JP2010166070A - Organic electroluminescent element and display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent element in which a highly efficient compound as an electronic transportation material is used for an electronic transporting layer or a light emitting layer, and improvement in emission luminance, emission efficiency, or long life is attained, and to provide a display using the element. <P>SOLUTION: The organic electroluminescent element includes at least one sort of compound expressed by formula (2). In the formula (2), R<SB>21</SB>, R<SB>22</SB>, R<SB>23</SB>, R<SB>24</SB>, R<SB>25</SB>, and R<SB>26</SB>denote a hydrogen atom or a monovalent substituent. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence (hereinafter sometimes abbreviated as organic EL) element and a display device. More specifically, the present invention relates to an organic electroluminescence element excellent in light emission luminance, lifetime and luminous efficiency, and The present invention relates to a display device having the organic electroluminescence element of the present invention.

  As a light-emitting electronic display device, there is an electroluminescence display (ELD). As a component of ELD, an inorganic electroluminescent element and an organic electroluminescent element are mentioned. Inorganic electroluminescent elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements. An organic electroluminescence element has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and injects electrons and holes into the light emitting layer to recombine excitons. It is an element that emits light by utilizing light emission (fluorescence / phosphorescence) generated when this exciton is deactivated, and can emit light at a voltage of several volts to several tens of volts. Therefore, it has a wide viewing angle, high visibility, and since it is a thin-film type complete solid-state device, it is attracting attention from the viewpoints of space saving and portability.

  Various organic EL elements have been reported so far. For example, Appl. Phys. Lett. , Vol. 51, 913 or a combination of a hole injection layer described in JP-A-59-194393 and an organic light-emitting layer, a hole injection layer described in JP-A-63-295695, an electron injection transport layer, , Jpn. Journal of Applied Physics, vol. 127, no. 2 A combination of the hole transfer layer, the light emitting layer, and the electron transfer layer described on pages 269 to 271 is disclosed. However, a device with higher luminance is demanded, and further improvement in energy conversion efficiency and light emission quantum efficiency is expected.

  In addition, a problem that the light emission life is short has been pointed out. The cause of this deterioration in luminance over time has not been fully elucidated, but the electroluminescent device that emits light decomposes the organic compound itself that constitutes the thin film by the light emitted by itself and the heat generated at that time. Factors derived from organic compounds, which are organic EL element materials, such as crystallization of organic compounds, have also been pointed out.

  In addition, regarding electron transport materials, there is little knowledge at present, and in combination with the use of antibonding orbitals, no useful high-performance electron transport materials that can withstand practical use have been found. For example, a research group at Kyushu University has obtained 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole (t-BuPBD), which is an oxadiazole derivative. First, 1,3-bis (4-tert-butylphenyl-1,3,4-oxadiazolyl) biphenylene (OXD-1), 1,3-bis, which is an oxadiazole dimer derivative with improved thin film stability (4-t-butylphenyl-1,3,4-oxadiazolyl) phenylene (OXD-7) (Jpn. J. Appl. Phys. Vol. 31 (1992), p. 1812) has been proposed. In addition, a research group at Yamagata University has produced a white light-emitting device by using a triazole-based electron transport material having excellent hole blocking properties (Science, 3 March 1995, Vol. 267, p. 1332). Further, JP-A-5-331459 describes that phenanthroline derivatives are useful as electron transport materials. In addition to the above, examples in which compounds containing various heteroaromatic rings are used for a light-emitting material or an electron transport material have been reported.

  Examples of the organic electroluminescent material containing a pyrimidine ring include JP-A-5-202357, JP-A-6-306357, JP-A-7-196780, and JP-A-8-199163. There are almost no examples other than the polymer of JP-A-7-196780. Examples of the light-emitting material or electron transporting material containing a triazine ring include JP-A Nos. 5-263074, 7-157473, 8-199163, 11-292860, and JP-A-11-514143.

  However, the conventional electron transporting material has a low thin film forming ability and easily crystallizes, so that there is a problem that the light emitting element is destroyed, and the light emission efficiency and the light emission lifetime are not sufficient.

  Further, in Japanese Patent No. 2,795,932, Japanese Patent Application Laid-Open Nos. 9-245511 and 5-258860, etc., the light emission from the organic EL element is absorbed, the light emission is converted, and another maximum light emission is obtained. A method for obtaining light emission of a wavelength is known. Organic fluorescent dyes are exemplified as the compounds that convert the light emission of the organic EL element. With the configuration of the above patent, a desired emission color can be obtained simply by changing the organic phosphor used in the color conversion layer. Usually, complicated patterning required for the production of a full-color organic EL is not required, and the cost can be reduced. Is possible.

  However, since the conventional electron transport material is not sufficient in terms of both light emission efficiency and light emission lifetime, the light emission intensity of the organic EL element itself is not sufficient even in the configuration using the color conversion layer, and the light emission obtained after conversion is not sufficient. The strength was still not enough.

  The present invention has found a highly efficient compound as an electron transport material, and using this for an electron transport layer or a light emitting layer, an organic electroluminescence device having improved light emission luminance and light emission efficiency and having a long lifetime, And a long-life display device using the organic electroluminescence element.

  The above object of the present invention has been achieved by the following constitutions (1) to (9).

  (1) An organic electroluminescence device comprising at least one compound represented by the following general formula (2).

(Wherein R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ and R ₂₆ represent a hydrogen atom or a monovalent substituent.)
(2) The organic electroluminescence device according to (1), wherein the compound represented by the general formula (2) is a compound represented by the following general formula (4).

_{(Wherein, R 41, R 42, R} 43, R 44 and _{R 45} represent a hydrogen atom or a monovalent substituent, Ar ₄ represents a trivalent to hexavalent radical, n4 represents 3-6. )
(3) The organic electroluminescence device as described in (1) or (2) above, wherein the compound has a molecular weight of 550 to 2,000, respectively.

  (4) The organic electroluminescence device according to any one of (1) to (3), wherein the compound is contained in an electron transport layer.

  (5) The organic electroluminescence device according to any one of (1) to (4), wherein a cathode buffer layer is provided between a cathode for injecting electrons and a layer containing the compound.

  (6) A display device comprising the organic electroluminescence element according to any one of (1) to (5).

  (7) A display device in which two or more organic electroluminescence elements according to any one of (1) to (5) having different maximum emission wavelengths are juxtaposed on the same substrate.

  (8) A display device comprising: the organic electroluminescence device according to any one of (1) to (5); and a conversion layer that absorbs light emission and emits light at a maximum wavelength different from the organic light-emitting device.

  (9) The display device according to (8), wherein two or more conversion layers having different maximum emission wavelengths are juxtaposed on the same substrate.

  Hereinafter, reference numerals 1 to 11 are configurations to be referred to.

  1. An organic electroluminescence device comprising at least one compound represented by the following general formula (1), general formula (2), or general formula (3).

(Wherein R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ each represent a hydrogen atom or a monovalent substituent, and at least one represents an aromatic hydrocarbon group. R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ and R ₂₆ represent a hydrogen atom or a monovalent substituent, R ₃₁ represents a hydrogen atom or a monovalent substituent, n3 represents 0 to 2, and Z ₃ forms a 5-membered ring. Represents the atomic group necessary for
2. An organic electroluminescence device comprising at least one compound represented by the following general formula (4).

