measuring the major axis diameter and the minor axis diameter using, for example, an electron force microscope (AFM). . The number of individuals to be measured is preferably 300 or more.
　量子ドットの添加量は、添加する層の全構成物質を１００質量部％としたとき、０．０１～５０質量％の範囲内であることが好ましく、０．０５～２５質量％の範囲内であることがより好ましく、０．１～２０質量％の範囲内であることが最も好ましい。添加量が０．０１質量％以上であれば、十分な輝度効率、演色性の良い白色発光を得ることができ、５０質量％以下であれば、適度な量子ドット粒子間距離を維持でき、量子サイズ効果を十分に発揮させることができる。 The addition amount of the quantum dots is preferably in the range of 0.01 to 50% by mass, and in the range of 0.05 to 25% by mass, when the total constituent materials of the layer to be added are 100% by mass. More preferably, it is most preferably in the range of 0.1 to 20% by mass. If the addition amount is 0.01% by mass or more, white light emission with sufficient luminance efficiency and good color rendering can be obtained, and if it is 50% by mass or less, an appropriate distance between quantum dot particles can be maintained. The size effect can be exhibited sufficiently.
　また、前述したリン光発光性化合物は、その励起寿命がミリ秒オーダーもしくはマイクロ秒オーダーと比較的長いために、層内での濃度が高すぎると励起子のエネルギーが振動緩和して消失するいわゆる濃度消光の問題が生じる。しかし、本発明に係る量子ドットを発光層もしくはその隣接層との界面に存在させることにより、量子ドット及びリン光発光性化合物そのものの発光が得られるだけに留まらず、詳細は不明だが量子ドットによる層全体の形状の変化や量子ドットの表面エネルギーによるリン光発光性化合物の分散性向上によるものと推測されるリン光発光性化合物の発光効率の向上効果が得られる。 In addition, since the above-described phosphorescent compound has a relatively long excitation lifetime of the order of milliseconds or microseconds, when the concentration in the layer is too high, the exciton energy relaxes and disappears. The problem of concentration quenching occurs. However, by allowing the quantum dots according to the present invention to exist at the interface with the light emitting layer or its adjacent layer, not only the light emission of the quantum dots and the phosphorescent compound itself can be obtained, but the details are unknown but the quantum dots The effect of improving the luminous efficiency of the phosphorescent compound, which is presumed to be due to the change in the shape of the entire layer and the improved dispersibility of the phosphorescent compound due to the surface energy of the quantum dots, can be obtained.
　量子ドットの構成材料としては、例えば、炭素、ケイ素、ゲルマニウム、錫等の周期表第１４族元素の単体、リン（黒リン）等の周期表第１５族元素の単体、セレン、テルル等の周期表第１６族元素の単体、炭化ケイ素（ＳｉＣ）等の複数の周期表第１４族元素からなる化合物、酸化錫（IV）（ＳｎＯ２）、硫化錫（II，IV）（Ｓｎ（II）Ｓｎ（IV）Ｓ３）、硫化錫（IV）（ＳｎＳ２）、硫化錫（II）（ＳｎＳ）、セレン化錫（II）（ＳｎＳｅ）、テルル化錫（II）（ＳｎＴｅ）、硫化鉛（II）（ＰｂＳ）、セレン化鉛（II）（ＰｂＳｅ）、テルル化鉛（II）（ＰｂＴｅ）等の周期表第１４族元素と周期表第１６族元素との化合物、窒化ホウ素（ＢＮ）、リン化ホウ素（ＢＰ）、砒化ホウ素（ＢＡｓ）、窒化アルミニウム（ＡｌＮ）、リン化アルミニウム（ＡｌＰ）、砒化アルミニウム（ＡｌＡｓ）、アンチモン化アルミニウム（ＡｌＳｂ）、窒化ガリウム（ＧａＮ）、リン化ガリウム（ＧａＰ）、砒化ガリウム（ＧａＡｓ）、アンチモン化ガリウム（ＧａＳｂ）、窒化インジウム（ＩｎＮ）、リン化インジウム（ＩｎＰ）、砒化インジウム（ＩｎＡｓ）、アンチモン化インジウム（ＩｎＳｂ）等の周期表第１３族元素と周期表第１５族元素との化合物（あるいはIII－Ｖ族化合物半導体）、硫化アルミニウム（Ａｌ２Ｓ３）、セレン化アルミニウム（Ａｌ２Ｓｅ３）、硫化ガリウム（Ｇａ２Ｓ３）、セレン化ガリウム（Ｇａ２Ｓｅ３）、テルル化ガリウム（Ｇａ２Ｔｅ３）、酸化インジウム（Ｉｎ２Ｏ３）、硫化インジウム（Ｉｎ２Ｓ３）、セレン化インジウム（Ｉｎ２Ｓｅ３）、テルル化インジウム（Ｉｎ２Ｔｅ３）等の周期表第１３族元素と周期表第１６族元素との化合物、塩化タリウム（Ｉ）（ＴｌＣｌ）、臭化タリウム（Ｉ）（ＴｌＢｒ）、ヨウ化タリウム（Ｉ）（ＴｌＩ）等の周期表第１３族元素と周期表第１７族元素との化合物、酸化亜鉛（ＺｎＯ）、硫化亜鉛（ＺｎＳ）、セレン化亜鉛（ＺｎＳｅ）、テルル化亜鉛（ＺｎＴｅ）、酸化カドミウム（ＣｄＯ）、硫化カドミウム（ＣｄＳ）、セレン化カドミウム（ＣｄＳｅ）、テルル化カドミウム（ＣｄＴｅ）、硫化水銀（ＨｇＳ）、セレン化水銀（ＨｇＳｅ）、テルル化水銀（ＨｇＴｅ）等の周期表第１２族元素と周期表第１６族元素との化合物（あるいはII－VI族化合物半導体）、硫化砒素（III）（Ａｓ２Ｓ３）、セレン化砒素（III）（Ａｓ２Ｓｅ３）、テルル化砒素（III）（Ａｓ２Ｔｅ３）、硫化アンチモン（III）（Ｓｂ２Ｓ３）、セレン化アンチモン（III）（Ｓｂ２Ｓｅ３）、テルル化アンチモン（III）（Ｓｂ２Ｔｅ３）、硫化ビスマス（III）（Ｂｉ２Ｓ３）、セレン化ビスマス（III）（Ｂｉ２Ｓｅ３）、テルル化ビスマス（III）（Ｂｉ２Ｔｅ３）等の周期表第１５族元素と周期表第１６族元素との化合物、酸化銅（Ｉ）（Ｃｕ２Ｏ）、セレン化銅（Ｉ）（Ｃｕ２Ｓｅ）等の周期表第１１族元素と周期表第１６族元素との化合物、塩化銅（Ｉ）（ＣｕＣｌ）、臭化銅（Ｉ）（ＣｕＢｒ）、ヨウ化銅（Ｉ）（ＣｕＩ）、塩化銀（ＡｇＣｌ）、臭化銀（ＡｇＢｒ）等の周期表第１１族元素と周期表第１７族元素との化合物、酸化ニッケル（II）（ＮｉＯ）等の周期表第１０族元素と周期表第１６族元素との化合物、酸化コバルト（II）（ＣｏＯ）、硫化コバルト（II）（ＣｏＳ）等の周期表第９族元素と周期表第１６族元素との化合物、四酸化三鉄（Ｆｅ３Ｏ４）、硫化鉄（II）（ＦｅＳ）等の周期表第８族元素と周期表第１６族元素との化合物、酸化マンガン（II）（ＭｎＯ）等の周期表第７族元素と周期表第１６族元素との化合物、硫化モリブデン（IV）（ＭｏＳ２）、酸化タングステン（IV）（ＷＯ２）等の周期表第６族元素と周期表第１６族元素との化合物、酸化バナジウム（II）（ＶＯ）、酸化バナジウム（IV）（ＶＯ２）、酸化タンタル（Ｖ）（Ｔａ２Ｏ５）等の周期表第５族元素と周期表第１６族元素との化合物、酸化チタン（ＴｉＯ２、Ｔｉ２Ｏ５、Ｔｉ２Ｏ３、Ｔｉ５Ｏ９等）等の周期表第４族元素と周期表第１６族元素との化合物、硫化マグネシウム（ＭｇＳ）、セレン化マグネシウム（ＭｇＳｅ）等の周期表第２族元素と周期表第１６族元素との化合物、酸化カドミウム（II）クロム（III）（ＣｄＣｒ２Ｏ４）、セレン化カドミウム（II）クロム（III）（ＣｄＣｒ２Ｓｅ４）、硫化銅（II）クロム（III）（ＣｕＣｒ２Ｓ４）、セレン化水銀（II）クロム（III）（ＨｇＣｒ２Ｓｅ４）等のカルコゲンスピネル類、バリウムチタネート（ＢａＴｉＯ３）等が挙げられるが、ＳｎＳ２、ＳｎＳ、ＳｎＳｅ、ＳｎＴｅ、ＰｂＳ、ＰｂＳｅ、ＰｂＴｅ等の周期表第１４族元素と周期表第１６族元素との化合物、ＧａＮ、ＧａＰ、ＧａＡｓ、ＧａＳｂ、ＩｎＮ、ＩｎＰ、ＩｎＡｓ、ＩｎＳｂ等のIII－Ｖ族化合物半導体、Ｇａ２Ｏ３、Ｇａ２Ｓ３、Ｇａ２Ｓｅ３、Ｇａ２Ｔｅ３、Ｉｎ２Ｏ３、Ｉｎ２Ｓ３、Ｉｎ２Ｓｅ３、Ｉｎ２Ｔｅ３等の周期表第１３族元素と周期表第１６族元素との化合物、ＺｎＯ、ＺｎＳ、ＺｎＳｅ、ＺｎＴｅ、ＣｄＯ、ＣｄＳ、ＣｄＳｅ、ＣｄＴｅ、ＨｇＯ、ＨｇＳ、ＨｇＳｅ、ＨｇＴｅ等のII－VI族化合物半導体、Ａｓ２Ｏ３、Ａｓ２Ｓ３、Ａｓ２Ｓｅ３、Ａｓ２Ｔｅ３、Ｓｂ２Ｏ３、Ｓｂ２Ｓ３、Ｓｂ２Ｓｅ３、Ｓｂ２Ｔｅ３、Ｂｉ２Ｏ３、Ｂｉ２Ｓ３、Ｂｉ２Ｓｅ３、Ｂｉ２Ｔｅ３等の周期表第１５族元素と周期表第１６族元素との化合物、ＭｇＳ、ＭｇＳｅ等の周期表第２族元素と周期表第１６族元素との化合物が好ましく、中でも、Ｓｉ、Ｇｅ、ＧａＮ、ＧａＰ、ＩｎＮ、ＩｎＰ、Ｇａ２Ｏ３、Ｇａ２Ｓ３、Ｉｎ２Ｏ３、Ｉｎ２Ｓ３、ＺｎＯ、ＺｎＳ、ＣｄＯ、ＣｄＳがより好ましい。これらの物質は、毒性の高い陰性元素を含まないので耐環境汚染性や生物への安全性に優れており、また、可視光領域で純粋なスペクトルを安定して得ることができるので、発光素子の形成に有利である。これらの材料のうち、ＣｄＳｅ、ＺｎＳｅ、ＣｄＳは、発光の安定性の点で好ましい。発光効率、高屈折率、安全性の経済性の観点から、ＺｎＯ、ＺｎＳの量子ドットが好ましい。また、上記の材料は、１種で用いるものであってもよいし、２種以上を組み合わせて用いてもよい。 Examples of the constituent material of the quantum dot include a simple substance of a periodic table group 14 element such as carbon, silicon, germanium, and tin, a simple substance of a periodic table group 15 element such as phosphorus (black phosphorus), and a periodicity of selenium, tellurium, and the like. Table 16 group element simple substance, compound consisting of a plurality of periodic table group 14 elements such as silicon carbide (SiC), tin oxide (IV) (SnO 2 ), tin sulfide (II, IV) (Sn (II) Sn (IV) S 3 ), tin sulfide (IV) (SnS 2 ), tin (II) sulfide (SnS), tin (II) selenide (SnSe), tin telluride (II) (SnTe), lead sulfide (II) ) (PbS), lead selenide (II) (PbSe), lead telluride (II) (PbTe) periodic table group 14 element and periodic table group 16 element compound, boron nitride (BN), phosphorus Boron halide (BP), Boron arsenide (BAs), Aluminum nitride (AlN), Al phosphide Ni (AlP), aluminum arsenide (AlAs), aluminum antimonide (AlSb), gallium nitride (GaN), gallium phosphide (GaP), gallium arsenide (GaAs), gallium antimonide (GaSb), indium nitride (InN), Compounds of Group 13 elements of the periodic table and Group 15 elements of the periodic table such as indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb), etc. (or III-V group compound semiconductors), aluminum sulfide ( Al 2 S 3 ), aluminum selenide (Al 2 Se 3 ), gallium sulfide (Ga 2 S 3 ), gallium selenide (Ga 2 Se 3 ), gallium telluride (Ga 2 Te 3 ), indium oxide (In 2) O 3), indium sulfide (In 2 S 3), indium selenide (I 2 Se 3), compounds of tellurium indium (In 2 Te 3) periodic table group 13 elements and the periodic table group 16 element such as, thallium chloride (I) (TlCl), thallium bromide (I) (TlBr ), Compounds of group 13 elements of the periodic table and elements of group 17 of the periodic table such as thallium (I) iodide (TlI), zinc oxide (ZnO), zinc sulfide (ZnS), zinc selenide (ZnSe), tellurium Zinc iodide (ZnTe), cadmium oxide (CdO), cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium telluride (CdTe), mercury sulfide (HgS), mercury selenide (HgSe), mercury telluride (HgTe) ) periodic table group 12 element and the periodic table compound of group 16 element such as (or II-VI compound semiconductor), arsenic sulfide (III) (as 2 S 3), selenium arsenic (III (As 2 Se 3), telluride arsenic (III) (As 2 Te 3 ), antimony sulfide (III) (Sb 2 S 3 ), selenium antimony (III) (Sb 2 Se 3 ), antimony telluride (III ) (Sb 2 Te 3 ), bismuth sulfide (III) (Bi 2 S 3 ), bismuth selenide (III) (Bi 2 Se 3 ), bismuth telluride (III) (Bi 2 Te 3 ), etc. Compounds of Group 15 elements and Group 16 elements of the periodic table, Group 11 elements of the periodic table and Group 16 of the periodic table such as copper (I) (Cu 2 O), copper selenide (Cu 2 Se), etc. Periodic tables of compounds with elements, copper chloride (I) (CuCl), copper bromide (I) (CuBr), copper iodide (I) (CuI), silver chloride (AgCl), silver bromide (AgBr), etc. Compounds of Group 11 elements and Periodic Table Group 17 elements, nickel oxide (II) (N compounds of periodic table group 10 elements such as iO) and periodic table group 16 elements, periodic table group 9 elements such as cobalt (II) oxide (CoO), cobalt sulfide (II) (CoS) and periodic table Compounds with Group 16 elements, compounds of Group 8 elements of the periodic table such as triiron tetroxide (Fe 3 O 4 ), iron (II) sulfide (FeS), and Group 16 elements of the periodic table, manganese (II) oxide A compound of a periodic table group 7 element such as (MnO) and a periodic table group 16 element, a periodic table group 6 element such as molybdenum sulfide (IV) (MoS 2 ), tungsten oxide (IV) (WO 2 ), etc. Compounds with Group 16 elements of the Periodic Table, Periodic Table Group 5 elements such as vanadium (II) oxide (VO), vanadium oxide (IV) (VO 2 ), tantalum oxide (V) (Ta 2 O 5 ) and the period Table compound of group 16 element, a titanium oxide (TiO 2, Ti 2 O 5 , Ti 2 O , A compound of Group 4 of the periodic table element and Periodic Table Group 16 element of Ti 5 O 9, etc.) and the like, magnesium sulfide (MgS), the second group elements and the periodic table periodic table such as magnesium selenide (MgSe) Compounds with group 16 elements, cadmium (II) chromium (III) (CdCr 2 O 4 ), cadmium selenide (II) chromium (III) (CdCr 2 Se 4 ), copper sulfide (II) chromium (III) ( Examples thereof include chalcogen spinels such as CuCr 2 S 4 ), mercury (II) selenide, chromium (III) (HgCr 2 Se 4 ), barium titanate (BaTiO 3 ), etc., but SnS 2 , SnS, SnSe, SnTe, PbS , PbSe, PbTe, etc. compounds of periodic table group 14 elements and periodic table group 16 elements, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, etc. III-V group compound semiconductors such as Ga 2 O 3 , Ga 2 S 3 , Ga 2 Se 3 , Ga 2 Te 3 , In 2 O 3 , In 2 S 3 , In 2 Se 3 , In 2 Te 3, etc. Compounds of Group 13 elements and Group 16 elements of the periodic table, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgO, HgS, HgSe, HgTe and other II-VI group compound semiconductors, As 2 O 3 , As 2 S 3 , As 2 Se 3 , As 2 Te 3 , Sb 2 O 3 , Sb 2 S 3 , Sb 2 Se 3 , Sb 2 Te 3 , Bi 2 O 3 , Bi 2 S 3 , Bi 2 A compound of a periodic table group 15 element such as Se 3 or Bi 2 Te 3 and a group 16 element of the periodic table, a compound of periodic table group 2 element such as MgS or MgSe, and a group 16 element of the periodic table are preferable, Among them, Si, Ge GaN, GaP, InN, InP, Ga 2 O 3 , Ga 2 S 3 , In 2 O 3 , In 2 S 3 , ZnO, ZnS, CdO, and CdS are more preferable. Since these substances do not contain highly toxic negative elements, they are excellent in environmental pollution resistance and safety to living organisms, and since a pure spectrum can be stably obtained in the visible light region, light emitting devices Is advantageous for the formation of Of these materials, CdSe, ZnSe, and CdS are preferable in terms of light emission stability. From the viewpoints of luminous efficiency, high refractive index, and safety, ZnO and ZnS quantum dots are preferable. Moreover, said material may be used by 1 type and may be used in combination of 2 or more type.