_{(Wherein, R 41, R 42, R} 43, R 44 and _{R 45} represent a hydrogen atom or a monovalent substituent, Ar ₄ represents a trivalent to hexavalent radical, n4 represents 3-6. )
3. An organic electroluminescence device comprising at least one compound represented by the following general formula (5).

Wherein R ₅₁ , R ₅₂ and R ₅₃ are substituted with an alkyl group, a substituted or unsubstituted diazine group or an aromatic heterocyclic group having pyridine, pyrazine, pyrimidine, pyridazine, thiophene, furan and pyrrole as a partial structure. Represents an aromatic hydrocarbon group.)
4). 3. The aromatic hydrocarbon group substituted with an aromatic heterocyclic group having pyridine, pyrazine, pyrimidine, pyridazine, thiophene, furan and pyrrole as a partial structure is a substituted or unsubstituted phenyl group. The organic electroluminescent element of description.

  5. 5. The organic electroluminescence device according to any one of 1 to 4, wherein the compound has a molecular weight of 550 to 2,000, respectively.

  6). 6. The organic electroluminescence device according to any one of 1 to 5, wherein the compound is contained in an electron transport layer.

  7). 7. The organic electroluminescent device according to any one of 1 to 6, wherein a cathode buffer layer is provided between a cathode for injecting electrons and a layer containing the compound.

  8). 8. A display device comprising the organic electroluminescence element according to any one of 1 to 7 above.

  9. 8. A display device comprising two or more organic electroluminescence elements according to any one of 1 to 7 having different maximum emission wavelengths arranged side by side on the same substrate.

  10. 8. A display device comprising: the organic electroluminescence device according to any one of 1 to 7; and a conversion layer that absorbs light emission and emits light at a maximum wavelength different from the organic light-emitting device.

  11. 11. The display device as described in 10 above, wherein two or more conversion layers having different maximum emission wavelengths are juxtaposed on the same substrate.

  An organic electroluminescence device excellent in emission luminance, lifetime and emission efficiency could be obtained, and a display device with high luminance, clearness and long lifetime using the same could be provided.

It is the schematic diagram which showed an example of the display apparatus comprised from an organic electroluminescent element. It is a schematic diagram of a display part. It is a schematic diagram of a pixel. It is a schematic diagram of the display apparatus by a passive matrix system. It is sectional drawing which looked at the organic electroluminescent element which has a color conversion layer from the thickness direction.

  The present invention is described in detail below.

First, the compounds represented by general formula (1), general formula (2) and general formula (3) will be described. In the formula, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ represent a hydrogen atom or a monovalent substituent, and at least one represents an aromatic hydrocarbon group. R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ and R ₂₆ represent a hydrogen atom or a monovalent substituent. R ₃₁ represents a hydrogen atom or a monovalent substituent, n3 represents 0 to 2, Z ₃ represents an atomic group necessary to form a 5-membered ring. When R ₁₂ , R ₁₃ , R ₁₄ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ and R ₂₆ represent a substituent, the substituents may form a ring. As the monovalent substituent represented by R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ and R ₃₁ , an alkyl group (methyl group, Ethyl group, i-propyl group, hydroxyethyl group, methoxymethyl group, trifluoromethyl group, t-butyl group, cyclopentyl group, cyclohexyl group, benzyl group, etc.), alkyloxy group (methoxy group, ethoxy group, i-propoxy) Group, butoxy group etc.), aryloxy group (phenoxy group etc.), halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom etc.), aryl group (phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl) Group), alkylthio group (methylthio group, ethylthio group, i-propylthio group etc.), arylthio group (phenylthio group etc.), Amino group, a nitro group, a Hajime Tamaki (pyrrolyl, pyrrolidyl, pyrazolyl, imidazolyl, pyridyl, benzimidazolyl, benzthiazolyl, benzoxazolyl, etc.) and the like. Examples of the aromatic hydrocarbon group represented by at least one of R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. Examples of the 5-membered ring formed by Z ₃ include a pyrrole ring, a furan ring, a thiophene ring, an imidazole ring, a pyrazole ring, an oxazole ring, and a thiazole ring. Preferably, general formula (2) is represented by general formula (4), wherein R ₄₁ , R ₄₂ , R ₄₃ , R ₄₄ and R ₄₅ represent a hydrogen atom or a monovalent substituent. , Ar ₄ represents a trivalent to hexavalent group, and n4 represents 3 to 6. Examples of the monovalent substituent represented by R ₄₁ , R ₄₂ , R ₄₃ , R ₄₄ and R ₄₅ include R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , Examples thereof include the same monovalent substituents as described for R ₂₅ , R ₂₆ and R ₃₁ , and the trivalent to hexavalent group represented by Ar ₄ is not particularly limited, but is a bond of 3 to 6 Examples thereof include an aliphatic hydrocarbon group having a hand, a monocyclic group, and a condensed polycyclic group. Further, a structural unit in which the aliphatic hydrocarbon group or the like is connected by a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom or the like is also included. Specific examples include the following structural units, but are not limited thereto.

In addition, they may each independently have a plurality of arbitrary substituents, and the plurality of substituents may be condensed with each other to further form a ring. The plurality of quinazoline rings substituted for Ar ₄ may be the same or different.

Next, general formula (5) will be described. In the formula, R ₅₁ , R ₅₂ and R ₅₃ are substituted or unsubstituted alkyl groups, substituted or unsubstituted diazine groups or aromatic heterocycles having pyridine, pyrazine, pyrimidine, pyridazine, thiophene, furan and pyrrole rings as partial structures. An aromatic hydrocarbon group substituted with a cyclic group. The alkyl group represented by R ₅₁ , R ₅₂ and R ₅₃ is the same as the alkyl group exemplified as the monovalent substituent represented by R ₁₁ , R ₁₂ and R ₁₃ in the general formula (1). Can be mentioned. Examples of the diazine group include a pyridazine group, a pyrimidine group, and a pyrazine group, which may further have a substituent, and when having a plurality of substituents, they may be bonded to each other to form a ring. Good.

R ₅₁ , R ₅₂ and R ₅₃ are preferably a phenyl group substituted with an aromatic heterocyclic group having a pyridine, pyrazine, pyrimidine, pyridazine, thiophene, furan and pyrrole ring as a partial structure.

  The compounds represented by the general formulas (1), (2), (3), (4) and (5) used in the present invention preferably have a molecular weight of 550 to 2,000. When the molecular weight is 550 to 2,000, Tg (glass transition temperature) is increased, and the thermal stability is improved.

  The band gap of the compounds represented by the general formulas (1), (2), (3), (4) and (5) of the present invention is preferably 2.96 eV to 3.80 eV, It is preferably 3.20 eV to 3.80 eV. By taking such a high value, the hole blocking property is improved while maintaining the electron transport property, and the luminous efficiency is further improved. The band gap of the compound of the present invention has a high value of 3.65 eV, 3.26 eV, for example, in compounds II-2, V-8, etc., and has a relatively low band gap, for example, among the compounds of the present invention. For example, the luminous efficiency is higher than that of the compounds of I-9 and I-10 (although the band gaps are 2.90 and 2.85, respectively).

  The band gap as used herein refers to the difference between the ionization potential and electron affinity of a compound, and the ionization potential and electron affinity are determined with reference to the vacuum level. The ionization potential is defined by the energy required to emit electrons at the HOMO (highest occupied molecular orbital) level of the compound to the vacuum level, and the electron affinity is the LUMO (lowest empty molecule) of the electron at the vacuum level. Defined by the energy that falls to the orbital level and stabilizes. The difference between the ionization potential and the electron affinity can be converted from the absorption edge of the absorption spectrum of the compound. In the present invention, the absorption spectrum of the deposited film is measured when the compound is deposited on glass to a thickness of 100 nm. The wavelength Ynm at the absorption edge was calculated by converting to XeV. At this time, the following conversion formula was used.

X = 1240 / Y
Although the specific example of the compound example represented by General formula (1)-(5) below is shown, it is not limited to these.

  The compound of the present invention is a compound having strong fluorescence in the solid state, is excellent in electroluminescence, and can be used effectively as a light emitting material. Moreover, since it is very excellent in the electron injection property and electron transport property from a metal electrode, when it uses as an electron transport material in the element using another light emitting material, it shows the outstanding luminous efficiency.

  The organic EL device of the present invention has a hole transport layer, an anode buffer layer, a cathode buffer layer, etc. in addition to a light emitting layer and an electron transport layer using these compounds as required, and is sandwiched between a cathode and an anode. Take the structured.

In particular,
(I) Anode / light emitting layer / cathode (ii) Anode / hole transport layer / light emitting layer / cathode (iii) Anode / light emitting layer / electron transport layer / cathode (iv) Anode / hole transport layer / light emitting layer / electron Transport layer / cathode (v) Anode / anode buffer layer / hole transport layer / light emitting layer / electron transport layer / cathode buffer layer / cathode structure.

  The compound of the present invention may be contained in any layer, but is preferably contained in the light emitting layer or the electron transport layer, and particularly preferably contained in the electron transport layer.

  The light-emitting layer 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 an interface between adjacent layers.

  The material used for the light emitting layer (hereinafter referred to as the light emitting material) is preferably an organic compound or complex that emits fluorescence or phosphorescence, and is appropriately selected from known materials used for the light emitting layer of the organic EL device. Can be used. Such a light-emitting material is mainly an organic compound, and has a desired color tone, for example, Macromol. Synth. 125, pages 17-25, and the like.

  The light emitting material may have a hole transport function and an electron transport function in addition to the light emitting performance, and most of the hole transport material and the electron transport material can be used as the light emitting material.

  The light-emitting material may be a polymer material such as p-polyphenylene vinylene or polyfluorene, and a polymer material in which the light-emitting material is introduced into a polymer chain or the light-emitting material is a polymer main chain is used. May be.

  In addition, a dopant (guest material) may be used in combination with the light emitting layer, and an arbitrary one can be selected from known materials used as a dopant for an EL element. Specific examples of the dopant include quinacridone, DCM, coumarin derivatives, rhodamine, rubrene, decacyclene, pyrazoline derivatives, squarylium derivatives, europium complexes, iridium complexes, platinum complexes and the like.

  This light emitting layer can be formed by forming the above compound by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method. Although the film thickness as a light emitting layer does not have a restriction | limiting in particular, Usually, it selects in the range of 5 nm-5 micrometers. This light emitting layer may have a single layer structure composed of one or two or more of these light emitting materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.

  Further, as described in JP-A-57-51781, this light emitting layer is prepared by dissolving the above light emitting material in a solvent together with a binder such as a resin, and then using a spin coating method or the like. It can be formed as a thin film. There is no restriction | limiting in particular about the film thickness of the light emitting layer formed in this way, Although it can select suitably according to a condition, Usually, it is the range of 5 nm-5 micrometers.

  The organic EL element of the present invention absorbs light emitted from the organic EL element, converts the light emission, and obtains light having a maximum emission wavelength different from that, and contains a compound that converts light emitted from the organic EL element. In the case of having a conversion layer, the light emission from the light emitting layer is preferably in the blue-violet region in terms of conversion efficiency.

  In the organic EL device of the present invention, the color of the blue-violet region, which is the light emitted from the light emitting layer, is measured with a measuring instrument such as a spectral radiance meter CS-1000 (manufactured by Minolta). When applied to coordinates (Figure 4.16 on page 108 of the “New Color and Color Science Handbook” (Edited by the Japan Society for Color Science, University of Tokyo Press, 1985)), Purple Blue (purple blue) or Bluish Purple (blue purple) When it is in the area.

  As general characteristics of the compound exhibiting light emission in the blue-violet region, those having a fluorescence maximum wavelength in a solution of 350 nm to 420 nm are preferable, and those having a fluorescence quantum yield of 0.1 or more are preferable.

  Specific examples of such a light emitting material include JP-A-2001-143869, JP-A-2001-160488, JP-A-2001-81453, JP-A-2001-93670, Japanese Patent Application Nos. 2000-265045, 2000-285050. No. 2000-292124, No. 2000-290466, No. 2000-240880, No. 2000-345267, and the like.

  Some specific examples are shown below, but are not limited thereto.

  Next, the hole transport layer and the electron transport layer will be described.

  The hole transport layer has a function of transmitting holes injected from the anode to the light emitting layer. By interposing this hole transport layer between the anode and the light emitting layer, a large number of holes can be formed at a lower electric field. Are injected into the light emitting layer, and the electrons injected into the light emitting layer from the cathode, the cathode buffer layer, or the electron transport layer are interfaced in the light emitting layer due to an electron barrier existing at the interface between the light emitting layer and the hole transport layer. In other words, the light emitting efficiency is improved. The material of the hole transport layer (hereinafter referred to as a hole injection material or a hole transport material) is not particularly limited as long as it has the above-mentioned preferable properties. Any material commonly used as an injection transport material and known materials used for a hole transport layer of an EL element can be selected and used.

  The hole transport material has one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. Examples of the hole transport material include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives. Fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers. As the hole transport material, those described above can be used, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of the aromatic tertiary amine compound and styrylamine compound include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N ′. -Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; Bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p- Tolylaminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N′-diphenyl-N, N -Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadri N; N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenyl Amino- (2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbenzene; N-phenylcarbazole and further described in US Pat. No. 5,061,569 Having two condensed aromatic rings in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-3 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 8688 are linked in a starburst type ( MTDATA).

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole transport material. The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, it is about 5 nm-5 micrometers. The hole transport layer may have a single layer structure composed of one or more of the above materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

  Furthermore, the electron transport layer used as necessary only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer, and the material thereof is selected from any conventionally known compounds. Can be used.

  Examples of materials used for this electron transport layer (hereinafter referred to as electron transport materials) include heterocyclic tetracarboxylic acid anhydrides such as nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, naphthalene perylene, carbodiimides, Examples include fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, triazole derivatives, and phenanthroline derivatives. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material.

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg, Cu , Ca, Sn, Ga, or Pb can also be used as an electron transport material. 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 transport material. Further, a distyrylpyrazine derivative used as a material for the light-emitting layer can also be used as an electron transport material. Similarly to the hole transport layer, inorganic semiconductors such as n-type-Si and n-type-SiC can also be used as an electron transport material. Can be used as

  This electron transport layer can be formed by forming the above compound by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method. Although the film thickness as an electron carrying layer does not have a restriction | limiting in particular, Usually, it selects in 5 nm-5 micrometers. The electron transport layer may have a single layer structure composed of one or two or more of these electron transport materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.