　なお、上述した量子ドットには、必要に応じて微量の各種元素を不純物としてドープすることができる。このようなドープ物質を添加することにより発光特性を大きく向上させることができる。 Note that the above-described quantum dots can be doped with a small amount of various elements as impurities as necessary. By adding such a doping substance, the emission characteristics can be greatly improved.
　本発明に係る量子ドットにおいては、発光波長が４１３～４７７ｎｍ（２．６～３．６ｅＶ）としての範囲内にあることを特徴とする。 The quantum dot according to the present invention is characterized in that the emission wavelength is in the range of 413 to 477 nm (2.6 to 3.6 eV).
　本発明でいう発光波長（バンドギャップ）とは、無機物である量子ドットの場合は、価電子帯と伝導帯のエネルギー差を量子ドットにおけるバンドギャップ（ｅＶ）であり、発光波長（ｎｍ）＝１２４０／バンドギャップ（ｅＶ）で表される。 The emission wavelength (band gap) as used in the present invention is the band gap (eV) in a quantum dot, and the emission wavelength (nm) = 1240 in the case of an inorganic quantum dot. / Band gap (eV).
　量子ドットのバンドギャップ（ｅＶ）は、Ｔａｕｃプロットを用いて測定することができる。 The band gap (eV) of a quantum dot can be measured using a Tauc plot.
　バンドギャップ（ｅＶ）の光科学的測定手法の一つであるＴａｕｃプロットについて説明する。 The Tauc plot, which is one of the optical scientific measurement methods of the band gap (eV), will be described.
　Ｔａｕｃプロットを用いたバンドギャップ（Ｅ０）の測定原理を以下に示す。 The measurement principle of the band gap (E 0 ) using the Tauc plot is shown below.
　半導体材料の長波長側の光学吸収端近傍の比較的吸収の大きい領域に於いて光吸収係数αと光エネルギーｈν（ただし、ｈはプランク常数、νは振動数）、及びバンドキャップエネルギーＥ０の間には次式（Ａ）、が成り立つと考えられている。 In the region of relatively large absorption near the optical absorption edge on the long wavelength side of the semiconductor material, the light absorption coefficient α, the light energy hν (where h is the Planck constant, ν is the vibration frequency), and the band cap energy E 0 In the meantime, the following equation (A) is considered to hold.
　式（Ａ）
　　　αｈν＝Ｂ（ｈν－Ｅ０）２
　従って、吸収スペクトルを測定し、そこから（αｈν）の０．５乗に対してｈνをプロット（いわゆる、Ｔａｕｃプロット）し、直線区間を外挿したα＝０におけるｈνの値が求めようとする量子ドットのバンドギャップエネルギーＥ0となる。 Formula (A)
αhν = B (hν−E 0 ) 2
Therefore, an absorption spectrum is measured, and hν is plotted (so-called Tauc plot) with respect to (αhν) raised to the 0.5th power, and the value of hν at α = 0 with extrapolation of the straight section is sought. It becomes the band gap energy E 0 of the quantum dot.
　なお、量子ドットの場合は、吸収と発光のスペクトルの差異（ストークスシフト）が小さく、また波形もシャープであるため、簡便には発光スペクトルの極大波長をバンドギャップの指標として用いることもできる。 In the case of quantum dots, the difference between absorption and emission spectra (Stokes shift) is small and the waveform is sharp, so the maximum wavelength of the emission spectrum can be used as an index of the band gap.
　また、他の方法として、これら有機及び無機機能材料のエネルギー準位を見積もる方法としては、走査型トンネル分光法、紫外線光電子分光法、Ｘ線光電子分光法、オージェ電子分光法により求められるエネルギー準位から求める方法及び光学的にバンドギャップを見積もる方法が挙げられる。 As another method for estimating the energy levels of these organic and inorganic functional materials, energy levels required by scanning tunneling spectroscopy, ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, Auger electron spectroscopy are used. And a method for optically estimating the band gap.
　また、これら量子ドットは、ホールと電子が量子ドット内での直接再結合することによる発光だけでなく、有機電子ブロック正孔輸送層や有機発光層、又は正孔ブロック電子輸送層中で生じた励起子のエネルギーを量子ドットに吸収させ量子ドットのコアからの発光を得ても良い。これらの量子ドットは、低濃度ドープされているため、その他のリン光発光性化合物にも励起子のエネルギーを吸収させて発光を得ることができる。 In addition, these quantum dots were generated not only in light emission due to direct recombination of holes and electrons in the quantum dots, but also in an organic electron block hole transport layer, an organic light emission layer, or a hole block electron transport layer. The energy of excitons may be absorbed by the quantum dots to obtain light emission from the quantum dot core. Since these quantum dots are lightly doped, other phosphorescent compounds can also absorb the exciton energy to obtain light emission.
　量子ドットの表面は、不活性な無機物の被覆層又は有機配位子で構成された被膜で被覆されたものであるのが好ましい。すなわち、量子ドットの表面は、量子ドット材料で構成されたコア領域と、不活性な無機物の被覆層又は有機配位子で構成されたシェル領域とを有するコア／シェル構造を有するものであるのが好ましい。 The surface of the quantum dot is preferably coated with an inert inorganic coating layer or a coating composed of an organic ligand. That is, the surface of the quantum dot has a core / shell structure having a core region made of a quantum dot material and a shell region made of an inert inorganic coating layer or an organic ligand. Is preferred.
　このコア／シェル構造は、少なくとも２種類の化合物で形成さていることが好ましく、２種類以上の化合物でグラジエント構造（傾斜構造）を形成していても良い。これにより、塗布液中における量子ドットの凝集を効果的に防止することができ、量子ドットの分散性を向上させることができるとともに、輝度効率が向上し、連続駆動させた場合に生じる色ズレを抑制することができる。また、被覆層の存在により、安定的に発光特性が得られる。 This core / shell structure is preferably formed of at least two kinds of compounds, and a gradient structure (gradient structure) may be formed of two or more kinds of compounds. This effectively prevents aggregation of the quantum dots in the coating liquid, improves the dispersibility of the quantum dots, improves the luminance efficiency, and prevents color shifts that occur when driven continuously. Can be suppressed. Further, the light emission characteristics can be stably obtained due to the presence of the coating layer.
　また、量子ドットの表面が被膜（シェル部）で被覆されていると、後述するような表面修飾剤を量子ドットの表面付近に確実に担持させることができる。 In addition, when the surface of the quantum dot is covered with a coating (shell part), a surface modifier as described later can be reliably supported in the vicinity of the surface of the quantum dot.
　被膜（シェル部）の厚さは、特に限定されないが、０．１～１０ｎｍの範囲内であることが好ましく、０．１～５ｎｍの範囲内であることがより好ましい。 The thickness of the coating (shell part) is not particularly limited, but is preferably in the range of 0.1 to 10 nm, and more preferably in the range of 0.1 to 5 nm.
　一般に、量子ドットの平均粒子径をコントロールすることにより、発光色を制御することができ、被膜の厚さが上記範囲内の値であれば、被膜の厚さが原子数個分に相当する厚さから量子ドット１個に満たない厚さであり、量子ドットを高密度で充填することができ、十分な発光量が得られる。また、被膜の存在により、お互いのコア粒子の粒子表面に存在する欠陥、ダングリングボンドへの電子トラップによる非発光の電子エネルギーの転移を抑制でき、量子効率の低下を抑えることができる。 In general, the emission color can be controlled by controlling the average particle diameter of the quantum dots. If the thickness of the coating is a value within the above range, the thickness of the coating corresponds to the number of atoms. Thus, the thickness is less than one quantum dot, the quantum dots can be filled with high density, and a sufficient amount of light emission can be obtained. In addition, the presence of the coating can suppress non-luminous electron energy transfer due to defects existing on the particle surfaces of the core particles and electron traps on the dangling bonds, thereby suppressing a decrease in quantum efficiency.
　（４．４）機能性の表面修飾剤
　量子ドットを含有している有機機能層を湿式塗布方式で形成する際、それに用いる塗布液中においては、量子ドットの表面近傍に、表面修飾剤が付着している状態であることが好ましい。これにより、塗布液中における量子ドットの分散安定性を特に優れた状態とすることができる。また、量子ドットの製造時において、量子ドット表面に表面修飾剤を付着させることにより、形成される量子ドットの形状が真球度の高いものとなり、また、量子ドットの粒子径分布を狭く抑えられるため、特に優れたものとすることができる。 (4.4) Functional surface modifier When forming an organic functional layer containing quantum dots by a wet coating method, a surface modifier is attached in the vicinity of the surface of the quantum dots in the coating solution used therefor. It is preferable that it is the state which is carrying out. Thereby, the dispersion stability of the quantum dots in the coating liquid can be made particularly excellent. In addition, when a quantum dot is manufactured, by attaching a surface modifier to the surface of the quantum dot, the shape of the formed quantum dot becomes highly spherical, and the particle size distribution of the quantum dot can be kept narrow. Therefore, it can be made particularly excellent.
　本発明で適用可能な機能性の表面修飾剤としては、量子ドットの表面に直接付着したものであってもよいし、シェルを介して付着したもの（表面修飾剤が直接付着するのはシェルで、量子ドットのコア部には接触していないもの）であってもよい。 Functional surface modifiers applicable in the present invention may be those directly attached to the surface of the quantum dots, or those attached via a shell (the surface modifier is directly attached to the shell. In other words, it may not be in contact with the core of the quantum dot.
　表面修飾剤としては、例えば、ポリオキシエチレンラウリルエーテル、ポリオキシエチレンステアリルエーテル、ポリオキシエチレンオレイルエーテル等のポリオキシエチレンアルキルエーテル類；トリプロピルホスフィン、トリブチルホスフィン、トリヘキシルホスフィン、トリオクチルホスフィン等のトリアルキルホスフィン類；ポリオキシエチレンｎ－オクチルフェニルエーテル、ポリオキシエチレンｎ－ノニルフェニルエーテル等のポリオキシエチレンアルキルフェニルエーテル類；トリ（ｎ－ヘキシル）アミン、トリ（ｎ－オクチル）アミン、トリ（ｎ－デシル）アミン等の第３級アミン類；トリプロピルホスフィンオキシド、トリブチルホスフィンオキシド、トリヘキシルホスフィンオキシド、トリオクチルホスフィンオキシド、トリデシルホスフィンオキシド等の有機リン化合物；ポリエチレングリコールジラウレート、ポリエチレングリコールジステアレート等のポリエチレングリコールジエステル類；ピリジン、ルチジン、コリジン、キノリン類の含窒素芳香族化合物等の有機窒素化合物；ヘキシルアミン、オクチルアミン、デシルアミン、ドデシルアミン、テトラデシルアミン、ヘキサデシルアミン、オクタデシルアミン等のアミノアルカン類；ジブチルスルフィド等のジアルキルスルフィド類；ジメチルスルホキシドやジブチルスルホキシド等のジアルキルスルホキシド類；チオフェン等の含硫黄芳香族化合物等の有機硫黄化合物；パルミチン酸、ステアリン酸、オレイン酸等の高級脂肪酸；アルコール類；ソルビタン脂肪酸エステル類；脂肪酸変性ポリエステル類；３級アミン変性ポリウレタン類；ポリエチレンイミン類等が挙げられるが、量子ドットが後述するような方法で調製されるものである場合、表面修飾剤としては、高温液相において量子ドットの微粒子に配位して、安定化する物質であるのが好ましく、具体的には、トリアルキルホスフィン類、有機リン化合物、アミノアルカン類、第３級アミン類、有機窒素化合物、ジアルキルスルフィド類、ジアルキルスルホキシド類、有機硫黄化合物、高級脂肪酸、アルコール類が好ましい。このような表面修飾剤を用いることにより、塗布液中における量子ドットの分散性を特に優れたものとすることができる。また、量子ドットの製造時において形成される量子ドットの形状をより真球度の高いものとし、量子ドットの粒度分布をよりシャープなものとすることができる。 Examples of the surface modifier include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; tripropylphosphine, tributylphosphine, trihexylphosphine, trioctylphosphine, and the like. Trialkylphosphines; polyoxyethylene alkylphenyl ethers such as polyoxyethylene n-octylphenyl ether and polyoxyethylene n-nonylphenyl ether; tri (n-hexyl) amine, tri (n-octyl) amine, tri ( tertiary amines such as n-decyl) amine; tripropylphosphine oxide, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphineoxy Organic phosphorus compounds such as tridecylphosphine oxide; polyethylene glycol diesters such as polyethylene glycol dilaurate and polyethylene glycol distearate; organic nitrogen compounds such as nitrogen-containing aromatic compounds such as pyridine, lutidine, collidine and quinolines; hexylamine; Aminoalkanes such as octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine; dialkyl sulfides such as dibutyl sulfide; dialkyl sulfoxides such as dimethyl sulfoxide and dibutyl sulfoxide; sulfur-containing aromatics such as thiophene Organic sulfur compounds such as compounds; higher fatty acids such as palmitic acid, stearic acid and oleic acid; alcohols; sorbitan fatty acid esters; fatty acid-modified poly Stealtes; tertiary amine-modified polyurethanes; polyethyleneimines and the like. When the quantum dots are prepared by the method described later, the surface modifier may be a fine particle of quantum dots in a high-temperature liquid phase. It is preferable that the substance is coordinated to be stabilized, specifically, trialkylphosphines, organic phosphorus compounds, aminoalkanes, tertiary amines, organic nitrogen compounds, dialkyl sulfides, dialkyl sulfoxides. , Organic sulfur compounds, higher fatty acids and alcohols are preferred. By using such a surface modifier, the dispersibility of the quantum dots in the coating solution can be made particularly excellent. Moreover, the shape of the quantum dot formed at the time of manufacture of a quantum dot can be made into a higher sphericity, and the particle size distribution of a quantum dot can be made sharper.