  Further, a buffer layer (electrode interface 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 buffer layer is a layer that is provided between the electrode and the organic layer in order to lower the driving voltage and improve the light emission efficiency. “The organic EL element and the forefront of its industrialization (issued on November 30, 1998 by NTS Corporation) 2) Chapter 2 “Electrode Materials” (pages 123 to 166) in detail, and includes an anode buffer layer and a cathode buffer layer.

  The details of the anode buffer layer are described in JP-A-9-45479, 9-260062, and 8-288069. Specific examples thereof include a phthalocyanine buffer layer represented by copper phthalocyanine, and vanadium oxide. And an oxide buffer layer, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  The details of the cathode buffer layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, a metal buffer layer represented by strontium, aluminum and the like, Examples thereof include 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.

  In particular, in the organic EL device of the present invention, when the cathode buffer layer was present, a significant reduction in driving voltage and an improvement in luminous efficiency were obtained.

  The buffer layer is preferably a very thin film, and depending on the material, the film thickness is preferably in the range of 0.1 to 100 nm.

  Further, in addition to the basic constituent layer, a layer having other functions may be laminated as required. For example, JP-A-11-204258, JP-A-11-204359, and “Organic EL device and its industrialization front line ( It may have a functional layer such as a hole blocking layer described on page 237 of "November 30, 1998, NTS Corporation").

  Next, the electrode of the organic EL element will be described. The electrode of the organic EL element consists of a cathode and an anode.

As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode substances include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO.

  The anode may be formed by forming a thin film by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when the pattern accuracy is not so high (100 μm). As described above, a pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. When light emission is extracted from the anode, the transmittance is desirably greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 nm to 1 μm, preferably 10 to 200 nm.

On the other hand, as the cathode, a material having a low 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 is 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, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this from the viewpoint of durability against electron injecting and oxidation, for example, a magnesium / silver mixture, magnesium An aluminum / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, and the like are preferable.

  Furthermore, as the cathode used in the organic EL device of the present invention, an aluminum alloy is preferable, and the aluminum content is particularly preferably 90% by mass or more and less than 100% by mass, and most preferably 95% by mass or more and less than 100% by mass. . Thereby, the light emission lifetime and the highest reached luminance of the organic EL element can be greatly improved.

  The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. Further, the sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 1 μm, preferably 50 to 200 nm. In order to transmit light, if either the anode or the cathode of the organic EL element is transparent or translucent, the light emission efficiency is improved, which is convenient.

  The substrate preferably used for the organic EL device of the present invention is not particularly limited in the kind of glass, plastic and the like, and is not particularly limited as long as it is transparent. Examples of the substrate preferably used in the electroluminescent device of the present invention include glass, quartz, and a light transmissive plastic film.

  Examples of the light transmissive plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, and polycarbonate (PC). And a film made of cellulose triacetate (TAC), cellulose acetate propionate (CAP), or the like.

  Next, a suitable example for producing the organic EL element will be described. As an example, a method for producing an EL device comprising the anode / anode buffer layer / hole transport layer / light emitting layer / electron transport layer / cathode buffer layer / cathode will be described. First, a desired electrode material is formed on a suitable substrate. For example, a thin film made of a material for an anode is formed 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 10 to 200 nm, to produce an anode. Next, a thin film made of materials of an anode buffer layer, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode buffer layer is formed thereon.

  As a method for thinning the organic thin film layer, there are a spin coating method, a casting method, a vapor deposition method and the like as described above. From the viewpoint that a homogeneous film is easily obtained and pinholes are not easily generated. Vapor deposition or spin coating is particularly preferred. Further, a different film forming method may be applied for each layer. When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, the target crystal structure of the molecular deposition film, the association structure, etc. It is desirable to select appropriately within the range of −6 to 10−2 Pa, the deposition rate of 0.01 to 50 nm / second, the substrate temperature of −50 to 300 ° C., and the film thickness of 5 nm to 5 μm.

  After forming these layers, 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, and a cathode is provided. Thus, a desired EL element can be obtained. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but it may be taken out in the middle and subjected to a different film forming method. Therefore, it is necessary to consider that the work is performed in a dry inert gas atmosphere.

  Moreover, it is also possible to reverse the production order and produce the cathode, the cathode buffer layer, the electron transport layer, the light emitting layer, the hole transport layer, the anode buffer layer, and the anode in this order. When a DC voltage is applied to the EL element thus obtained, light emission can be observed by applying a voltage of about 5 to 40 V with the anode being + and the cathode being-. Further, even when a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The alternating current waveform to be applied may be arbitrary.

  The organic EL element of the present invention may be used as a kind of lamp such as an illumination or exposure light source, or a projection device that projects an image, or a display device that directly recognizes a still image or a moving image. (Display) may be used. When used as a display device for reproducing moving images, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. Moreover, it is possible to create a full-color display device by using two or more organic EL elements of the present invention having different emission colors.

  Next, the color conversion layer will be described.

  The color conversion layer referred to in this specification refers to a layer having a function of converting light having a certain wavelength into light having a different wavelength in a broad sense. Specifically, it refers to a layer containing substances that absorb light emitted from the light emitting layer of the organic EL element and emit light of different wavelengths. Thus, the organic EL element can display not only the color of light emitted from the light emitting layer but also other colors converted by the color conversion layer.

  Examples of the substance that absorbs light emitted from the light emitting layer of the organic EL element and emits light of different wavelengths include phosphors, and the phosphors may be organic phosphors or inorganic phosphors, which are used depending on the wavelength to be converted. Can do.

  Organic phosphors include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, stilbene dyes Examples thereof include dyes and polythiophene dyes.

  The inorganic phosphor is preferably a fine particle having a particle size of 3 μm or less, and the production method is preferably an ultrafine particle phosphor close to synthesized monodisperse via a liquid phase method.

  Examples of the inorganic phosphor include an inorganic phosphor composed of a crystal matrix and an activator, or a rare earth complex phosphor.

The composition of the inorganic phosphor is not particularly limited, but metal oxides such as Y ₂ O ₂ S, Zn ₂ SiO ₄ , Ca ₅ (PO ₄ ) ₃ Cl, etc., which are crystal bases, and ZnS, SrS, CaS. And sulfides such as Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and other rare earth metal ions, Ag, Al, Mn, In, Cu A combination of metal ions such as Sb as activator or coactivator is preferable.

The crystal matrix will be described in more detail. As the crystal matrix, a metal oxide is preferable. For example, (X) ₃ Al ₁₆ O ₂₇ , (X) ₄ Al ₁₄ O ₂₅ , (X) ₃ Al ₂ Si ₂ O ₁₀ , ( X) ₄ Si ₂ O ₈ , (X) ₂ Si ₂ O ₆ , (X) ₂ P ₂ O ₇ , (X) ₂ P ₂ O ₅ , (X) ₅ (PO ₄ ) ₃ Cl, (X) ₂ Si ₃ O ₈ -2 (X) Cl ₂ [wherein X represents an alkaline earth metal. The alkaline earth metal represented by X may be a single component or two or more mixed components, and the mixing ratio may be arbitrary. As typical crystal bases, aluminum oxide, silicon oxide, phosphoric acid, halophosphoric acid and the like substituted with an alkaline earth metal such as

  Other preferable crystal matrixes include oxides and sulfides of zinc, oxides of rare earth metals such as yttrium, gadolinium and lanthanum, and oxides in which part of the oxygen is replaced with sulfur atoms (sulfides), and Examples include rare earth metal sulfides and oxides or sulfides thereof containing any metal element.

  Preferred examples of the crystal matrix are listed below.

Mg ₄ GeO _5.5 F, Mg ₄ GeO ₆ , ZnS, Y ₂ O ₂ S, Y ₃ Al ₅ O ₁₂ , Y ₂ SiO ₁₀ , Zn ₂ SiO ₄ , Y ₂ O ₃ , BaMgAl ₁₀ O ₁₇ , BaAl ₁₂ O ₁₉ , (Ba, Sr, Mg) O.aAl ₂ O ₃ , (Y, Gd) BO ₃ , (Zn, Cd) S, SrGa ₂ S ₄ , SrS, GaS, SnO ₂ , Ca ₁₀ (PO ₄ ) ₆ (F, Cl) ₂ , (Ba, Sr) (Mg, Mn) Al ₁₀ O ₁₇ , (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ , (La, Ce) PO ₄ , CeMgAl ₁₁ O ₁₉ , GdMgB ₅ O ₁₀ , Sr ₂ P ₂ O ₇ , Sr ₄ Al ₁₄ O ₂₅ , Y ₂ SO ₄ , Gd ₂ O ₂ S, Gd ₂ O ₃ , YVO ₄ , Y (P, V) O ₄ Etc.

  The above crystal matrix and activator or coactivator may be partially replaced with elements of the same family, and there is no particular limitation on the element composition, so long as it absorbs light in the blue-violet region and emits visible light. Good.

  In the present invention, preferred as the activator and coactivator of the inorganic phosphor are the ions of lanthanoid elements represented by La, Eu, Tb, Ce, Yb, Pr, etc., Ag, Mn, Cu, In, Al The ion amount of the metal is preferably 0.001 to 100 mol%, more preferably 0.01 to 50 mol% with respect to the base material.

  The activator and coactivator are doped into the crystal by replacing some of the ions constituting the crystal matrix with ions such as the above lanthanoids.

Strictly speaking, the actual composition of the phosphor crystal has the following composition formula, but since the amount of the activator often does not affect the intrinsic fluorescence properties, the following is especially true: Unless otherwise specified, the following numerical values of x and y are not described. For example, Sr _4-x Al ₁₄ O ₂₅ : Eu ²⁺ _x is expressed as Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ in the present invention.

The composition formulas of typical inorganic phosphors (inorganic phosphors composed of a crystal matrix and an activator) are described below, but the present invention is not limited to these. _{(Ba z Mg 1-z)} 3-x-y Al 16 O 27: Eu 2+ x, Mn 2+ y, Sr 4-x Al 14 O 25: Eu 2+ x, (Sr 1-z Ba z) 1-x Al ₂ Si ₂ O ₈ : Eu ²⁺ _x , Ba _2−x SiO ₄ : Eu ²⁺ _x , Sr _2−x SiO ₄ : Eu ²⁺ _x , Mg _2−x SiO ₄ : Eu ²⁺ _x , (BaSr) _1-x SiO ₄ : Eu ²⁺ _x , Y _2−x−y SiO ₅ : Ce ³⁺ _x , Tb ³⁺ _y , Sr _2−x P ₂ O ₅ : Eu ²⁺ _x , Sr _2−x P ₂ O ₇ : Eu ²⁺ _x , _{(Ba y Ca z Mg 1-} y-z) 5-x (PO 4) 3 Cl: Eu 2+ x, Sr 2-x Si 3 O 8 -2SrCl 2: Eu 2+ x [x, y and z are each 1 The following arbitrary numbers are represented. ]
The inorganic phosphors preferably used in the present invention are shown below, but the present invention is not limited to these compounds.

[Blue light emitting inorganic phosphor]
(BL-1) Sr ₂ P ₂ O ₇ : Sn ⁴⁺
(BL-2) Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺
(BL-3) BaMgAl ₁₀ O ₁₇ : Eu ²⁺
(BL-4) SrGa ₂ S ₄ : Ce ³⁺
(BL-5) CaGa ₂ S ₄ : Ce ³⁺
(BL-6) (Ba, Sr) (Mg, Mn) Al ₁₀ O ₁₇ : Eu ²⁺
(BL-7) (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺
(BL-8) BaAl ₂ SiO ₈ : Eu ²⁺
(BL-9) Sr ₂ P ₂ O ₇ : Eu ²⁺
_{(BL-10) Sr 5 (} PO 4) 3 Cl: Eu 2+
(BL-11) (Sr, Ca, Ba) ₅ (PO ₄ ) ₃ Cl: Eu ²⁺
_{(BL-12) BaMg 2 Al} 16 O 27: Eu 2+
(BL-13) (Ba, Ca) ₅ (PO ₄ ) ₃ Cl: Eu ²⁺
(BL-14) Ba ₃ MgSi ₂ O ₈ : Eu ²⁺
(BL-15) Sr ₃ MgSi ₂ O ₈ : Eu ²⁺
[Green light emitting inorganic phosphor]
(GL-1) (BaMg) Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺
(GL-2) Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺
(GL-3) (SrBa) Al ₂ Si ₂ O ₈ : Eu ²⁺
(GL-4) (BaMg) ₂ SiO ₄ : Eu ^{2+
_{(GL-5) Y 2 SiO}} 5: Ce 3+, Tb 3+
_{(GL-6) Sr 2 P} 2 O 7 -Sr 2 B 2 O 5: Eu 2+
(GL-7) (BaCaMg) ₅ (PO ₄ ) ₃ Cl: Eu ²⁺
_{(GL-8) Sr 2 Si} 3 O 8 -2SrCl 2: Eu 2+
_{(GL-9) Zr 2 SiO} 4, MgAl 11 O 19: Ce 3+, Tb 3+
(GL-10) Ba ₂ SiO ₄ : Eu ²⁺
(GL-11) Sr ₂ SiO ₄ : Eu ²⁺
_{(GL-12) (BaSr)} SiO 4: Eu 2+
[Red light-emitting inorganic phosphor]
(RL-1) Y ₂ O ₂ S: Eu ³⁺
(RL-2) YAlO ₃ : Eu ³⁺
(RL-3) Ca ₂ Y ₂ (SiO ₄ ) ₆ : Eu ³⁺
(RL-4) LiY ₉ (SiO ₄ ) ₆ O ₂ : Eu ³⁺
(RL-5) YVO ₄ : Eu ³⁺
(RL-6) CaS: Eu ³⁺
(RL-7) Gd ₂ O ₃ : Eu ³⁺
(RL-8) Gd ₂ O ₂ S: Eu ³⁺
(RL-9) Y (P, V) O ₄ : Eu ³⁺
(RL-10) Mg ₄ GeO _5.5 F: Mn ⁴⁺
(RL-11) Mg ₄ GeO ₆ : Mn ⁴⁺
(RL-12) K ₅ Eu _2.5 (WO ₄ ) _6.25
(RL-13) Na ₅ Eu _2.5 (WO ₄ ) _6.25
(RL-14) K ₅ Eu _2.5 (MoO ₄ ) _6.25
(RL-15) Na ₅ Eu _2.5 (MoO ₄ ) _6.25
The inorganic phosphor may be subjected to a surface modification treatment as required, and as a method thereof, a chemical treatment such as a silane coupling agent or a physical treatment by adding submicron order fine particles or the like. And those obtained by using them in combination.

  Examples of rare earth complex phosphors include those having Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, etc. as rare earth metals. The ligand may be either aromatic or non-aromatic, and is preferably a compound represented by the following general formula (B).