　本発明において、前述のように、量子ドットのサイズ（平均粒子径）としては、１～２０ｎｍの範囲内であることが好ましい。本発明において、量子ドットのサイズとは、量子ドット材料で構成されたコア領域と、不活性な無機物の被覆層又は有機配位子で構成されたシェル領域及び表面修飾剤で構成されるトータルのサイズを表す。表面修飾剤やシェルが含まれない場合は、それを含まないサイズを表す。 In the present invention, as described above, the size (average particle diameter) of the quantum dots is preferably in the range of 1 to 20 nm. In the present invention, the size of the quantum dots means the total area composed of a core region composed of a quantum dot material, a shell region composed of an inert inorganic coating layer or an organic ligand, and a surface modifier. Represents size. If the surface modifier or shell is not included, the size does not include it.
　（４．５）量子ドットの製造方法
　量子ドットの製造方法としては、従来行われている下記のような量子ドットの製造方法等を適用することができるが、これらに限定されるものではなく公知の任意の方法を用いることができる。また、Ａｌｄｒｉｃｈ社、ＣｒｙｓｔａｌＰｌｅｘ社、ＮＮＬａｂ社等から市販品として購入することもできる。 (4.5) Manufacturing Method of Quantum Dots As a manufacturing method of quantum dots, the following conventional manufacturing method of quantum dots can be applied, but is not limited to these and is publicly known. Any method can be used. Moreover, it can also be purchased as a commercial item from Aldrich, CrystalPlex, NNLab, etc.
　例えば、高真空下のプロセスとしては、分子ビームエピタキシー法、ＣＶＤ法等；液相製造方法としては、原料水溶液を、例えば、ｎ－ヘプタン、ｎ－オクタン、イソオクタン等のアルカン類、又はベンゼン、トルエン、キシレン等の芳香族炭化水素等の非極性有機溶媒中の逆ミセルとして存在させ、この逆ミセル相中にて結晶成長させる逆ミセル法、熱分解性原料を高温の液相有機媒体に注入して結晶成長させるホットソープ法、さらに、ホットソープ法と同様に、酸塩基反応を駆動力として比較的低い温度で結晶成長を伴う溶液反応法等が挙げられる。これらの製造方法から任意の方法を使用することができるが、中でも、液相製造方法が好ましい。 For example, as a process under high vacuum, a molecular beam epitaxy method, a CVD method, etc .; As a liquid phase production method, an aqueous raw material is used, for example, alkanes such as n-heptane, n-octane, isooctane, or benzene, toluene. Inverted micelles, which exist as reverse micelles in non-polar organic solvents such as aromatic hydrocarbons such as xylene, and crystal growth in this reverse micelle phase, inject a thermally decomposable raw material into a high-temperature liquid-phase organic medium Examples thereof include a hot soap method for crystal growth and a solution reaction method involving crystal growth at a relatively low temperature using an acid-base reaction as a driving force, as in the hot soap method. Any method can be used from these production methods, and among these, the liquid phase production method is preferred.
　なお、液相製造方法において、量子ドットの合成に際して、表面に存在する有機表面修飾剤を初期表面修飾剤という。例えば、ホットソープ法における初期表面修飾剤の例としては、トリアルキルホスフィン類、トリアルキルホスフィンオキシド類、アルキルアミン類、ジアルキルスルホキシド類、アルカンホスホン酸等が挙げられる。これらの初期表面修飾剤は、交換反応により上述の機能性表面修飾剤に交換することが好ましい。 In the liquid phase production method, the organic surface modifier present on the surface when the quantum dots are synthesized is referred to as an initial surface modifier. For example, examples of the initial surface modifier in the hot soap method include trialkylphosphines, trialkylphosphine oxides, alkylamines, dialkyl sulfoxides, alkanephosphonic acid and the like. These initial surface modifiers are preferably exchanged for the above-described functional surface modifiers by an exchange reaction.
　具体的には、例えば、上記ホットソープ法により得られるトリオクチルホスフィンオキシド等の初期表面修飾剤は、機能性表面修飾剤を含有する液相中で行う交換反応により、上述の機能性表面修飾剤と交換することが可能である。 Specifically, for example, the initial surface modifier such as trioctylphosphine oxide obtained by the hot soap method is the above-described functional surface modifier by an exchange reaction performed in a liquid phase containing the functional surface modifier. It is possible to exchange with.
　以下に、量子ドットの製造方法の一例を示す。 The following shows an example of a method for producing quantum dots.
　〈１〉量子ドットの製造例１
　まず、ＣｄＯパウダー（１．６ｍｍｏｌ、０．２０６ｇ；Ａｌｄｒｉｃｈ、＋９９．９９％）とオレイン酸（６．４ｍｍｏｌ、１．８ｇ；Ａｌｄｒｉｃｈ、９５％）とを４０ｍｌのトリオクチルアミン（ＴＯＡ、Ａｌｄｒｉｃｈ、９５％）中で混合する。混合された溶液（Ｃｄ－含有混合物）を高速で撹拌しながら１５０℃で熱処理し、Ｎ２を流しながら３００℃まで温度を上昇させた。次いで、３００℃で、トリオクチルホスフィン（ＴＯＰ、Ｓｔｒｅｍ、９７％）に添加された２．０モル／ＬのＳｅ（Ａｌｆａ　Ａｅｓａｒ）０．２ｍｌを、上記Ｃｄ－含有混合物に高速で注入する。 <1> Production example 1 of quantum dots
First, CdO powder (1.6 mmol, 0.206 g; Aldrich, + 99.99%) and oleic acid (6.4 mmol, 1.8 g; Aldrich, 95%) were mixed with 40 ml of trioctylamine (TOA, Aldrich, 95 %). The mixed solution (Cd-containing mixture) was heat-treated at 150 ° C. while stirring at high speed, and the temperature was raised to 300 ° C. while flowing N 2 . Then, at 300 ° C., 0.2 ml of 2.0 mol / L Se (Alfa Aesar) added to trioctylphosphine (TOP, Strem, 97%) is injected into the Cd-containing mixture at high speed.
　９０秒後、上記溶液に、ＴＯＡ（２１０μｌ　ｉｎ６ｍｌ）に添加された１．２ｍｍｏｌのｎ－オクタンチオールを、注射器ポンプ（ｓｙｒｉｎｇｅ　ｐｕｍｐ）を用いて１ｍｌ／ｍｉｎの速度で注入して４０分間反応させる。これを、Ｃｄ－含有反応媒質と称す。 After 90 seconds, 1.2 mmol of n-octanethiol added to TOA (210 μl in 6 ml) is injected into the above solution at a rate of 1 ml / min using a syringe pump and allowed to react for 40 minutes. This is referred to as a Cd-containing reaction medium.
　次に、０．９２ｇの酢酸亜鉛と２．８ｇのオレイン酸とを２０ｍｌのＴＯＡに２００℃で、Ｎ２雰囲気下で溶解させて０．２５モル／ＬのＺｎ前駆体溶液を調製する。 Next, 0.92 g of zinc acetate and 2.8 g of oleic acid are dissolved in 20 ml of TOA at 200 ° C. in an N 2 atmosphere to prepare a 0.25 mol / L Zn precursor solution.
　次いで、１６ｍｌのアリコート（ａｌｉｑｕｏｔ）のＺｎ－オレイン酸溶液（１００℃で加熱された上記Ｚｎ前駆体溶液）を前記Ｃｄ－含有反応媒質に２ｍｌ／ｍｉｎの速度で注入する。その後、ＴＯＡ（１．１２ｍｌ　ｉｎ　６ｍｌ）中の６．４ｍｍｏｌのｎ－オクタンチオールを、注射器ポンプを用いて１ｍｌ／ｍｉｎの速度で注入する。 Next, a 16 ml aliquot of Zn-oleic acid solution (the Zn precursor solution heated at 100 ° C.) is injected into the Cd-containing reaction medium at a rate of 2 ml / min. Thereafter, 6.4 mmol of n-octanethiol in TOA (1.12 ml in 6 ml) is injected at a rate of 1 ml / min using a syringe pump.
　全体反応は、２時間かけて行う。反応が終わった後、生成物を約５０～６０℃に冷却し、有機スラッジを遠心分離（５，６００ｒｐｍ）で除去する。不透明な塊がなくなるまでエタノール（Ｆｉｓｈｅｒ、ＨＰＬＣ　ｇｒａｄｅ）を添加する。次いで、遠心分離して得られた沈殿物をトルエン（Ｓｉｇｍａ－Ａｌｄｒｉｃｈ、Ａｎｈｙｄｒｏｕｓ　９９．８％）中で溶解させることにより、ＣｄＳｅ／ＣｄＳ／ＺｎＳコア－シェル量子ドットコロイド溶液をえることができる。 The entire reaction takes 2 hours. After the reaction is complete, the product is cooled to about 50-60 ° C. and the organic sludge is removed by centrifugation (5,600 rpm). Add ethanol (Fisher, HPLC grade) until there is no opaque mass. Subsequently, the precipitate obtained by centrifugation is dissolved in toluene (Sigma-Aldrich, Anhydrous 99.8%), whereby a CdSe / CdS / ZnS core-shell quantum dot colloidal solution can be obtained.
　〈２〉量子ドットの製造例２
　ＣｄＳｅ／ＺｎＳのコア／シェル構造を有する量子ドットを得ようとする場合、界面活性剤としてＴＯＰＯ（ｔｒｉｏｃｔｙｌｐｈｏｓｐｈｉｎｅ ｏｘｉｄｅ）を使用した有機溶媒に（ＣＨ３）２Ｃｄ（ｄｉｍｅｔｈｙｌ ｃａｄｍｉｕｍ）、ＴＯＰＳｅ（ｔｒｉｏｃｔｙｌｐｈｏｓｐｈｉｎｅ ｓｅｌｅｎｉｄｅ）などのコア（ＣｄＳｅ）に該当する前駆体物質を注入して結晶が生成されるようにし、結晶が一定の大きさで成長するように高温で一定時間維持した後、シェル（ＺｎＳ）に該当する前駆体物質を注入して既に生成されたコアの表面にシェルが形成されるようにすることで、ＴＯＰＯでキャッピング（ｃａｐｐｉｎｇ）されたＣｄＳｅ／ＺｎＳの量子ドットを得ることができる。 <2> Production example 2 of quantum dots
When a quantum dot having a core / shell structure of CdSe / ZnS is to be obtained, (CH 3 ) 2 Cd (dimethyl cadmium), TOPSe (trioctylphosphine selenium) is used as an organic solvent using TOPO (trioxyphosphine oxide) as a surfactant. A precursor material corresponding to the core (CdSe) is injected to generate a crystal, and is maintained at a high temperature for a certain period of time so that the crystal grows at a certain size, and then corresponds to the shell (ZnS). CdSe / ZnS quantum dots capped with TOPO can be obtained by injecting the precursor material so that a shell is formed on the surface of the core already formed.
　〈３〉量子ドットの製造例３
　アルゴン気流下、トリ－ｎ－オクチルホスフィンオキシド（ＴＯＰＯ）（関東化学社製）７．５ｇに、ステアリン酸（関東化学社製）２．９ｇ、ｎ－テトラデシルホスホン酸（ＡＶＯＣＡＤＯ社製）６２０ｍｇ、及び、酸化カドミニウム（和光純薬工業社製）２５０ｍｇを加え、３７０℃に加熱混合した。これを２７０℃まで自然冷却させた後、予めトリブチルホスフィン（関東化学社製）２．５ｍＬにセレン（ＳＴＲＥＭ ＣＨＥＭＩＣＡＬ社製）２００ｍｇを溶解させた溶液を加え、減圧乾燥し、ＴＯＰＯで被覆されたＣｄＳｅ微粒子を得る。 <3> Production example 3 of quantum dots
Under an argon stream, 7.5 g of tri-n-octylphosphine oxide (TOPO) (manufactured by Kanto Chemical Co.), 2.9 g of stearic acid (manufactured by Kanto Chemical Co., Ltd.), 620 mg of n-tetradecylphosphonic acid (manufactured by AVOCADO), And 250 mg of cadmium oxide (made by Wako Pure Chemical Industries Ltd.) was added, and it heat-mixed at 370 degreeC. After naturally cooling this to 270 ° C., a solution of 200 mg of selenium (STREM CHEMICAL) dissolved in 2.5 mL of tributylphosphine (manufactured by Kanto Chemical Co., Inc.) was added in advance, dried under reduced pressure, and CdSe coated with TOPO. Get fine particles.
　次いで、得られたＣｄＳｅ微粒子に、ＴＯＰＯ１５ｇを加えて加熱し、引き続き２７０℃でトリオクチルホスフィン（ＴＯＰ、シグマアルドリッチ社製）１０ｍＬにジエチルジチオカルバミン酸亜鉛（東京化成社製）１．１ｇを溶解した溶液を加え、表面にＴＯＰＯが固定された、ＣｄＳｅのナノ結晶をコアとし、ＺｎＳをシェルとするナノ粒子（以下、ＴＯＰＯ固定量子ドットともいう）を得た。なお、この状態の量子ドットは、トルエンやテトラヒドロフラン（ＴＨＦ）等の有機溶媒に可溶である。 Next, 15 g of TOPO was added to the obtained CdSe fine particles and heated, and subsequently, a solution of 1.1 g of zinc diethyldithiocarbamate (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved in 10 mL of trioctylphosphine (TOP, manufactured by Sigma Aldrich) at 270 ° C. Were added, and nanoparticles having CdSe nanocrystals with a core fixed to the surface and ZnS as a shell (hereinafter also referred to as TOPO fixed quantum dots) were obtained. In addition, the quantum dot of this state is soluble in organic solvents, such as toluene and tetrahydrofuran (THF).
　その後、作製したＴＯＰＯ固定量子ドットをＴＨＦに溶解させて８５℃に加温し、そこにエタノールに溶解させたＮ－［（Ｓ）－３－メルカプト－２－メチルプロピオニル］－Ｌ－プロリン（シグマアルドリッチ社製）１００ｍｇを滴下させ、１２時間程度還流させた。１２時間還流後、ＮａＯＨ水溶液を加え、２時間、９０℃で加熱してＴＨＦを蒸発させた。得られた未精製の量子ドットを、限外濾過（Ｍｉｌｌｉｐｏｒｅ社製、「Ｍｉｃｒｏｃｏｎ」）及びセファデックスカラム（Ａｍｅｒｓｈａｍ Ｂｉｏｓｃｉｅｎｃｅｓ社製、「ＭｉｃｒｏＳｐｉｎ Ｇ－２５Ｃｏｌｕｍｎｓ」）を用いて精製と濃縮とを行うことで、量子ドットの表面にＮ－［（Ｓ）－３－メルカプト－２－メチルプロピオニル］－Ｌ－プロリンが固定された親水性の量子ドットを製造することができる。 Thereafter, the prepared TOPO fixed quantum dots were dissolved in THF, heated to 85 ° C., and N-[(S) -3-mercapto-2-methylpropionyl] -L-proline (Sigma) dissolved in ethanol there. (Aldrich) 100 mg was added dropwise and refluxed for about 12 hours. After refluxing for 12 hours, an aqueous NaOH solution was added, and the mixture was heated at 90 ° C. for 2 hours to evaporate THF. By purifying and concentrating the obtained unpurified quantum dots using ultrafiltration (Millipore, “Microcon”) and Sephadex column (Amersham Biosciences, “MicroSpin G-25 Columns”). A hydrophilic quantum dot in which N-[(S) -3-mercapto-2-methylpropionyl] -L-proline is immobilized on the surface of the quantum dot can be produced.