Formula _{(B) Xa- (L x)} - (L y) n- (L z) -Ya
(Wherein L _x , L _y , and L _z each independently represent an atom having two or more bonds, n represents 0 or 1, Xa is adjacent to L _x , and Represents a substituent having an atom capable of coordinating, and Ya represents a substituent which is adjacent to L _z and has an atom capable of coordinating to the rare earth metal, and an arbitrary portion of Xa and Lx A ring may be condensed to form any part of Ya and L _z may be condensed with each other to form a ring, or L _x and L _z may be condensed with each other to form a ring. well, further aromatic hydrocarbon ring or an aromatic heterocyclic ring in the molecule is at least one present, _{however, Xa- (L x) -.} (L y) n - (L z) -Ya is β- diketone derivative Ya β-ketoester derivative, β-ketoamide derivative or oxygen atom of the ketone is a sulfur atom Is -N (R _{201) -} are replaced in, crown ethers and aza crown ether or thia crown ether or crown any number sulfur atoms or -N oxygen atom of an ether (R _{201) -} represents the crown ether is replaced with In some cases, there may be no aromatic hydrocarbon ring or aromatic heterocyclic ring, and in -N (R ₂₀₁ ) —, R ₂₀₁ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group. Represents.)
In the general formula (B), the coordinateable atoms represented by Xa and Ya are specifically an oxygen atom, a nitrogen atom, a sulfur atom, a selenium atom, and a tellurium atom, particularly an oxygen atom, a nitrogen atom, A sulfur atom is preferred.

In the general formula (B), the atom having two or more bonds represented by L _x , L _y , and L _z is not particularly limited, but typically, a carbon atom, an oxygen atom, a nitrogen atom, A silicon atom, a titanium atom, etc. are mentioned, A preferable one is a carbon atom.

  Specific examples of the rare earth complex phosphor represented by the general formula (B) are shown below, but the present invention is not limited thereto.

  The location where the color conversion layer is provided is not particularly limited as long as it can absorb light emitted from the organic EL portion, but is between the transparent electrode and the transparent substrate or on the opposite side of the transparent substrate from the transparent electrode ( It is preferably provided on the front side).

The color conversion layer may be in any form such as film formation by vapor deposition or sputtering of the phosphor, or a coating film in which an appropriate resin is dispersed as a binder. The film thickness is suitably about 100 nm to 5 mm. Here, when an appropriate resin is used as a binder to form a coating film dispersed therein, the phosphor dispersion concentration does not cause fluorescence concentration quenching and sufficiently absorbs light emitted from the organic EL portion. As long as it is within the range, depending on the type of phosphor, about 10 ⁻⁷ to 10 ⁻³ mol is suitable for 1 g of the resin used. In the case of an inorganic phosphor, since concentration quenching hardly causes a problem, about 0.1 to 10 g can be used with respect to 1 g of resin.

  As a color conversion layer used in the present invention, a color conversion layer containing an inorganic phosphor that emits light having a maximum emission wavelength in the range of 400 to 500 nm when excited by the emission wavelength of the organic compound in the emission layer, and emission A color conversion layer containing an inorganic phosphor that emits light with a maximum emission wavelength in the range of 501 to 600 nm when excited by the emission wavelength of the organic compound in the layer, and excited by the emission wavelength of the organic compound in the emission layer It is preferable to have at least a color conversion layer containing an inorganic phosphor that emits light having a maximum emission wavelength within a range of 601 to 700 nm. Thereby, the organic EL element can be made full color.

  An example of a display device composed of the organic electroluminescence element of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic view showing an example of a display device composed of organic electroluminescence elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic electroluminescence element.

  The display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.

  The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside. The pixels for each scanning line are converted into image data signals by the scanning signal. In response to this, light is sequentially emitted and image scanning is performed to display image information on the display unit A.

  FIG. 2 is a schematic diagram of the display unit.

  The display unit A includes a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate. The main members of the display unit A will be described below.

  In the figure, the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

  The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions (details are shown in FIG. Not shown).

  When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data. Full color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region that emit light on the same substrate.

  Next, the light emission process of the pixel will be described.

  FIG. 3 is a schematic diagram of a pixel.

  The pixel includes an organic electroluminescence element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. Full-color display can be performed by using the red, green, and blue light emitting organic electroluminescence elements of Examples 1 to 3 as the organic electroluminescence element 10 for a plurality of pixels and juxtaposing them on the same substrate.

  In FIG. 3, an image data signal is applied from the control unit B to the drain of the switching transistor 11 through the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.

  By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive of the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic electroluminescence element 10, and the organic electroluminescence element is connected from the power supply line 7 according to the potential of the image data signal applied to the gate. 10 is supplied with current.

  When the scanning signal is moved to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, even if the driving of the switching transistor 11 is turned off, the capacitor 13 maintains the potential of the charged image data signal, so that the driving of the driving transistor 12 is kept on and the next scanning signal is applied. The organic electroluminescence device 10 continues to emit light up to the point. When a scanning signal is next applied by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic electroluminescence element 10 emits light.

  That is, the organic electroluminescence element 10 emits light by providing the switching transistor 11 and the driving transistor 12 which are active elements with respect to the organic electroluminescence element 10 of each of the plurality of pixels. 10 lights are emitted. Such a light emitting method is called an active matrix method.

  Here, light emission of the organic electroluminescence element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or a predetermined light emission amount on by a binary image data signal. It may be off.

  The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.

  In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which the organic electroluminescence element emits light according to the data signal only when the scanning signal is scanned.

  FIG. 4 is a schematic view of a passive matrix display device. In FIG. 4, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.

  When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal.

  In the passive matrix system, the pixel 3 has no active element, and the manufacturing cost can be reduced.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this.

Example 1 (electron transport material)
After patterning on a substrate having a 150 nm ITO film formed on glass as an anode (NH Techno Glass, NA-45), the transparent support substrate provided with this ITO transparent electrode was ultrasonically washed with isopropyl alcohol and dried. It dried with nitrogen gas and performed UV ozone washing | cleaning for 5 minutes. This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus, while 200 mg of m-MTDATA is put into a molybdenum resistance heating boat, and 200 mg of DPVBi is put into another resistance heating boat made of molybdenum. 200 mg of BC was placed in a molybdenum resistance heating boat and attached to a vacuum deposition apparatus.

Next, after depressurizing the vacuum tank to 4 × 10 ⁻⁴ Pa, energizing the heating boat containing m-MTDATA, heating to 220 ° C., and transparent support at a deposition rate of 0.1 to 0.3 nm / sec. The substrate is deposited with a film thickness of 25 nm and a hole transport layer is provided. Further, the heating boat containing DPVBi is energized and heated to 220 ° C., and the film thickness is 20 nm at a deposition rate of 0.1 to 0.3 nm / sec. The light emitting layer was provided. The substrate temperature during vapor deposition was room temperature.

  Subsequently, the heating boat containing BC was energized and heated to 220 ° C., and an electron transport layer of 30 nm was provided at a deposition rate of 0.1 to 0.3 nm / sec.