　（４．６）量子ドットの製膜方法
　量子ドットの製膜方法は、ウェットプロセスによるものが好ましい。例えば、スピンコート法、キャスト法、ダイコート法、ブレードコート法、ローラーコート法、インクジェット法、印刷法、スプレーコート法、カーテンコート法、ＬＢ法（ラングミュア・ブロジェット（Ｌａｎｇｍｕｉｒ　Ｂｌｏｄｇｅｔｔ法）等を挙げることができる。 (4.6) Quantum Dot Film Formation Method The quantum dot film formation method is preferably a wet process. For example, spin coating method, casting method, die coating method, blade coating method, roller coating method, ink jet method, printing method, spray coating method, curtain coating method, LB method (Langmuir Brodgett method), etc. Can do.
　更に、量子ドットの単分子膜を他の媒体上に形成した後に転写するような転写方法（フィルム転写法、スタンプ転写法等）による製膜方法も有用である。 Furthermore, a film forming method using a transfer method (film transfer method, stamp transfer method, etc.) in which a quantum dot monomolecular film is formed on another medium and then transferred is also useful.
　この際、用いる溶媒としては、沸点が１００～１５０℃の範囲内にある溶媒を含むことが好ましい。このような沸点範囲の溶媒を用いることで、適切な乾燥速度となり、塗布膜に含まれる量子ドット化合物が適切に配向させることができ、より高い発光効率と耐久性を得ることができるようになる。 In this case, the solvent to be used preferably includes a solvent having a boiling point in the range of 100 to 150 ° C. By using a solvent having such a boiling range, an appropriate drying speed is obtained, the quantum dot compound contained in the coating film can be properly oriented, and higher luminous efficiency and durability can be obtained. .
　このような溶媒としては、トルエン、キシレン、クロロベンゼン、ｎ－ブタノール等を上げることができる。また、これらの溶媒を含む混合溶媒でもよく、その比率としては９：１～０：１０の範囲内であることが好ましい。 As such a solvent, toluene, xylene, chlorobenzene, n-butanol and the like can be raised. Further, a mixed solvent containing these solvents may be used, and the ratio is preferably in the range of 9: 1 to 0:10.
　次いで、本発明の有機ＥＬ素子の各構成要素の詳細について説明する。 Next, details of each component of the organic EL element of the present invention will be described.
　《陽極》
　本発明の有機ＥＬ素子を構成する陽極としては、仕事関数の大きい（４ｅＶ以上）金属、合金、電気伝導性化合物及びこれらの混合物を電極物質とするものが好ましく用いられる。このような電極物質の具体例としては、Ａｕ等の金属、ＣｕＩ、インジウム－スズの複合酸化物（以下、ＩＴＯと略記。）、ＳｎＯ２、ＺｎＯ等の導電性透明材料が挙げられる。また、ＩＤＩＸＯ（Ｉｎ２Ｏ３－ＺｎＯ）等非晶質で透明導電膜を作製可能な材料を用いてもよい。陽極は、これらの電極物質を蒸着やスパッタリング等の方法により薄膜を形成させ、フォトリソグラフィー法で所望の形状パターンを形成してもよく、あるいはパターン精度をあまり必要としない場合（１００μｍ以上程度）は、上記電極物質の蒸着やスパッタリング時に所望の形状のマスクを介してパターンを形成してもよい。あるいは、有機導電性化合物のように塗布可能な物質を用いる場合には、印刷方式、コーティング方式等湿式成膜法を用いることもできる。この陽極より発光を取り出す場合には、透過率を１０％より大きくすることが望ましく、また陽極としてのシート抵抗は数百Ω／□以下が好ましい。さらに膜厚は材料にもよるが、通常は、１０～１０００ｎｍの範囲内であり、好ましくは１０～２００ｎｍの範囲内で選ばれる。 "anode"
As the anode constituting the organic EL device of the present invention, an electrode using a metal, an alloy, an electrically conductive compound and a mixture thereof having a high work function (4 eV or more) as an electrode material is preferably used. Specific examples of such an electrode substance include a conductive transparent material such as a metal such as Au, CuI, indium-tin composite oxide (hereinafter abbreviated as ITO), SnO 2 , and ZnO. Alternatively, an amorphous material such as IDIXO (In 2 O 3 —ZnO) capable of forming a transparent conductive film may be used. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a desired shape pattern may be formed by a photolithography method, or when pattern accuracy is not so high (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although depending on the material, the film thickness is usually in the range of 10 to 1000 nm, preferably in the range of 10 to 200 nm.
　《陰極》
　一方、本発明の有機ＥＬ素子を構成する陰極としては、仕事関数の小さい（４ｅＶ以下）金属（電子注入性金属と称する）、合金、電気伝導性化合物及びこれらの混合物を電極物質とするものが用いられる。このような電極物質の具体例としては、ナトリウム、ナトリウム－カリウム合金、マグネシウム、リチウム、マグネシウム／銅混合物、マグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ２Ｏ３）混合物、インジウム、リチウム／アルミニウム混合物、希土類金属等が挙げられる。これらの中で、電子注入性及び酸化等に対する耐久性の点から、第一金属である電子注入性金属とこれより仕事関数の値が大きく安定な金属である第二金属との混合物、例えば、マグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ２Ｏ３）混合物、リチウム／アルミニウム混合物、アルミニウム等が好適である。陰極はこれらの電極物質を蒸着やスパッタリング等の方法により薄膜を形成させることにより、作製することができる。また、陰極としてのシート抵抗は数百Ω／□以下が好ましく、膜厚は通常１０ｎｍ～５μｍの範囲内であり、好ましくは５０～２００ｎｍの範囲内で選ばれる。なお、発光した光を透過させるため、有機ＥＬ素子の陽極及び陰極のいずれか一方が透明又は半透明であれば発光輝度が向上し好都合である。 "cathode"
On the other hand, as the cathode constituting the organic EL device of the present invention, a cathode having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound and a mixture thereof as an electrode material. Used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al 2 O 3 ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injectable metal that is the first metal and a second metal that is a stable metal having a larger work function than this, for example, Suitable are a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al 2 O 3 ) mixture, a lithium / aluminum mixture, aluminum and the like. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually in the range of 10 nm to 5 μm, preferably in the range of 50 to 200 nm. In order to transmit the emitted light, if either one of the anode and the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved and it is convenient.
　また、陰極に上記金属を１～２０ｎｍの膜厚で形成した後に、陽極の説明で挙げた導電性透明材料をその上に形成することで、透明又は半透明の陰極を作製することができ、これを応用することで陽極と陰極の両方が透過性を有する有機ＥＬ素子を作製することができる。 Further, after forming the metal with a film thickness of 1 to 20 nm on the cathode, and forming the conductive transparent material mentioned in the description of the anode thereon, a transparent or translucent cathode can be produced. By applying this, an organic EL element in which both the anode and the cathode are transmissive can be produced.
　《支持基板》
　本発明の有機ＥＬ素子に用いることのできる支持基板（以下、基体、基板、基材、支持体等ともいう。）としては、ガラス、プラスチック等、その材質には特に限定はなく、また透明であっても不透明であってもよい。支持基板側から光を取り出す場合には、支持基板は透明であることが好ましい。好ましく用いられる透明な支持基板としては、例えば、ガラス、石英、透明樹脂フィルムを挙げることができる。リジットな基板よりもフレキシブルな基板が、高温保存安定性や色度変動を抑制する効果が大きく発現する観点から好ましく、特に好ましい支持基板は、有機ＥＬ素子にフレキシブル性を与えることが可能な可撓性を備えた樹脂フィルムであることが好ましい。 《Support substrate》
The support substrate (hereinafter also referred to as a substrate, substrate, base material, support, etc.) that can be used in the organic EL device of the present invention is not particularly limited, such as glass, plastic, etc., and is transparent. It may be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A substrate that is more flexible than a rigid substrate is preferable from the viewpoint that the effect of suppressing high-temperature storage stability and chromaticity fluctuation is greatly exhibited, and a particularly preferable support substrate is a flexible substrate that can give flexibility to an organic EL element. It is preferable that it is the resin film provided with property.
　樹脂フィルムとしては、例えば、ポリエチレンテレフタレート（ＰＥＴ）、ポリエチレンナフタレート（ＰＥＮ）等のポリエステル、ポリエチレン、ポリプロピレン、セロファン、セルロースジアセテート、セルローストリアセテート（ＴＡＣ）、セルロースアセテートブチレート、セルロースアセテートプロピオネート（ＣＡＰ）、セルロースアセテートフタレート、セルロースナイトレート等のセルロースエステル類又はそれらの誘導体、ポリ塩化ビニリデン、ポリビニルアルコール、ポリエチレンビニルアルコール、シンジオタクティックポリスチレン、ポリカーボネート、ノルボルネン樹脂、ポリメチルペンテン、ポリエーテルケトン、ポリイミド、ポリエーテルスルホン（ＰＥＳ）、ポリフェニレンスルフィド、ポリスルホン類、ポリエーテルイミド、ポリエーテルケトンイミド、ポリアミド、フッ素樹脂、ナイロン、ポリメチルメタクリレート、アクリルあるいはポリアリレート類、アートン（商品名ＪＳＲ社製）あるいはアペル（商品名三井化学社製）といったシクロオレフィン系樹脂等を挙げられる。 Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, and cellulose acetate propionate ( CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.
　樹脂フィルムの表面には、無機物、有機物の被膜又はその両者のハイブリッド被膜が形成されていてもよく、ＪＩＳ　Ｋ　７１２９－１９９２に準拠した方法で測定された、水蒸気透過度（２５±０．５℃、相対湿度（９０±２）％ＲＨ）が０．０１ｇ／（ｍ２・２４ｈ・ａｔｍ）以下のバリア性フィルムであることが好ましく、さらには、ＪＩＳ　Ｋ　７１２６－１９８７に準拠した方法で測定した酸素透過度が、１×１０－３ｃｍ３／（ｍ２・２４ｈ・ａｔｍ）以下、水蒸気透過度が１×１０－３ｇ／（ｍ２・２４ｈ・ａｔｍ）以下の高バリア性フィルムであることが好ましく、前記の水蒸気透過度が１×１０－５ｇ／（ｍ２・２４ｈ・ａｔｍ）以下であることが、更に好ましい。 The surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and the water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / (m 2 · 24 h · atm) or less, and further measured by a method according to JIS K 7126-1987. It is a high barrier film having an oxygen permeability of 1 × 10 −3 cm 3 / (m 2 · 24 h · atm) or less and a water vapor permeability of 1 × 10 −3 g / (m 2 · 24 h · atm) or less. The water vapor permeability is more preferably 1 × 10 −5 g / (m 2 · 24 h · atm) or less.
　ガスバリアー層を形成する材料としては、水分や酸素等の有機ＥＬ素子の劣化を招く因子の浸入を抑制する機能を有する材料であればよく、例えば、酸化珪素、二酸化珪素、窒化珪素等を用いることができる。さらに該膜の脆弱性を改良するために、これら無機層と有機材料からなる層の積層構造を持たせることがより好ましい。無機層と有機機能層の積層順については特に制限はないが、両者を交互に複数回積層させることが好ましい。 The material for forming the gas barrier layer may be any material that has a function of suppressing the intrusion of factors that cause deterioration of the organic EL element such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like is used. be able to. In order to further improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and layers made of organic materials. Although there is no restriction | limiting in particular about the lamination order of an inorganic layer and an organic functional layer, It is preferable to laminate | stack both alternately several times.
　ガスバリアー層の形成方法については、特に限定はなく、例えば、真空蒸着法、スパッタリング法、反応性スパッタリング法、分子線エピタキシー法、クラスタ－イオンビーム法、イオンプレーティング法、プラズマ重合法、大気圧プラズマ重合法、プラズマＣＶＤ法（ＣＶＤ：Ｃｈｅｍｉｃａｌ　Ｖａｐｏｒ　Ｄｅｐｏｓｉｔｉｏｎ）、レーザーＣＶＤ法、熱ＣＶＤ法、コーティング法等を用いることができるが、特開２００４－６８１４３号公報に記載されているような大気圧プラズマ重合法によるものが特に好ましい。 The method for forming the gas barrier layer is not particularly limited. For example, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure A plasma polymerization method, a plasma CVD method (CVD: Chemical Vapor Deposition), a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma as described in JP-A-2004-68143. A polymerization method is particularly preferred.
　不透明な支持基板としては、例えば、アルミ、ステンレス等の金属板、フィルムや不透明樹脂基板、セラミック製の基板等が挙げられる。 Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.
　本発明の有機ＥＬ素子において、発光の室温における外部取り出し効率は、１％以上であることが好ましく、より好ましくは５％以上である。 In the organic EL device of the present invention, the external extraction efficiency of light emission at room temperature is preferably 1% or more, more preferably 5% or more.
　ここで、外部取り出し量子効率（％）＝有機ＥＬ素子外部に発光した光子数／有機ＥＬ素子に流した電子数×１００である。 Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.
　《封止》
　本発明の有機ＥＬ素子に適用可能な封止手段としては、例えば、封止部材と電極、支持基板とを封止接着剤で接着する方法を挙げることができる。 <Sealing>
As a sealing means applicable to the organic EL element of the present invention, for example, a method of adhering a sealing member, an electrode, and a support substrate with a sealing adhesive can be mentioned.
　封止部材としては、有機ＥＬ素子の表示領域を覆うように配置されておればよく、凹板状でも平板状でもよい。また透明性、電気絶縁性は特に問わない。 The sealing member may be disposed so as to cover the display area of the organic EL element, and may be a concave plate shape or a flat plate shape. Further, transparency and electrical insulation are not particularly limited.
　具体的には、ガラス板、ポリマー板／フィルムの複合材料、金属板／フィルムの複合材料等が挙げられる。ガラス板としては、特に、ソーダ石灰ガラス、バリウム・ストロンチウム含有ガラス、鉛ガラス、アルミノケイ酸ガラス、ホウケイ酸ガラス、バリウムホウケイ酸ガラス、石英等を挙げることができる。また、ポリマー板を構成する材料としては、ポリカーボネート、アクリル、ポリエチレンテレフタレート、ポリエーテルサルファイド、ポリサルフォン等を挙げることができる。金属板を構成する材料としては、ステンレス、鉄、銅、アルミニウム、マグネシウム、ニッケル、亜鉛、クロム、チタン、モリブテン、シリコーン、ゲルマニウム及びタンタルからなる群から選ばれる一種以上の金属又は合金が挙げられる。 Specific examples include a glass plate, a polymer plate / film composite material, and a metal plate / film composite material. Examples of the glass plate include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the material constituting the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the material constituting the metal plate include one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicone, germanium, and tantalum.