Next, a vacuum chamber is opened, and a stainless steel rectangular perforated mask is placed on the electron transport layer. On the other hand, 3 g of magnesium is placed in a molybdenum resistance heating boat, and 0.02 of silver is placed in a tungsten vapor deposition basket. 5 g was added and the vacuum chamber was again depressurized to 2 × 10 ⁻⁴ Pa, and then the magnesium-containing boat was energized to deposit magnesium at a deposition rate of 1.5 to 2.0 nm / sec. Was heated, and silver was vapor-deposited at a vapor deposition rate of 0.1 nm / sec to obtain a cathode made of the mixture of magnesium and silver, thereby producing a comparative organic EL element OLED1-1 shown in Table 1.

  Organic electroluminescent elements OLED1-2 to 21 were produced in the same manner as organic electroluminescent element OLED1-1 except that BC (electron transport layer) of organic EL element OLED1-1 was changed to the compounds shown in Table 1. .

These devices are continuously lit by applying a 15 V DC voltage in a dry nitrogen gas atmosphere at a temperature of 23 degrees, light emission luminance at the start of lighting (cd / m ² ), time to reduce the luminance by half, and light emission efficiency (ln / W) Was measured. The light emission luminance and the light emission efficiency are expressed as relative values when the organic electroluminescence element OLED1-1 is 100, and the time when the luminance is halved is also a relative value when the time when the luminance of the organic electroluminescence element OLED1-1 is halved is 100. expressed. The results are shown in Table 1. The emission color was blue.

The light emission luminance (cd / m ² ) and the light emission efficiency (ln / W) were measured using Minolta CS-1000.

  From Table 1, it can be seen that the organic EL device using the compound of the present invention has improved light emission luminance at the start of lighting, time to reduce the luminance by half, and light emission efficiency. In particular, it can be seen that the time for halving the luminance is improved. Further, II-13, II-16, V-3, V-4, and V-11 used as the electron transport materials of the organic electroluminescence elements OLED1-10, 12, 16, 17, and 21 have a band gap of 3. It is in the range of .20 eV to 3.60 eV, and it can be seen that the light emission luminance and the light emission efficiency are greatly improved.

Example 2
Except that the cathode of the organic electroluminescent element OLED1-10 produced in Example 1 was replaced with Al and lithium fluoride was deposited to a thickness of 0.5 nm between the electron transport layer and the cathode to provide a cathode buffer layer. Thus, an organic electroluminescence element (OLED2-1) was produced.

As in Example 1, the light emission luminance at the start of lighting (cd / m ² ), the time to reduce the luminance by half, and the light emission efficiency (ln / W) were measured, and compared with the organic electroluminescence element OLED1-1. The luminance was 203, the luminance was reduced by half 521, and the luminous efficiency was 199. Similarly, the organic electroluminescence elements OLED1-4 to 9 and 1-10 to 21 were more effective when a cathode buffer layer was introduced.

Example 3
Similarly, the organic electroluminescence element used in Example 1 was replaced with a light emitting layer in which Alq ₃ or Alq ₃ and DCM 2 were deposited from DPVBi at a mass ratio of 100: 1, respectively, from DPVBi. Was made.

As in Example 1, the light emission luminance (cd / m ² ) at the start of lighting, the time to reduce the luminance by half, and the light emission efficiency (ln / W) were measured. As a result, in the organic electroluminescence device using the compound of the present invention, It was confirmed that the light emission luminance at the start of lighting, the time to reduce the luminance by half, and the light emission efficiency were improved.

When Alq ₃ was used as the light emitting layer, green light emission was obtained, and red light emission was obtained from the light emitting layer in which Alq ₃ and DCM2 were 100: 1.

Example 4
The red, green, and blue light emitting organic electroluminescence elements produced in Examples 1 and 3 were juxtaposed on the same substrate to produce the active matrix type full color display device shown in FIGS. By driving the full-color display device, a clear full-color moving image display with high luminance was obtained.

Example 5
After patterning on a substrate having a 150 nm ITO film formed on glass as an anode (NH Techno Glass, NA-45), the transparent support substrate provided with this ITO transparent electrode was ultrasonically washed with isopropyl alcohol and dried. It dried with nitrogen gas and performed UV ozone washing | cleaning for 5 minutes. This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus, while 200 mg of m-MTDATA is put into a molybdenum resistance heating boat, and N, N′-diphenyl-N is put into another molybdenum resistance heating boat. , N′-bis (3-methylphenyl) [1,1′-biphenyl] -4,4′-diamine (TPD) is added to 200 mg, and another molybdenum resistance heating boat is charged with 200 mg of BC. 200 mg of the following comparative compound 3 was put in a resistance heating boat made of molybdenum, and attached to a vacuum deposition apparatus.

Next, after depressurizing the vacuum tank to 4 × 10 ⁻⁴ Pa, energizing the heating boat containing m-MTDATA, heating to 220 ° C., and transparent support at a deposition rate of 0.1 to 0.3 nm / sec. Vapor deposited on the substrate with a film thickness of 25 nm, further energized to the heating boat containing TPD, heated to 220 ° C., vapor deposited at a film deposition rate of 0.1 to 0.3 nm / sec with a film thickness of 20 nm, and two layers A hole transport layer comprising: The substrate temperature during vapor deposition was room temperature.

  Then, the heating boat containing the comparative compound 3 was energized and heated to 220 ° C., and a 30 nm light emitting layer was provided at a deposition rate of 0.1 to 0.3 nm / sec. Further, the heating boat containing BC was energized and heated to 220 ° C., and an electron transport layer having a thickness of 20 nm was provided at a deposition rate of 0.1 to 0.3 nm / sec.

Next, a vacuum chamber is opened, and a stainless steel rectangular perforated mask is placed on the electron injection layer. On the other hand, 3 g of magnesium is put into a molybdenum resistance heating boat, and 0.02 of silver is put into a tungsten vapor deposition basket. 5 g was added and the vacuum chamber was again depressurized to 2 × 10 ⁻⁴ Pa, and then the magnesium-containing boat was energized to deposit magnesium at a deposition rate of 1.5 to 2.0 nm / sec. Was heated, and silver was vapor-deposited at a vapor deposition rate of 0.1 nm / sec to obtain a cathode made of the mixture of magnesium and silver, thereby producing a comparative organic EL element OLED5-1 shown in Table 2.

  Organic EL elements OLED5-2 to 7 were produced in the same manner as the organic EL element OLED5-1 except that the comparative compound 3 of the organic EL element OLED5-1 was changed to the compounds shown in Table 2.

These devices are continuously lit by applying a 15 V DC voltage in a dry nitrogen gas atmosphere at a temperature of 23 degrees, light emission luminance at the start of lighting (cd / m ² ), time to reduce the luminance by half, and light emission efficiency (ln / W) Was measured. The light emission luminance and the light emission efficiency are expressed as relative values when the organic EL element OLED5-1 is 100, and the time when the luminance is halved is expressed as a relative value when the time when the luminance of the organic electroluminescence element OLED5-1 is halved is 100. did. The results are shown in Table 2.

  From Table 2, it can be seen that the organic EL device using the compound of the present invention has improved the light emission luminance at the start of lighting, the light emission efficiency, and the time to reduce the luminance by half.

Example 6
Organic electroluminescent element OLED6-1 was produced by the same method as Example 5 except using the light emitting layer with a film thickness of 30 nm which vapor-deposited compound I-10 of this invention and DCM2 by the mass ratio of 100: 1.

  When these devices were applied with a DC voltage of 15 V in a dry nitrogen gas atmosphere at a temperature of 23 degrees, red light emission was obtained.

  Green or blue light emission was obtained by changing DCM2 of the organic electroluminescence element OLED6-1 to Qd-2 or BCzVBi, respectively.