　本発明においては、封止部材として、有機ＥＬ素子を薄膜化できるということからポリマーフィルム、金属フィルムを好ましく使用することができる。さらには、ポリマーフィルムは、ＪＩＳ　Ｋ　７１２６－１９８７に準拠した方法で測定された酸素透過度が、１×１０－３ｃｍ３／（ｍ２・２４ｈ・ａｔｍ）以下、ＪＩＳ　Ｋ　７１２９－１９９２に準拠した方法で測定された水蒸気透過度（２５±０．５℃、相対湿度（９０±２）％ＲＨ）が１×１０－３ｇ／（ｍ２・２４ｈ）以下のものであることが好ましい。 In the present invention, as the sealing member, a polymer film and a metal film can be preferably used because the organic EL element can be thinned. Furthermore, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 −3 cm 3 / (m 2 · 24 h · atm) or less, and conforms to JIS K 7129-1992. The water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured by the above method is preferably 1 × 10 −3 g / (m 2 · 24 h) or less.
　封止部材を凹状に加工するのは、サンドブラスト加工、化学エッチング加工等が使われる。 For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.
　封止接着剤としては、具体的には、アクリル酸系オリゴマー、メタクリル酸系オリゴマーの反応性ビニル基を有する光硬化及び熱硬化型接着剤、２－シアノアクリル酸エステル等の湿気硬化型等の接着剤を挙げることができる。また、エポキシ系等の熱及び化学硬化型（二液混合）を挙げることができる。また、ホットメルト型のポリアミド、ポリエステル、ポリオレフィンを挙げることができる。また、カチオン硬化タイプの紫外線硬化型エポキシ樹脂接着剤を挙げることができる。 Specific examples of the sealing adhesive include photo-curing and thermosetting adhesives having a reactive vinyl group of acrylic acid-based oligomers and methacrylic acid-based oligomers, and moisture-curing types such as 2-cyanoacrylic acid esters. Mention may be made of adhesives. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.
　なお、有機ＥＬ素子が熱処理により劣化する場合があるので、室温から８０℃までの温度範囲内で接着硬化できるものが好ましい。また、接着剤中に乾燥剤を分散させておいてもよい。封止部分への接着剤の塗布は市販のディスペンサを使ってもよいし、スクリーン印刷のように印刷してもよい。 In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened within the temperature range from room temperature to 80 degreeC is preferable. Further, a desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.
　また、有機機能層を挟み支持基板と対向する側の電極の外側に該電極と有機機能層を被覆し、支持基板と接する形で無機物、有機物の層を形成し封止膜とすることも好適にできる。この場合、該膜を形成する材料としては、水分や酸素等素子の劣化をもたらすものの浸入を抑制する機能を有する材料であればよく、例えば、酸化珪素、二酸化珪素、窒化珪素等を用いることができる。さらに該膜の脆弱性を改良するために、これら無機層と有機材料からなる層の積層構造を持たせることが好ましい。これらの膜の形成方法については、特に限定はなく、例えば真空蒸着法、スパッタリング法、反応性スパッタリング法、分子線エピタキシー法、クラスタ－イオンビーム法、イオンプレーティング法、プラズマ重合法、大気圧プラズマ重合法、プラズマＣＶＤ法、レーザーＣＶＤ法、熱ＣＶＤ法、コーティング法等を用いることができる。 It is also preferable to cover the electrode and the organic functional layer on the outer side of the electrode facing the support substrate with the organic functional layer in between, and form an inorganic or organic layer in contact with the support substrate to form a sealing film Can be. In this case, the material for forming the film may be a material having a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can. Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.
　封止部材と有機ＥＬ素子の表示領域との間隙には、気相及び液相を形成することを目的として、窒素、アルゴン等の不活性気体やフッ化炭化水素、シリコンオイルのような不活性液体を注入することが好ましい。また真空とすることも可能である。また、内部に吸湿性化合物を封入することもできる。 In order to form a gas phase and a liquid phase in the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, an inert gas such as fluorinated hydrocarbon or silicon oil is used. It is preferable to inject a liquid. A vacuum is also possible. Moreover, a hygroscopic compound can also be enclosed inside.
　吸湿性化合物としては、例えば、金属酸化物（例えば、酸化ナトリウム、酸化カリウム、酸化カルシウム、酸化バリウム、酸化マグネシウム、酸化アルミニウム等）、硫酸塩（例えば、硫酸ナトリウム、硫酸カルシウム、硫酸マグネシウム、硫酸コバルト等）、金属ハロゲン化物（例えば、塩化カルシウム、塩化マグネシウム、フッ化セシウム、フッ化タンタル、臭化セリウム、臭化マグネシウム、沃化バリウム、沃化マグネシウム等）、過塩素酸類（例えば、過塩素酸バリウム、過塩素酸マグネシウム等）等が挙げられ、硫酸塩、金属ハロゲン化物及び過塩素酸類においては無水塩が好適に用いられる。 Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, and the like), and anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.
　封止にはケーシングタイプの封止（缶封止）と密着タイプの封止（固体封止）があるが、薄型化の観点からは固体封止が好ましい。また、可撓性の有機ＥＬ素子を作製する場合は、封止部材にも可撓性が求められるため、固体封止が好ましい。 Sealing includes casing type sealing (can sealing) and close contact type sealing (solid sealing), but solid sealing is preferable from the viewpoint of thinning. Moreover, when producing a flexible organic EL element, since sealing is also required for the sealing member, solid sealing is preferable.
　以下に、固体封止を行う場合の好ましい態様を説明する。 In the following, a preferred embodiment when performing solid sealing will be described.
　本発明に係る封止用接着剤には、熱硬化接着剤や紫外線硬化樹脂などを用いることができるが、好ましくはエポキシ系樹脂、アクリル系樹脂、シリコーン樹脂など熱硬化接着剤、より好ましくは耐湿性、耐水性に優れ、硬化時の収縮が少ないエポキシ系熱硬化型接着性樹脂である。 As the sealing adhesive according to the present invention, a thermosetting adhesive, an ultraviolet curable resin, or the like can be used, but preferably a thermosetting adhesive such as an epoxy resin, an acrylic resin, or a silicone resin, more preferably moisture resistant. It is an epoxy thermosetting adhesive resin that is excellent in water resistance and water resistance and has little shrinkage during curing.
　本発明に係る封止用接着剤の含水率は、３００ｐｐｍ以下であることが好ましく、０．０１～２００ｐｐｍであることがより好ましく、０．０１～１００ｐｐｍであることが最も好ましい。 The water content of the sealing adhesive according to the present invention is preferably 300 ppm or less, more preferably 0.01 to 200 ppm, and most preferably 0.01 to 100 ppm.
　本発明でいう含水率は、いかなる方法により測定しても構わないが、例えば、容量法水分計（カールフィッシャ－）、赤外水分計、マイクロ波透過型水分計、加熱乾燥重量法、ＧＣ／ＭＳ、ＩＲ、ＤＳＣ（示差走査熱量計）、ＴＤＳ（昇温脱離分析）が挙げられる。また、精密水分計ＡＶＭ－３０００型（オムニテック社製）等を用い、水分の蒸発によって生じる圧力上昇から水分を測定でき、フィルムまた固形フィルム等の水分率の測定を行うことができる。 The moisture content in the present invention may be measured by any method. For example, a volumetric moisture meter (Karl Fischer), an infrared moisture meter, a microwave transmission moisture meter, a heat-dry weight method, a GC / MS, IR, DSC (Differential Scanning Calorimeter), TDS (Temperature Desorption Analysis). Further, using a precision moisture meter AVM-3000 (Omnitech) or the like, moisture can be measured from a pressure increase caused by evaporation of moisture, and moisture content of a film or a solid film can be measured.
　本発明おいて、封止用接着剤の含水率は、例えば、露点温度が－８０℃以下、酸素濃度０．８ｐｐｍの窒素雰囲気下に置き時間を変化させることで調整することができる。また、１００Ｐａ以下の真空状態で置き時間を変化させて乾燥させることもできる。また、封止用接着材は接着剤のみで乾燥させることもできるが、封止部材へ予め配置し乾燥させることもできる。 In the present invention, the moisture content of the sealing adhesive can be adjusted by, for example, placing it in a nitrogen atmosphere with a dew point temperature of −80 ° C. or lower and an oxygen concentration of 0.8 ppm, and changing the time. Further, it can be dried in a vacuum state of 100 Pa or less while changing the time. Further, the sealing adhesive can be dried only with an adhesive, but can also be placed in advance on the sealing member and dried.
　密着封止（固体封止方式）を行う場合、封止部材としては、例えば、５０μｍ厚のＰＥＴ（ポリエチレンテレフタレート）フィルムにアルミ箔（３０μｍ厚）をラミネートしたものを用いることができる。これを封止部材として、アルミニウム面にディスペンサを使用して均一に塗布し、封止用接着剤を予め配置しておき、樹脂基板と封止部材を位置合わせ後、両者を圧着して（０．１～３ＭＰａ）、温度８０～１８０℃で密着・接合（接着）して、密着封止（固体封止）することができる。 When close sealing (solid sealing method) is performed, as the sealing member, for example, a 50 μm thick PET (polyethylene terephthalate) film laminated with an aluminum foil (30 μm thick) can be used. Using this as a sealing member, it was uniformly applied to the aluminum surface using a dispenser, a sealing adhesive was placed in advance, the resin substrate and the sealing member were aligned, and both were crimped (0 0.1-3 MPa) and at a temperature of 80-180 ° C., it can be tightly bonded (bonded) to achieve close sealing (solid sealing).
　接着剤の種類や量、そして面積等によって加熱また圧着時間は変化するが、０．１～３ＭＰａの範囲内の圧力で仮接着、また８０～１８０℃の範囲内の温度で、熱硬化時間は５秒～１０分間の範囲内で選べばよい。 The heating or pressure bonding time varies depending on the type, amount, and area of the adhesive, but temporary bonding is performed at a pressure within the range of 0.1 to 3 MPa, and the thermosetting time is at a temperature within the range of 80 to 180 ° C. You can select from 5 seconds to 10 minutes.
　加熱した圧着ローラーを用いると圧着（仮接着）と加熱が同時にでき、且つ内部の空隙も同時に排除でき好ましい。 It is preferable to use a heated pressure roller since pressure bonding (temporary bonding) and heating can be performed simultaneously, and internal voids can be eliminated at the same time.
　また、接着層の形成方法としては、材料に応じて、ディスペンサを用い、ローラーコート、スピンコート、スクリーン印刷法、スプレーコートなどのコーティング法、印刷法を用いることができる。 Further, as a method for forming the adhesive layer, depending on the material, a coating method such as roller coating, spin coating, screen printing, spray coating, or the like can be used using a dispenser.
　固体封止は以上のように封止部材と有機ＥＬ素子基板との間に空間がなく硬化した樹脂で覆う形態である。 As described above, solid sealing is a form in which there is no space between the sealing member and the organic EL element substrate and the resin is covered with a cured resin.
　封止部材としては、ステンレス、アルミニウム、マグネシウム合金等の金属、ポリエチレンテレフタレート、ポリカーボネート、ポリスチレン、ナイロン、ポリ塩化ビニル等のプラスチック、及びこれらの複合物、ガラス等が挙げられ、必要に応じて、特に樹脂フィルムの場合には、樹脂基板と同様、アルミニウム、酸化アルミニウム、酸化ケイ素、窒化ケイ素等のガスバリアー層を積層したものを用いることができる。 Examples of the sealing member include metals such as stainless steel, aluminum, and magnesium alloys, polyethylene terephthalate, polycarbonate, polystyrene, nylon, plastics such as polyvinyl chloride, and composites thereof, glass, and the like. In the case of a resin film, a laminate of gas barrier layers such as aluminum, aluminum oxide, silicon oxide, and silicon nitride can be used in the same manner as the resin substrate.
　ガスバリアー層は、封止部材成形前に封止部材の両面若しくは片面にスパッタリング、蒸着等により形成することもできるし、封止後に封止部材の両面若しくは片面に同様な方法で形成してもよい。これについても、酸素透過度が１×１０－３ｍｌ／（ｍ２・２４ｈ・ａｔｍ）以下、水蒸気透過度（２５±０．５℃、相対湿度（９０±２）％ＲＨ）が、１×１０－３ｇ／（ｍ２・２４ｈ）以下のものであることが好ましい。 The gas barrier layer can be formed by sputtering, vapor deposition or the like on both surfaces or one surface of the sealing member before molding the sealing member, or can be formed on both surfaces or one surface of the sealing member by the same method after sealing. Good. Also in this case, the oxygen permeability is 1 × 10 −3 ml / (m 2 · 24 h · atm) or less, the water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) is 1 × It is preferably 10 −3 g / (m 2 · 24 h) or less.
　封止部材としては、アルミニウム等の金属箔をラミネートしたフィルム等でも良い。金属箔の片面にポリマーフィルムを積層する方法としては、一般に使用されているラミネート機を使用することができる。接着剤としてはポリウレタン系、ポリエステル系、エポキシ系、アクリル系等の接着剤を用いることができる。必要に応じて硬化剤を併用してもよい。ホットメルトラミネーション法やエクストルージョンラミネート法及び共押出しラミネーション法も使用できるがドライラミネート方式が好ましい。 The sealing member may be a film laminated with a metal foil such as aluminum. As a method for laminating the polymer film on one side of the metal foil, a generally used laminating machine can be used. As the adhesive, polyurethane-based, polyester-based, epoxy-based, acrylic-based adhesives and the like can be used. You may use a hardening | curing agent together as needed. A hot melt lamination method, an extrusion lamination method and a coextrusion lamination method can also be used, but a dry lamination method is preferred.
　また、金属箔をスパッタや蒸着等で形成し、導電性ペースト等の流動性電極材料から形成する場合は、逆にポリマーフィルムを基材としてこれに金属箔を成膜する方法で作成してもよい。 In addition, when the metal foil is formed by sputtering or vapor deposition and is formed from a fluid electrode material such as a conductive paste, it may be created by a method of forming a metal foil on a polymer film as a base. Good.
　《保護膜、保護板》
　有機機能層を挟み支持基板と対向する側の封止膜、あるいは封止用フィルムの外側に、有機ＥＬ素子の機械的強度を高めるため、保護膜あるいは保護板を設けてもよい。特に、封止が封止膜により行われている場合には、その機械的強度は必ずしも高くないため、このような保護膜、保護板を設けることが好ましい。これに使用することができる材料としては、前記封止に用いたのと同様なガラス板、ポリマー板・フィルム、金属板・フィルム等を用いることができるが、軽量かつ薄膜化ということからポリマーフィルムを用いることが好ましい。 《Protective film, protective plate》
In order to increase the mechanical strength of the organic EL element, a protective film or a protective plate may be provided outside the sealing film on the side facing the support substrate with the organic functional layer interposed therebetween or on the outer side of the sealing film. In particular, when sealing is performed with a sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used, but the polymer film is light and thin. Is preferably used.
　本発明において、可撓性支持基板から陽極との間、あるいは可撓性支持基板から光出射側の何れかの場所に光取出し部材を有することが好ましい。 In the present invention, it is preferable to have a light extraction member between the flexible support substrate and the anode or at any location on the light emission side from the flexible support substrate.
　光取出し部材としては、プリズムシートやレンズシート及び拡散シートが挙げられる。また、全反射を起こす界面もしくはいずれかの媒質中に導入される回折格子や拡散構造等が挙げられる。 Examples of the light extraction member include a prism sheet, a lens sheet, and a diffusion sheet. Further, a diffraction grating or a diffusion structure introduced into an interface or any medium that causes total reflection can be used.
　通常、基板から光を放射するような有機エレクトロルミネッセンス素子においては、発光層から放射された光の一部が基板と空気との界面において全反射を起こし、光を損失するという問題が発生する。この問題を解決するために、基板の表面にプリズムやレンズ状の加工を施す、もしくは基板の表面にプリズムシートやレンズシート及び拡散シートを貼り付けることにより、全反射を抑制して光の取り出し効率を向上させる。 Usually, in an organic electroluminescence element that emits light from a substrate, a part of the light emitted from the light emitting layer causes total reflection at the interface between the substrate and air, causing a problem of loss of light. In order to solve this problem, prismatic or lens-like processing is applied to the surface of the substrate, or prism sheets, lens sheets, and diffusion sheets are attached to the surface of the substrate, thereby suppressing total reflection and light extraction efficiency. To improve.
　また、光取り出し効率を高めるためには、全反射を起こす界面もしくはいずれかの媒質中に回折格子を導入する方法や拡散構造を導入する方法が知られている。 Also, in order to increase the light extraction efficiency, a method of introducing a diffraction grating or a method of introducing a diffusion structure in an interface or any medium that causes total reflection is known.
　《有機ＥＬ素子の製造方法》
　本発明の有機ＥＬ素子の製造方法の一例として、陽極／正孔注入層／正孔輸送層／発光層／電子輸送層／電子注入層／陰極からなる有機ＥＬ素子の製造方法を説明する。 << Method for Manufacturing Organic EL Element >>
As an example of the method for producing an organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.
　はじめに、適当な基体上に所望の電極物質、例えば、陽極用物質からなる薄膜を１μｍ以下、好ましくは１０～２００ｎｍの膜厚になるように、蒸着やスパッタリング等の薄膜形成方法により形成させて、陽極を作製する。 First, a desired electrode material, for example, a thin film made of an anode material is formed on a suitable substrate by a thin film forming method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably 10 to 200 nm. An anode is produced.
　次に、この上に有機ＥＬ素子材料である正孔注入層、正孔輸送層、発光層、電子輸送層、電子注入層の有機機能層（有機化合物薄膜）を形成させる。 Next, an organic functional layer (organic compound thin film) of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer, which are organic EL element materials, is formed thereon.
　有機機能層を形成する工程は、主に、
　（ｉ）その有機機能層を構成する各材料を調合して調製した塗布液を、支持基板の陽極上に塗布及び積層する塗布工程と、
　（ii）塗布及び積層して形成した塗膜を、乾燥させる乾燥工程と、
　で構成される。 The process of forming the organic functional layer mainly includes
(I) a coating step in which the coating liquid prepared by preparing each material constituting the organic functional layer is coated and laminated on the anode of the support substrate;
(Ii) a drying step of drying the coating film formed by applying and laminating;
Consists of.
　（ｉ）の塗布工程における各有機機能層の形成方法として、ウェットプロセス（例えば、スピンコート法、キャスト法、ダイコート法、ブレードコート法、ローラーコート法、インクジェット法、印刷法、スプレーコート法、カーテンコート法、ＬＢ法（ラングミュア・ブロジェット（Ｌａｎｇｍｕｉｒ　Ｂｌｏｄｇｅｔｔ法）等を挙げることができる。）を用いることができ、本発明の有機エレクトロルミネッセンス素子の製造方法においては、少なくとも量子ドットを含有する発光層を塗布方式で形成し、該発光層の形成用塗布液が、沸点が１００～１５０℃の範囲内にある溶媒を含有する形態が好ましい。 As a method for forming each organic functional layer in the coating step (i), a wet process (for example, spin coating method, casting method, die coating method, blade coating method, roller coating method, ink jet method, printing method, spray coating method, curtain) In the method for producing an organic electroluminescent device of the present invention, a light emitting layer containing at least quantum dots can be used such as a coating method and an LB method (Langmuir Brodgett method can be used). In a preferred embodiment, the light emitting layer forming coating solution contains a solvent having a boiling point in the range of 100 to 150 ° C.
　発光層以外の有機機能層の形成においても、均質な膜が得られやすく、かつピンホールが生成しにくい等の点から、本発明においてはウェットプロセスが好ましく、中でも、スピンコート法、キャスト法、ダイコート法、ブレードコート法、ローラーコート法、インクジェット法等の塗布法による成膜が好ましい。 In the formation of the organic functional layer other than the light emitting layer, it is preferable to use a wet process in the present invention from the viewpoint that a homogeneous film is easily obtained and pinholes are difficult to be generated, among others, a spin coating method, a casting method, Film formation by a coating method such as a die coating method, a blade coating method, a roller coating method, or an ink jet method is preferable.
　本発明に係る有機ＥＬ材料を溶解又は分散するのに用いる有機溶媒としては、例えば、メチルエチルケトン、シクロヘキサノン等のケトン類、酢酸エチル等の脂肪酸エステル類、ジクロロベンゼン等のハロゲン化炭化水素類、トルエン、キシレン、メシチレン、シクロヘキシルベンゼン等の芳香族炭化水素類、シクロヘキサン、デカリン、ドデカン等の脂肪族炭化水素類、ジメチルホルムアミド（ＤＭＦ）、ジメチルスルホキシド（ＤＭＳＯ）等の有機溶媒を用いることができ、その中でも沸点が１００～１５０℃の範囲内にある溶媒を用いることが好ましい。また、分散方法としては、超音波、高剪断力分散やメディア分散等の分散方法を適宜選択して適用することができる。 Examples of the organic solvent used for dissolving or dispersing the organic EL material according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, Aromatic hydrocarbons such as xylene, mesitylene, and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) can be used. It is preferable to use a solvent having a boiling point in the range of 100 to 150 ° C. In addition, as a dispersion method, a dispersion method such as ultrasonic wave, high shear force dispersion or media dispersion can be appropriately selected and applied.
　また、本発明に係る有機ＥＬ材料を溶解又は分散して塗布液を調製する調液工程や、基材上に塗布液を塗布するまでの塗布工程は、不活性ガス雰囲気下であることが好ましいが、使用素材により不活性ガス雰囲気下で行わなくとも有機ＥＬ素子性能を落とさずに成膜できるため、必ずしも全ての工程を不活性ガス雰囲気下で行わなくても良い場合がある。この様な対応をとることにより、製造コストを抑えることができより好ましい。 Moreover, it is preferable that the liquid preparation process which melt | dissolves or disperse | distributes the organic EL material which concerns on this invention, and the coating process until it applies a coating liquid on a base material are in inert gas atmosphere. However, since it is possible to form a film without degrading the performance of the organic EL element even if it is not carried out in an inert gas atmosphere depending on the material used, there are cases where not all the steps are necessarily carried out in an inert gas atmosphere. By taking such a measure, the manufacturing cost can be suppressed, which is more preferable.
　（ii）の乾燥工程では、塗布及び積層された有機機能層塗膜の乾燥を行う。 (Ii) In the drying step, the coated and laminated organic functional layer coating film is dried.
　ここでいう乾燥とは、塗布直後の塗膜の溶媒含有量を１００質量％とした場合に、０．２質量％以下まで低減されることを指す。 The term “drying” as used herein means that the content is reduced to 0.2% by mass or less when the solvent content of the coating film immediately after coating is 100% by mass.
　乾燥の手段としては、一般的な乾燥手段として汎用されているものを使用でき、減圧あるいは加圧乾燥、加熱乾燥、送風乾燥、ＩＲ乾燥及び電磁波による乾燥などが挙げられる。中でも、加熱乾燥が好ましく、有機機能層塗布液の調製で用いた溶媒の中で、最も低沸点の溶媒の沸点以上の温度であり、有機機能層材料のガラス転移温度Ｔｇの中で最も低Ｔｇである材料の（Ｔｇ＋２０）℃より低い温度で保持することが最も好ましい。本発明において、より具体的には８０～１５０℃の温度範囲に保持して乾燥することが好ましく、１００～１３０℃の温度範囲に保持して乾燥することがより好ましい。 As the drying means, those commonly used as general drying means can be used, and examples thereof include reduced pressure or pressure drying, heat drying, air drying, IR drying, and electromagnetic wave drying. Among these, heat drying is preferable, and among the solvents used in the preparation of the organic functional layer coating solution, the temperature is equal to or higher than the boiling point of the lowest boiling solvent, and the lowest Tg among the glass transition temperatures Tg of the organic functional layer material. It is most preferable to hold at a temperature lower than (Tg + 20) ° C. of the material. In the present invention, more specifically, drying is preferably carried out while maintaining a temperature range of 80 to 150 ° C., more preferably drying while maintaining a temperature range of 100 to 130 ° C.
　塗布及び積層した後の塗膜を乾燥させる際の雰囲気は、不活性ガス以外の気体の体積濃度が２００ｐｐｍ以下の雰囲気とすることが好ましいが、調液工程及び塗布工程と同様に、必ずしも不活性ガス雰囲気下で行わなくても良い場合がある。この場合、製造コストを抑えることができより好ましい。 The atmosphere when drying the coating film after application and lamination is preferably an atmosphere in which the volume concentration of gas other than the inert gas is 200 ppm or less, but it is not necessarily inert as in the preparation step and the application step. There is a case where it is not necessary to carry out in a gas atmosphere. In this case, the manufacturing cost can be suppressed, which is more preferable.
　不活性ガスは好ましくは窒素ガス及びアルゴンガス等の希ガスであり、製造コスト上最も好ましくは窒素ガスである。 The inert gas is preferably a rare gas such as nitrogen gas or argon gas, and most preferably nitrogen gas in terms of production cost.
　これらの有機機能層の塗布、積層及び乾燥工程は、枚葉製造方式であっても、連続したオンライン製造方式であっても良い。更に、乾燥工程は、搬送ライン上で搬送中に行っても良いが、生産性の観点からは、堆積あるいはロール状に非接触で巻き取り乾燥しても良い。 The coating, laminating and drying steps of these organic functional layers may be a single wafer manufacturing method or a continuous online manufacturing method. Furthermore, the drying step may be performed during conveyance on the conveyance line, but from the viewpoint of productivity, it may be wound up and dried in a non-contact manner in the form of a deposit or a roll.
　これらの塗膜を乾燥した後、その上に陰極用物質からなる薄膜を、１μｍ以下、好ましくは５０～２００ｎｍの範囲内の膜厚になるように、例えば、蒸着やスパッタリング等の方法により形成させ、陰極を設けることにより、所望の有機ＥＬ素子が得られる。 After these coating films are dried, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 50 to 200 nm. By providing the cathode, a desired organic EL element can be obtained.
　該加熱処理後に前記密着封止あるいは封止部材と電極、支持基板とを接着剤で接着することで有機ＥＬ素子を製造することができる。 After the heat treatment, the organic EL element can be produced by adhering the contact sealing or sealing member to the electrode and the support substrate with an adhesive.
　《用途》
　本発明の有機ＥＬ素子は、表示デバイス、ディスプレイ、各種発光光源として用いることができる。 <Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources.
　発光光源として、例えば、家庭用照明、車内照明、時計や液晶用のバックライト、看板広告、信号機、光記憶媒体の光源、電子写真複写機の光源、光通信処理機の光源、光センサーの光源、さらには表示装置を必要とする一般の家庭用電気器具等広い範囲の用途が挙げられるが、特にカラーフィルターと組み合わせた液晶表示装置のバックライト、照明用光源としての用途に有効に用いることができる。 Examples of light sources include home lighting, interior lighting, backlights for watches and liquid crystals, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, and light sources for optical sensors. Furthermore, it can be used in a wide range of applications such as general household appliances that require a display device, but it can be used effectively as a backlight of a liquid crystal display device combined with a color filter, and as a light source for illumination. it can.
　本発明の有機ＥＬ素子においては、必要に応じ成膜時にメタルマスクやインクジェットプリンティング法等でパターニングを施してもよい。パターニングする場合は、電極のみをパターニングしてもよいし、電極と発光層をパターニングしてもよいし、素子全層をパターニングしてもよく、素子の作製においては、従来公知の方法を用いることができる。 In the organic EL device of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like during film formation, if necessary. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.
　以下、実施例を挙げて本発明を具体的に説明するが、本発明はこれらに限定されるものではない。なお、実施例において「％」の表示を用いるが、特に断りがない限り「質量％」を表す。 Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.
　《有機ＥＬ素子の作製》
　下記の方法に従って、有機ＥＬ素子１～１５を作製した。 << Production of organic EL element >>
Organic EL elements 1 to 15 were produced according to the following method.
　〔有機ＥＬ素子１の作製：本発明〕
　（１．１）ガスバリアー性の可撓性フィルムの作製
　可撓性フィルムとして、ポリエチレンナフタレートフィルム（帝人デュポン社製フィルム、以下、ＰＥＮフィルムと略記する。）を用い、可撓性フィルムの第１電極を形成する面側の全面に、特開２００４－６８１４３号公報に記載の構成からなる大気圧プラズマ放電処理装置を用いて、連続して可撓性フィルム上に、ＳｉＯｘからなる無機物のガスバリアー層を厚さ５００ｎｍとなるように形成し、酸素透過度が０．００１ｍｌ／（ｍ２・ｄａｙ・ａｔｍ）以下で、水蒸気透過度が０．００１ｇ／（ｍ２・ｄａｙ・ａｔｍ）以下のガスバリアー性の可撓性フィルムを作製した。 [Preparation of Organic EL Element 1: Present Invention]
(1.1) Production of gas barrier flexible film A polyethylene naphthalate film (a film made by Teijin DuPont, hereinafter abbreviated as a PEN film) is used as the flexible film. Using an atmospheric pressure plasma discharge treatment apparatus having the configuration described in Japanese Patent Application Laid-Open No. 2004-68143, an inorganic substance composed of SiO x is continuously formed on the entire surface on the surface side on which one electrode is formed. The gas barrier layer is formed to have a thickness of 500 nm, the oxygen permeability is 0.001 ml / (m 2 · day · atm) or less, and the water vapor permeability is 0.001 g / (m 2 · day · atm) or less. A gas barrier flexible film was prepared.
　（１．２）第１電極層の形成
　上記作製したガスバリアー性の可撓性フィルム上に、厚さ１２０ｎｍのＩＴＯ（インジウム－スズの複合酸化物）膜をスパッタ法により成膜し、フォトリソグラフィー法によりパターニングを行い、第１電極層（陽極）を形成した。なお、パターンは発光面積が５０ｍｍ平方になるようなパターンとした。 (1.2) Formation of First Electrode Layer An ITO (indium-tin composite oxide) film having a thickness of 120 nm is formed by sputtering on the gas barrier flexible film produced above, and photolithography is performed. Patterning was performed by the method to form a first electrode layer (anode). The pattern was such that the light emission area was 50 mm square.
　（１．３）正孔注入層の形成
　第１電極層をパターニングした後のＩＴＯ基板をイソプロピルアルコールで超音波洗浄し、乾燥窒素ガスで乾燥した後、ＵＶオゾン洗浄を５分間行った。このＩＴＯ基板上に、ポリ（３，４－エチレンジオキシチオフェン）－ポリスチレンスルホネート（以下、ＰＥＤＯＴ／ＰＳＳと略記、Ｂａｙｅｒ製、Ｂａｙｔｒｏｎ　Ｐ　Ａｌ　４０８３）を純水で７０％に希釈した溶液を、３０００ｒｐｍ、３０秒でスピンコート法により製膜した後、２００℃にて１時間乾燥し、厚さ３０ｎｍの正孔注入層を形成した。 (1.3) Formation of hole injection layer The ITO substrate after patterning the first electrode layer was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and then subjected to UV ozone cleaning for 5 minutes. A solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (hereinafter abbreviated as PEDOT / PSS, manufactured by Bayer, Baytron P Al 4083) to 70% with pure water on this ITO substrate at 3000 rpm. After forming the film by spin coating in 30 seconds, the film was dried at 200 ° C. for 1 hour to form a hole injection layer having a thickness of 30 nm.