  Similarly, when the compound I-10 of the organic electroluminescence element OLED6-1 was replaced with V-12 and DCM2, Qd-2 and BCzVBi were used as dopants, red, green or blue light emission was obtained.

Example 7
In the organic electroluminescence element OLED1-10 produced in Example 1, the hole transport material is m-MTDATXA, the organic compound of the light emitting layer is BP-13, the cathode is Al, and lithium fluoride is provided between the electron transport layer and the cathode. An organic electroluminescence element (OLED7-1) was produced in the same manner except that the film thickness was 0.5 nm and the cathode buffer layer was provided.

<Preparation of color conversion filter using inorganic phosphor>
15 g of ethanol and 0.22 g of γ-glycidoxypropyltriethoxysilane were added to 0.16 g of aerosil having an average particle diameter of 5 nm, and the mixture was stirred at room temperature for 1 hour. This mixture and the inorganic phosphor RL-12 were transferred to a 20 g mortar and mixed well, and then heated in a 70 ° C. oven for 2 hours and further in a 120 ° C. oven for 2 hours to obtain a surface-modified inorganic phosphor RL-12. Obtained.

  Similarly, the surface modification of the inorganic phosphors GL-10 and BL-3 was also performed.

  30 g of polyvinyl butyral resin ESREC BX-1 (manufactured by Sekisui Chemical Co., Ltd.) dissolved in a mixed solution (300 g) of toluene / ethanol = 1/1 was added to 10 g of the above surface-modified (RL-12), and stirred. Then, it was coated on glass with a wet film thickness of 200 μm. The obtained coated glass was heat-dried in an oven at 100 ° C. for 4 hours to produce a red conversion filter (F-1) in which a color conversion layer was formed on the glass.

  Also, a green color conversion filter (F-2) coated with (GL-10) and a blue color conversion filter (F-3) coated with (BL-3) were produced in the same manner.

  Subsequently, a blue color conversion filter (F-3) was attached in a stripe shape as a color conversion part on the lower side of the transparent substrate of the organic electroluminescence element (OLED 7-1). The organic electroluminescence element of this example has the following configuration.

Color conversion part / transparent substrate / anode / organic compound thin film / cathode When a voltage of 15 V was applied to the device, 320 cd / m ^{2 of} clear blue light emission was obtained. The maximum emission wavelength of the emission spectrum was 448 nm and (0.15, 0.06) on the CIE chromaticity coordinates.

Furthermore, the organic electroluminescent element which replaced the blue color conversion filter (F-3) of the said color conversion part with the green color conversion filter (F-2) or the red color conversion filter (F-1) was produced. As a result, from the organic electroluminescence device provided with the green conversion filter (F-2), green light of 250 cd / m ² , a maximum emission wavelength of 532 nm, and CIE chromaticity coordinates (0.24, 0.63) From the organic electroluminescence element provided with the red conversion filter (F-1), red light of 170 cd / m ² , maximum emission wavelength 615 nm, and CIE chromaticity coordinates (0.63, 0.33) is obtained. It was.

  The emission luminances of blue light, green light, and red light are all superior to those of the organic electroluminescence elements described in Examples of Japanese Patent No. 2795932.

  Moreover, the organic electroluminescent element of the following layer structures which changed the position of the following color conversion parts to the upper side of a transparent substrate was produced.

Transparent substrate / color conversion part / anode / organic compound thin film / cathode In this case as well, an emission spectrum having the same maximum emission wavelength and CIE chromaticity coordinates as those of blue, green and red was obtained.

Example 8 (full-color display device)
In the display unit A having the plurality of pixels 3 in FIG. 2, a display device in which all of the plurality of organic electroluminescence elements included in the plurality of pixels 3 are the organic electroluminescence elements (OLEDs 7-1) described in the seventh embodiment. Was made. At this time, when a voltage was applied to the display device, blue-violet light emission was obtained from all the pixels 3.

  Next, the organic electroluminescent element (FIG. 5A) described in Example 5 and the organic electroluminescent element (FIG. 5B) in which the position of the transparent substrate and the color conversion layer are different from this were prepared. FIG. 5 is a cross-sectional view of an organic electroluminescence element having a color conversion layer as seen from the thickness direction. In FIG. 5A, the organic electroluminescence element 10 has an organic EL portion Y laminated on the upper side of a glass transparent substrate 10d and a color conversion portion X laminated on the lower side.

  In the figure, reference numeral 10a denotes a cathode made of Al, 10b denotes an organic compound thin film in which a cathode buffer layer (lithium fluoride), an electron transport layer (BC), a light emitting layer (BP-13) and the like are laminated, and 10c denotes an anode. (ITO transparent electrode), 10d is a transparent substrate, 10e is a red conversion filter (F-1), a green conversion filter (F-2), and a blue conversion filter (F-3) prepared in Example 7 arranged in stripes. The color conversion layer.

  When current was supplied to the organic compound thin film 10b via the cathode 10a and the transparent electrode 10c, light was emitted according to the amount of current. The light emission at this time was taken out in the downward direction in the figure. The emitted light is absorbed by the color conversion layer 10e through the transparent substrate 10d. When the color conversion layer has a red conversion ability (the red conversion filter (F-1) portion), the green conversion ability in the red region is obtained. When it has (green conversion filter (F-2) part), it emits light in the green region, and when it has blue conversion ability (blue conversion filter (F-3) part), it emits light in the blue region. I was able to take it out in the direction of the arrow.

  As shown in FIG. 5B, even when the color conversion portion X and the organic EL portion Y are stacked in this order on the upper side of the transparent substrate 10d, red, green, and blue are the same as in the case of FIG. Was obtained. By driving the display device, a clear full-color moving image display with high brightness was obtained.

DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power supply line 10 Organic electroluminescent element 10a Cathode 10b Organic compound thin film 10c Transparent electrode 10d Transparent substrate 10e Color conversion layer 11 Switching transistor 12 Drive transistor 13 Capacitor A Display part (display)
B Control unit X Color conversion unit Y Organic EL unit

Claims (9)

An organic electroluminescence device comprising at least one compound represented by the following general formula (2).

(Wherein R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ and R ₂₆ represent a hydrogen atom or a monovalent substituent.) The organic electroluminescent device according to claim 1, wherein the compound represented by the general formula (2) is a compound represented by the following general formula (4).

_{(Wherein, R 41, R 42, R} 43, R 44 and _{R 45} represent a hydrogen atom or a monovalent substituent, Ar ₄ represents a trivalent to hexavalent radical, n4 represents 3-6. )   3. The organic electroluminescence device according to claim 1, wherein the compound has a molecular weight of 550 to 2,000, respectively.   The organic electroluminescent element according to claim 1, wherein the compound is contained in an electron transport layer.   5. The organic electroluminescence device according to claim 1, further comprising a cathode buffer layer between a cathode for injecting electrons and the layer containing the compound.   A display device comprising the organic electroluminescence element according to claim 1.   6. A display device comprising two or more organic electroluminescence elements according to claim 1 having different maximum emission wavelengths arranged on the same substrate.   6. A display device comprising: the organic electroluminescence element according to claim 1; and a conversion layer that absorbs light emission and emits light at a maximum wavelength different from the organic light-emitting element.   9. The display device according to claim 8, wherein two or more conversion layers having different maximum emission wavelengths are juxtaposed on the same substrate.

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