　（１．４）正孔輸送層の形成
　この正孔注入層を形成した基板を、窒素ガス（グレードＧ１）を用いた窒素雰囲気下に移し、正孔輸送材料である下記正孔輸送材料Ａ（Ｍｗ＝８０，０００）をクロロベンゼンに０．５％の濃度で溶解した溶液を、１５００ｒｐｍ、３０秒でスピンコート法により製膜した後、１６０℃で３０分間保持して乾燥し、厚さ３０ｎｍの正孔輸送層を形成した。 (1.4) Formation of Hole Transport Layer The substrate on which this hole injection layer was formed was transferred to a nitrogen atmosphere using nitrogen gas (grade G1), and the following hole transport material A ( Mw = 80,000) dissolved in chlorobenzene at a concentration of 0.5% was formed by spin coating at 1500 rpm for 30 seconds, dried at 160 ° C. for 30 minutes, and dried to a thickness of 30 nm. A hole transport layer was formed.
Figure JPOXMLDOC01-appb-C000040
  
Figure JPOXMLDOC01-appb-C000040
  
　（１．５）発光層の形成
　次いで、下記組成の発光層組成物１を、１５００ｒｐｍ、３０秒でスピンコート法により製膜した後、１２０℃で３０分間保持して乾燥し、厚さ４０ｎｍの発光層を形成した。 (1.5) Formation of Light Emitting Layer Next, a light emitting layer composition 1 having the following composition was formed by spin coating at 1500 rpm for 30 seconds, dried at 120 ° C. for 30 minutes, and dried to a thickness of 40 nm. A light emitting layer was formed.
　〈発光層組成物１〉
　ホスト化合物：例示化合物Ｈ－５５（発光波長：４２０ｎｍ、２．９５ｅＶ、分子量：６５１、化１４に記載）　　　　　　　　　１３．９５質量部
　緑ドーパントＤＧ（発光波長：５２０ｎｍ）　　　　　　０．２５質量部
　赤ドーパントＤＲ（発光波長：６２０ｎｍ）　　　　　　０．１０質量部
　量子ドット１　コア部：ＣｄＳｅ（２ｎｍ）／シェル部ＺｎＳ（オクタデシルアミン）、平均粒子径７ｎｍ、アスペクト比＝１．２５、発光波長：４５９ｎｍ、２．７ｅＶ）　　　　　　　　　　　　　　　　　３．０質量部
　トルエン　　　　　　　　　　　　　　　　　　　　　２，０００質量部
Figure JPOXMLDOC01-appb-C000041
   <Light emitting layer composition 1>
Host compound: Exemplified compound H-55 (emission wavelength: 420 nm, 2.95 eV, molecular weight: 651, described in Chemical formula 14) 13.95 parts by mass Green dopant DG (emission wavelength: 520 nm) 0.25 parts by mass Red dopant DR ( (Emission wavelength: 620 nm) 0.10 parts by mass Quantum dot 1 Core part: CdSe (2 nm) / shell part ZnS (octadecylamine), average particle diameter 7 nm, aspect ratio = 1.25, emission wavelength: 459 nm, 2.7 eV) 3.0 parts by mass Toluene 2,000 parts by mass
Figure JPOXMLDOC01-appb-C000041
　〈量子ドット１の調製〉
　アルゴン気流下で、トリ－ｎ－オクチルホスフィンオキシド（ＴＯＰＯ）（関東化学社製）７．５ｇに、ステアリン酸（関東化学社製）２．９ｇ、ｎ－テトラデシルホスホン酸（ＡＶＯＣＡＤＯ社製）６２０ｍｇ、及び、酸化カドミニウム（和光純薬工業社製）２５０ｍｇを加え、３７０℃に加熱混合した。これを２７０℃まで自然冷却させた後、予めトリブチルホスフィン（関東化学社製）２．５ｍｌに、セレン（ＳＴＲＥＭＣＨＥＭＩＣＡＬ社製）２００ｍｇを溶解させた溶液を加え、減圧乾燥し、ＴＯＰＯで被覆されたＣｄＳｅ微粒子を得た。 <Preparation of quantum dot 1>
Under an argon stream, 7.5 g of tri-n-octylphosphine oxide (TOPO) (manufactured by Kanto Chemical Co.), 2.9 g of stearic acid (manufactured by Kanto Chemical Co., Ltd.), 620 mg of n-tetradecylphosphonic acid (manufactured by AVOCADO) Then, 250 mg of cadmium oxide (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was heated and mixed at 370 ° C. After naturally cooling this to 270 ° C., a solution in which 200 mg of selenium (manufactured by STREMCHEMICAL) was dissolved in 2.5 ml of tributylphosphine (manufactured by Kanto Chemical Co., Inc.) was added in advance, dried under reduced pressure, and CdSe coated with TOPO. Fine particles were obtained.
　次いで、得られたＣｄＳｅ微粒子に、ＴＯＰＯ１５ｇを加えて加熱し、引き続き２７０℃でトリオクチルホスフィン（シグマアルドリッチ社製）１０ｍｌにジエチルジチオカルバミン酸亜鉛（東京化成社製）１．１ｇを溶解した溶液を加え、表面にＴＯＰＯが固定された、ＣｄＳｅのナノ結晶（平均粒子径２ｎｍ）をコアとし、ＺｎＳをシェルとする量子ドット１（平均粒子径：１２ｎｍ）を調製した。なお、量子ドット１の平均粒子径及びアスペクト比は、後述の電子間力顕微鏡（ＡＦＭ）を用いた方法で測定を行った。 Next, 15 g of TOPO was added to the obtained CdSe fine particles and heated, and subsequently, a solution of 1.1 g of zinc diethyldithiocarbamate (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved in 10 ml of trioctylphosphine (manufactured by Sigma Aldrich) was added at 270 ° C. Quantum dots 1 (average particle size: 12 nm) having a core of CdSe nanocrystals (average particle size of 2 nm) and ZnS as a shell with TOPO fixed on the surface were prepared. In addition, the average particle diameter and aspect ratio of the quantum dot 1 were measured by the method using the below-mentioned electron force microscope (AFM).
　（１．６）電子輸送層の形成
　続いて、電子輸送材料である２０ｍｇの下記電子輸送材料Ｂを、４ｍｌのテトラフルオロプロパノール（ＴＦＰＯ）に溶解した溶液を、１５００ｒｐｍ、３０秒でスピンコート法により製膜した後、１２０℃で３０分間保持して乾燥し、厚さ３０ｎｍの電子輸送層を形成した。 (1.6) Formation of Electron Transport Layer Subsequently, a solution obtained by dissolving 20 mg of the following electron transport material B, which is an electron transport material, in 4 ml of tetrafluoropropanol (TFPO) was spin-coated at 1500 rpm for 30 seconds. After forming the film, it was kept at 120 ° C. for 30 minutes and dried to form an electron transport layer having a thickness of 30 nm.
　なお、下記電子輸送材料Ｂは、特開２０１０-２３５５７５号公報を参考として合成することができる。 The following electron transport material B can be synthesized with reference to Japanese Patent Application Laid-Open No. 2010-235575.
Figure JPOXMLDOC01-appb-C000042
  
Figure JPOXMLDOC01-appb-C000042
  
　（１．７）電子注入層、陰極の形成
　続いて、基板を大気雰囲気に曝露することなく真空蒸着装置へ取り付けた。また、モリブデン製抵抗加熱ボートにフッ化ナトリウム及びフッ化カリウムを入れたものを真空蒸着装置に取り付け、真空槽を４×１０－５Ｐａまで減圧した後、前記ボートに通電して加熱してフッ化ナトリウムを０．０２ｎｍ／秒で前記電子輸送層上に厚さ１ｎｍの薄膜を形成し、続けて同様にフッ化カリウムを０．０２ｎｍ／秒でフッ化ナトリウム上に厚さ１．５ｎｍの電子注入層を形成した。引き続き、アルミニウム薄膜を厚さ１００ｎｍで蒸着して陰極を形成した。 (1.7) Formation of electron injection layer and cathode Subsequently, the substrate was attached to a vacuum deposition apparatus without being exposed to the atmospheric air. In addition, a molybdenum resistance heating boat containing sodium fluoride and potassium fluoride is attached to a vacuum evaporation system, and the vacuum chamber is depressurized to 4 × 10 −5 Pa, and then the boat is energized and heated. A thin film having a thickness of 1 nm is formed on the electron transport layer at a rate of 0.02 nm / second with sodium fluoride, and then an electron with a thickness of 1.5 nm on the sodium fluoride at a rate of 0.02 nm / second in the same manner. An injection layer was formed. Subsequently, an aluminum thin film was deposited with a thickness of 100 nm to form a cathode.
　（１．８）封止及び有機ＥＬ素子の作製
　引き続き、市販のローラーラミネート装置を用いて封止部材を接着し、本発明の有機ＥＬ素子１を製作した。 (1.8) Sealing and Production of Organic EL Element Subsequently, a sealing member was adhered using a commercially available roller laminating apparatus to produce the organic EL element 1 of the present invention.
　なお、封止部材としては、可撓性の厚さ３０μｍのアルミニウム箔（東洋アルミニウム株式会社製）に、ポリエチレンテレフタレート（ＰＥＴ）フィルム（１２μｍ厚）をドライラミネーション用の接着剤（２液反応型のウレタン系接着剤）を用いラミネートした（接着剤層の厚さ１．５μｍ）ものを用いた。 As the sealing member, a flexible aluminum foil (manufactured by Toyo Aluminum Co., Ltd.), a polyethylene terephthalate (PET) film (12 μm thick) and an adhesive for dry lamination (two-component reactive type) A laminate (a thickness of the adhesive layer of 1.5 μm) using a urethane adhesive) was used.
　封止用接着剤として熱硬化性接着剤を、ディスペンサを使用してアルミ箔の接着面（つや面）に沿って厚さ２０μｍで均一に塗布した。これを１００Ｐａ以下の真空下で１２時間乾燥させた。さらに露点温度が－８０℃以下、酸素濃度０．８ｐｐｍの窒素雰囲気下へ移動し、１２時間以上乾燥させ、封止用接着剤の含水率を１００ｐｐｍ以下となるように調整した。 A thermosetting adhesive as a sealing adhesive was uniformly applied at a thickness of 20 μm along the adhesive surface (glossy surface) of the aluminum foil using a dispenser. This was dried under a vacuum of 100 Pa or less for 12 hours. Furthermore, it moved to a nitrogen atmosphere with a dew point temperature of −80 ° C. or lower and an oxygen concentration of 0.8 ppm, dried for 12 hours or longer, and adjusted the water content of the sealing adhesive to 100 ppm or lower.
　熱硬化接着剤としては、下記の（Ａ）～（Ｃ）を混合したエポキシ系接着剤を用いた。 As the thermosetting adhesive, an epoxy adhesive mixed with the following (A) to (C) was used.
　（Ａ）ビスフェノールＡジグリシジルエーテル（ＤＧＥＢＡ）
　（Ｂ）ジシアンジアミド（ＤＩＣＹ）
　（Ｃ）エポキシアダクト系硬化促進剤
　以上のようにして、図１に記載の形態になるように、封止基板を取り出し電極及び電極リードの接合部を覆うようにして密着及び配置して、圧着ローラーを用いて厚着条件として圧着ローラー温度１２０℃、圧力０．５ＭＰａ、装置速度０．３ｍ／ｍｉｎで密着封止して、発光層に量子ドットを含有する本発明の有機ＥＬ素子１を作製した。 (A) Bisphenol A diglycidyl ether (DGEBA)
(B) Dicyandiamide (DICY)
(C) Epoxy adduct-based curing accelerator As described above, the sealing substrate is taken out so as to cover the bonding portion between the electrode and the electrode lead, and crimped so as to be in the form shown in FIG. The organic EL device 1 of the present invention containing quantum dots in the light-emitting layer was produced by tightly sealing with a roller using a pressure roller temperature of 120 ° C., a pressure of 0.5 MPa, and an apparatus speed of 0.3 m / min. .
　〔有機ＥＬ素子２～１３の作製：本発明〕
　上記有機ＥＬ素子１の作製において、発光層で用いたホスト化合物として、例示化合物Ｈ－５５を、表１に記載の各ホスト化合物に変更した以外は同様にして、有機ＥＬ素子２～１３を作製した。 [Production of Organic EL Elements 2 to 13: Present Invention]
In the production of the organic EL device 1, organic EL devices 2 to 13 were produced in the same manner except that Exemplified Compound H-55 was changed to each host compound shown in Table 1 as the host compound used in the light emitting layer. did.
　〔有機ＥＬ素子１４～１６の作製：比較例〕
　上記有機ＥＬ素子１の作製において、発光層で用いたホスト化合物として、例示化合物Ｈ－５５を、下記比較化合物１～３にそれぞれ変更した以外は同様にして、比較例である有機ＥＬ素子１４～１６を作製した。 [Production of Organic EL Elements 14 to 16: Comparative Example]
In the production of the organic EL element 1, the organic compound EL elements 14 to 14 were compared in the same manner except that the exemplified compound H-55 was changed to the following comparative compounds 1 to 3 as host compounds used in the light emitting layer. 16 was produced.
Figure JPOXMLDOC01-appb-C000043
  
Figure JPOXMLDOC01-appb-C000043
  
　《有機ＥＬ素子の評価》
　上記作製した有機ＥＬ素子１～１６について、下記の各評価を行った。 << Evaluation of organic EL elements >>
Each of the organic EL elements 1 to 16 produced above was evaluated as follows.
　（１）発光効率の測定
　上記作製した各有機ＥＬ素子を、室温（約２３℃）で、２．５ｍＡ／ｃｍ２の定電流条件下で発光させ、発光開始直後の発光輝度Ｌを、分光放射輝度計ＣＳ－２０００（コニカミノルタ社製）を用いて測定した。 (1) Measurement of luminous efficiency Each of the organic EL devices prepared above was allowed to emit light at room temperature (about 23 ° C.) under a constant current of 2.5 mA / cm 2 , and the emission luminance L immediately after the start of emission was measured as spectral emission. The luminance was measured using a luminance meter CS-2000 (manufactured by Konica Minolta).
　次いで、比較例である有機ＥＬ素子１４の発光輝度を１．０とした相対発光輝度を求め、これを発光効率（外部取り出し量子効率）の尺度とした。数値が大きいほど、発光効率に優れていることを表す。 Next, a relative light emission luminance was determined with the light emission luminance of the organic EL element 14 as a comparative example being 1.0, and this was used as a measure of the light emission efficiency (external extraction quantum efficiency). It represents that it is excellent in luminous efficiency, so that a numerical value is large.
　（２）駆動電圧の測定
　各有機ＥＬ素子を、室温（約２３℃）で、２．５ｍＡ／ｃｍ２の定電流条件下で発光させた時の駆動電圧を測定した。 (2) Measurement of driving voltage The driving voltage was measured when each organic EL element was allowed to emit light at room temperature (about 23 ° C.) under a constant current condition of 2.5 mA / cm 2 .
　次いで、比較例である有機ＥＬ素子１４の駆動電圧を基準とし、それからの駆動電圧差を求めた。マイナスの数値が大きい程ほど、低電圧駆動性に優れていることを表す。 Next, the drive voltage difference was determined based on the drive voltage of the organic EL element 14 as a comparative example. The larger the negative value, the better the low voltage drivability.
　（３）素子寿命の評価
　各有機ＥＬ素子を半径が５ｃｍの金属製円柱に巻きつけ、次いで各有機ＥＬ素子を折り曲げた状態で連続駆動させ、上記分光放射輝度計ＣＳ－２０００を用いて輝度を測定し、測定した輝度が半減するまでに要する時間（ＬＴ５０）を求めた。駆動条件は、連続駆動開始時に発光輝度が４０００ｃｄ／ｍ２となる条件で電流値とした。 (3) Evaluation of element lifetime Each organic EL element is wound around a metal cylinder having a radius of 5 cm, and then continuously driven in a state where each organic EL element is bent, and brightness is measured using the spectral radiance meter CS-2000. The time (LT50) required until the measured luminance was reduced by half was determined. The driving condition was set to a current value under the condition that the emission luminance was 4000 cd / m 2 at the start of continuous driving.
　次いで、比較例である有機ＥＬ素子１４のＬＴ５０を１．０とする相対値を求め、これを素子寿命（連続駆動安定性）の尺度とした。数値が大きいほど、連続駆動安定性に優れ、素子寿命が長いことを表す。 Next, a relative value with an LT50 of 1.0 of the organic EL element 14 as a comparative example was determined, and this was used as a measure of the element life (continuous drive stability). Larger values indicate better continuous drive stability and longer device life.
　（４）演色性の評価
　各有機ＥＬ素子を、室温（約２３～２５℃）で印加し、分光放射輝度計ＣＳ－２０００（コニカミノルタ社製）を用いて、発光輝度として１０００ｃｄ／ｍ２で発光させた状態で、上記分光放射輝度計を用いて分光分布特性を測定し、その測定結果より演色評価数を求め、平均演色評価数を導出した。 (4) Evaluation of color rendering properties Each organic EL element was applied at room temperature (about 23 to 25 ° C.), and using a spectral radiance meter CS-2000 (manufactured by Konica Minolta), the emission luminance was 1000 cd / m 2 . With the light emitted, the spectral distribution characteristics were measured using the spectral radiance meter, and the color rendering index was obtained from the measurement result, and the average color rendering index was derived.
　（５）演色性の色ずれ耐性の評価
　各有機ＥＬ素子を、連続駆動開始時からＬＴ５０まで連続的に駆動させ、上記分光放射輝度計ＣＳ－２０００を用いて輝度を測定し、測定した輝度が半減するまでに要する時間（ＬＴ５０）を求めた。 (5) Evaluation of color misregistration resistance of color rendering properties Each organic EL element was continuously driven from the start of continuous driving to LT 50, and the luminance was measured using the spectral radiance meter CS-2000. The time required to halve (LT50) was determined.
　次いで、駆動開始時とＬＴ５０到達時の色度（ＣＩＥ表色系ｘ，ｙ）を、上記分光放射輝度計により測定し、駆動開始時の色度（ｘ，ｙ）に対するＬＴ５０到達時の色度（ｘ，ｙ）の各色差（Δｘ及びΔｙ）を求め、これを色ずれ耐性の尺度とした。数値が小さほど色ずれが小さく、色度安定性に優れていることを表す。 Then, the drive start and LT 50 reaches when the chromaticity (CIE color system x, y) and measured by the spectroradiometer, the start of driving the chromaticity (x, y) for the LT 50 at arrival Each color difference (Δx and Δy) of chromaticity (x, y) was determined and used as a measure of color misregistration resistance. The smaller the numerical value, the smaller the color shift and the better the chromaticity stability.
　（６）量子ドットの粒径とアスペクト比の測定
　電子間力顕微鏡（ＡＦＭ）として、セイコーインスツルメンツ社製のＳＰＩ３８００Ｎプローブステーション及びＳＰＡ４００多機能型ユニットを使用し、約１ｃｍ角の大きさに切り取った試料（前記（１．５）発光層までを製膜したサンプルを使用）を、ピエゾスキャナー上の水平な試料台上にセットし、カンチレバーを試料表面にアプローチし、原子間力が働く領域に達したところで、ＸＹ方向にスキャンし、その際の試料の凹凸をＺ方向のピエゾの変位で捉える。ピエゾスキャナーは、ＸＹ方向に１５０μｍ、Ｚ方向に５μｍ走査可能なものを使用する。カンチレバーは、セイコーインスツルメンツ社製シリコンカンチレバーＳＩ－ＤＦ２０で、共振周波数１２０～１５０ｋＨｚ、バネ定数１２～２０Ｎ／ｍのものを用い、ＤＦＭモード（Ｄｙｎａｍｉｃ　Ｆｏｒｃｅ　Ｍｏｄｅ）で測定する。測定領域８０×８０μｍを、走査周波数０．１Ｈｚで測定した。 (6) Measurement of particle size and aspect ratio of quantum dots Samples cut into a size of about 1 cm square using an SPI3800N probe station and SPA400 multifunctional unit manufactured by Seiko Instruments Inc. as an electron force microscope (AFM) (Use the sample that has been deposited up to the (1.5) luminescent layer) was set on a horizontal sample stage on the piezo scanner, and the cantilever approached the sample surface to reach the region where the atomic force works By the way, scanning in the XY direction is performed, and the unevenness of the sample at that time is captured by the displacement of the piezo in the Z direction. A piezo scanner that can scan 150 μm in the XY direction and 5 μm in the Z direction is used. The cantilever is a silicon cantilever SI-DF20 manufactured by Seiko Instruments Inc., which has a resonance frequency of 120 to 150 kHz and a spring constant of 12 to 20 N / m, and is measured in a DFM mode (Dynamic Force Mode). A measurement area of 80 × 80 μm was measured at a scanning frequency of 0.1 Hz.
　測定の結果、いずれのサンプルでもＺｎＳシェルのサイズを含めた量子ドットの直径は５～１５ｎｍの範囲内であり、またアスペクト比（量子ドットの短径と長径の比）は１：１～１：１．５の範囲内であった。 As a result of the measurement, the diameter of the quantum dot including the size of the ZnS shell is in the range of 5 to 15 nm in any sample, and the aspect ratio (ratio of the minor axis to the major axis of the quantum dot) is 1: 1 to 1: It was within the range of 1.5.
　以上により得られた結果を、表１に示す。 Table 1 shows the results obtained as described above.
Figure JPOXMLDOC01-appb-T000044
  
Figure JPOXMLDOC01-appb-T000044
  
　表１に記載の結果より明らかなように、本発明で規定する構成からなる本発明の有機ＥＬ素子１～１２では、比較例に対し、発光輝度（発光効率）が高く、駆動電圧が低くなっており、さらには演色性や素子寿命も向上し、色度も安定していることがわかる。 As is clear from the results shown in Table 1, the organic EL elements 1 to 12 of the present invention having the configuration defined in the present invention have higher emission luminance (emission efficiency) and lower drive voltage than the comparative example. Furthermore, it can be seen that the color rendering properties and the element lifetime are improved, and the chromaticity is stable.
　以上に示した発光効率、低駆動電圧化、素子寿命、演色性及び色度安定性の評価結果より、青色発光の量子ドットを含む有機ＥＬ素子の発光効率を高め、かつ長寿命化にするためには、発光層のホスト化合物のリン光スペクトルにおける０－０遷移バンドに帰属される発光波長を特定の範囲内に制御することは有用であることが分かる。 Based on the evaluation results of the luminous efficiency, low driving voltage, element lifetime, color rendering properties and chromaticity stability shown above, to increase the luminous efficiency and extend the lifetime of organic EL elements including blue emitting quantum dots. It can be seen that it is useful to control the emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum of the host compound in the light emitting layer within a specific range.
　本発明の有機エレクトロルミネッセンス素子は、高発光効率で、長寿命で、かつ演色性及び低駆動電圧でも色度が安定した白色発光特性を備え、表示デバイス、ディスプレイ、各種発光光源として好適に利用できる。 The organic electroluminescence element of the present invention has high luminous efficiency, long life, and white light emission characteristics that are stable in chromaticity even with color rendering and low driving voltage, and can be suitably used as a display device, a display, and various light sources. .
　１　可撓性支持基板.
　２　陽極
　３　正孔注入層
　４　正孔輸送層
　５　発光層
　６　電子輸送層
　７　電子注入層
　８　陰極
　９　封止接着剤
　１０　可撓性封止部材
　１１　量子ドット発光材料
　２０　有機機能層
　１００　有機エレクトロルミネッセンス素子 1 Flexible support substrate.
DESCRIPTION OF SYMBOLS 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode 9 Sealing adhesive 10 Flexible sealing member 11 Quantum dot luminescent material 20 Organic functional layer 100 Organic electroluminescence element

Claims (11)

  1. 　少なくとも、陽極、正孔輸送層、リン光発光性化合物を含有する発光層、電子輸送層及び陰極を有する有機エレクトロルミネッセンス素子であって、
    　前記発光層が、発光波長が４１３～４７７ｎｍの範囲内にある量子ドットと、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４１３～４５９ｎｍの範囲内にあるホスト化合物とを含有することを特徴とする有機エレクトロルミネッセンス素子。     An organic electroluminescence device having at least an anode, a hole transport layer, a light emitting layer containing a phosphorescent compound, an electron transport layer and a cathode,
    The light-emitting layer contains quantum dots having an emission wavelength in the range of 413 to 477 nm and a host compound having an emission wavelength in the range of 413 to 459 nm attributed to the 0-0 transition band in the phosphorescence spectrum. An organic electroluminescence device characterized by that.
  2. 　前記量子ドットの平均粒子径が、１～２０ｎｍの範囲内であることを特徴とする請求項１に記載の有機エレクトロルミネッセンス素子。 2. The organic electroluminescence device according to claim 1, wherein an average particle size of the quantum dots is in a range of 1 to 20 nm.
  3. 　前記量子ドットのアスペクト比（長軸径／短軸径）の値が、１．０～２．０の範囲内であることを特徴とする請求項１又は請求項２に記載の有機エレクトロルミネッセンス素子。 3. The organic electroluminescence device according to claim 1, wherein the aspect ratio (major axis diameter / minor axis diameter) of the quantum dots is in the range of 1.0 to 2.0. .
  4. 　前記量子ドットが、少なくともＳｉ、Ｇｅ、ＧａＮ、ＧａＰ、ＣｄＳ、ＣｄＳｅ、ＣｄＴｅ、ＩｎＰ、ＩｎＮ、ＺｎＳ、Ｉｎ２Ｓ３、ＺｎＯ、ＣｄＯ又はこれらの混合物で構成されていることを特徴とする請求項１から請求項３までのいずれか一項に記載の有機エレクトロルミネッセンス素子。 The quantum dot is composed of at least Si, Ge, GaN, GaP, CdS, CdSe, CdTe, InP, InN, ZnS, In 2 S 3 , ZnO, CdO, or a mixture thereof. The organic electroluminescent element according to any one of claims 1 to 3.
  5. 　前記ホスト化合物の分子量が、５００～１０００の範囲内であることを特徴とする請求項１から請求項４までのいずれか一項に記載の有機エレクトロルミネッセンス素子。 The organic electroluminescence device according to any one of claims 1 to 4, wherein the host compound has a molecular weight in the range of 500 to 1,000.
  6. 　前記発光層が、前記ホスト化合物として、下記一般式（１）で表される化合物を含有することを特徴とする請求項１から請求項５までのいずれか一項に記載の有機エレクトロルミネッセンス素子。
    Figure JPOXMLDOC01-appb-C000001
      
    〔式中、Ｘは、ＮＲ′、酸素原子、硫黄原子、ＣＲ′Ｒ″、又はＳｉＲ′Ｒ″を表す。ｙ１及びｙ２は、各々ＣＲ′又は窒素原子を表す。Ｒ′及びＲ″は、各々水素原子又は置換基を表す。Ａｒ１及びＡｒ２は、各々芳香環を表し、それぞれ同一でも異なっていても良い。ｎは０～４の整数を表す。〕     The said light emitting layer contains the compound represented by following General formula (1) as the said host compound, The organic electroluminescent element as described in any one of Claim 1- Claim 5 characterized by the above-mentioned.
    Figure JPOXMLDOC01-appb-C000001
    [Wherein, X represents NR ′, an oxygen atom, a sulfur atom, CR′R ″, or SiR′R ″. y 1 and y 2 each represent CR ′ or a nitrogen atom. R ′ and R ″ each represent a hydrogen atom or a substituent. Ar 1 and Ar 2 each represent an aromatic ring, which may be the same or different. N represents an integer of 0 to 4.]
  7. 　前記一般式（１）におけるＸが、ＮＲ′であることを特徴とする請求項６に記載の有機エレクトロルミネッセンス素子。 The organic electroluminescent element according to claim 6, wherein X in the general formula (1) is NR '.
  8. 　前記一般式（１）におけるＸが、酸素原子であることを特徴とする請求項６に記載の有機エレクトロルミネッセンス素子。 The organic electroluminescent element according to claim 6, wherein X in the general formula (1) is an oxygen atom.
  9. 　前記一般式（１）で表される化合物が、下記一般式（２）で表される化合物であることを特徴とする請求項６から請求項８までのいずれか一項に記載の有機エレクトロルミネッセンス素子。
    Figure JPOXMLDOC01-appb-C000002
      
    〔式中、Ａｒ３～Ａｒ５は各々芳香環を表し、それぞれ同一でも異なっていても良い。ｎ１は０～４の整数を表し、ｎ２は０～５の整数を表す。〕     The organic electroluminescence according to any one of claims 6 to 8, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2). element.
    Figure JPOXMLDOC01-appb-C000002
    [Wherein Ar 3 to Ar 5 each represents an aromatic ring, and may be the same or different. n1 represents an integer of 0 to 4, and n2 represents an integer of 0 to 5. ]
  10. 　前記発光層に、更にリン光スペクトルにおける０－０遷移バンドに帰属する発光波長が、４９６～８２７ｎｍの範囲内にあるリン光発光ドーパントを含有することを特徴とする請求項１から請求項９までのいずれか一項に記載の有機エレクトロルミネッセンス素子。 10. The phosphor layer according to claim 1, further comprising a phosphorescent dopant having an emission wavelength belonging to a 0-0 transition band in a phosphorescence spectrum in a range of 496 to 827 nm. Organic electroluminescent element as described in any one of these.
  11. 　少なくとも、陽極、正孔輸送層、リン光発光性化合物を含有する発光層、電子輸送層及び陰極を有する有機エレクトロルミネッセンス素子の製造方法であって、
    　前記発光層に、発光波長が４１３～４７７ｎｍの範囲内にある量子ドットと、リン光スペクトルにおける０－０遷移バンドに帰属される発光波長が４１３～４５９ｎｍの範囲内にあるホスト化合物とを含有させ、
    　前記発光層を塗布方式で形成し、前記発光層形成用塗布液に、沸点が１００～１５０℃の範囲内にある溶媒を含有せしめることを特徴とする有機エレクトロルミネッセンス素子の製造方法。     At least an anode, a hole transport layer, a light emitting layer containing a phosphorescent compound, an electron transport layer and a method for producing an organic electroluminescent device having a cathode,
    The light emitting layer contains a quantum dot having an emission wavelength in the range of 413 to 477 nm and a host compound having an emission wavelength belonging to the 0-0 transition band in the phosphorescence spectrum in the range of 413 to 459 nm. ,
    A method for producing an organic electroluminescence device, wherein the light emitting layer is formed by a coating method, and a solvent having a boiling point in the range of 100 to 150 ° C. is contained in the coating solution for forming a light emitting layer.
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