JP2007131723A - Electroluminescent element material and electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroluminescent element material capable of providing an electroluminescent element excellent in durability and to provide an electroluminescent element using the electroluminescent element material. <P>SOLUTION: The electroluminescent element material comprises a pyrene compound represented by formula (1) (wherein R<SP>1</SP>to R<SP>15</SP>are each selected from hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group or the like and a condensed ring formed between adjacent substituents, with the proviso that at least one among R<SP>1</SP>-R<SP>10</SP>is singly bonded to A; Y<SP>1</SP>-Y<SP>5</SP>are selected from a nitrogen atom and a carbon atom, with the proviso that at least one among Y<SP>1</SP>to Y<SP>5</SP>is the nitrogen atom, and R<SP>11</SP>to R<SP>15</SP>which are substituents on the nitrogen atom do not exist in the case of the nitrogen atom). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light-emitting element material useful as a fluorescent dye or a charge transport material and a light-emitting element using the same, and includes a display element, a flat panel display, a backlight, illumination, an interior, a sign, a signboard, an electrophotographic machine, and light The present invention relates to a light-emitting element that can be used in a field such as a signal generator.

  In recent years, research on organic thin-film light-emitting devices that emit light when electrons injected from a cathode and holes injected from an anode are recombined in an organic phosphor sandwiched between both electrodes has been actively conducted. This light-emitting element is characterized by thin light emission with high luminance under a low driving voltage and multicolor light emission by selecting a light-emitting material.

This study was conducted by Eastman Kodak's C.I. W. Since Tang et al. Have shown that organic thin film elements emit light with high brightness, many research institutions have studied. A typical structure of the organic thin-film light-emitting device presented by the Kodak research group is a hole-transporting diamine compound, a light-emitting layer of tris (8-quinolinolato) aluminum (III), and a cathode. As a result, Mg: Ag (alloy) was sequentially provided, and green light emission of 1000 cd / m ² was possible with a driving voltage of about 10 V (see Non-Patent Document 1).

  In addition, organic thin-film light-emitting elements can be obtained in various emission colors by using various fluorescent materials for the light-emitting layer, and therefore, researches for practical application to displays and the like are actively conducted. Among the three primary color luminescent materials, research on the green luminescent material is the most advanced, and at present, intensive research is being conducted to improve the characteristics of the red and blue luminescent materials.

One of the biggest challenges in organic thin film light emitting devices is to increase the durability of the devices. In particular, with respect to blue light-emitting elements, there are few blue light-emitting materials that provide elements with excellent durability and high reliability. For example, a technique using a styrylamine derivative (see Patent Document 1) or a perylene derivative (see Patent Document 2) as a blue dopant material is disclosed. In addition, a technique using a pyrene compound for a blue light emitting element is disclosed. Although blue light emitting devices using various pyrene compounds (see Patent Documents 3 to 6) have been reported, all of them have insufficient durability.
JP-A-5-17765 (Claim 1) JP 2003-86380 A (Claim 2) JP 2001-118682 A (Claim 1) JP 2003-272864 A (Claim 1) JP 2004-75567 A (Claims 1 to 4) International Publication No. 2004/096945 (Patents) Applied Physics Letters (USA), 1987, 51, 12, 913-915

  As described above, the conventional organic thin-film light-emitting element has not been provided with a blue light-emitting element having high luminous efficiency and excellent durability. Accordingly, an object of the present invention is to solve the problems of the prior art, and to provide a light emitting element material that enables a blue light emitting element with high luminous efficiency and excellent durability, and a light emitting element using the same. .

  The present invention is a light emitting device material comprising a pyrene compound represented by the following general formula (1).

R ^{1 to} R ¹⁵ may be the same as or different from each other, and are hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether Group, aryl group, heteroaryl group, halogen, cyano group, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, phosphine oxide group, and a condensed ring formed between adjacent substituents To be elected. However, at least one of R ^{1 to} R ¹⁰ and A are single-bonded. Y ^{1 to} Y ⁵ are selected from nitrogen and carbon atoms. However, at least one of Y ^{1 to} Y ⁵ is a nitrogen atom, and in the case of a nitrogen atom, R ^{11 to} R ¹⁵ that are substituents on the nitrogen atom do not exist.

  Further, the present invention is a light emitting element that has at least a light emitting layer between an anode and a cathode and emits light by electric energy, and the light emitting element contains a light emitting element material represented by the general formula (1). A light-emitting element is characterized.

  By using the light emitting device material of the present invention, a light emitting device having high luminous efficiency and excellent durability can be obtained. In addition, a light-emitting element material having excellent thin film stability can be provided.

  The pyrene compound represented by the general formula (1) used in the light emitting device material of the present invention will be described.

R ^{1 to} R ¹⁵ may be the same as or different from each other, and are hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether Group, aryl group, heteroaryl group, halogen, cyano group, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, phosphine oxide group, and a condensed ring formed between adjacent substituents To be elected. However, at least one of R ^{1 to} R ¹⁰ and A are single-bonded. Y ^{1 to} Y ⁵ are selected from nitrogen and carbon atoms. However, at least one of Y ^{1 to} Y ⁵ is a nitrogen atom, and in the case of a nitrogen atom, R ^{11 to} R ¹⁵ that are substituents on the nitrogen atom do not exist.

  Among these substituents, the alkyl group is, for example, a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group. This may or may not have a substituent. There is no restriction | limiting in particular in the additional substituent in the case of being substituted, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned, This point is common also in the following description. The number of carbon atoms of the alkyl group is not particularly limited, but is usually in the range of 1 to 20 and more preferably 1 to 8 from the viewpoint of availability and cost.

  The cycloalkyl group represents a saturated alicyclic hydrocarbon group such as cyclopropyl, cyclohexyl, norbornyl, adamantyl, etc., which may or may not have a substituent. Although carbon number of an alkyl group part is not specifically limited, Usually, it is the range of 3-20.

  The heterocyclic group refers to an aliphatic ring having atoms other than carbon, such as a pyran ring, a piperidine ring, and a cyclic amide, in the ring, which may or may not have a substituent. . Although carbon number of a heterocyclic group is not specifically limited, Usually, it is the range of 2-20.

  An alkenyl group shows the unsaturated aliphatic hydrocarbon group containing double bonds, such as a vinyl group, an allyl group, and a butadienyl group, and this may or may not have a substituent. Although carbon number of an alkenyl group is not specifically limited, Usually, it is the range of 2-20.

  The cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond such as a cyclopentenyl group, a cyclopentadienyl group, or a cyclohexenyl group, which may have a substituent. You don't have to.

  An alkynyl group shows the unsaturated aliphatic hydrocarbon group containing triple bonds, such as an ethynyl group, for example, and may or may not have a substituent. Although carbon number of an alkynyl group is not specifically limited, Usually, it is the range of 2-20.

  The alkoxy group refers to, for example, a functional group having an aliphatic hydrocarbon group bonded through an ether bond such as a methoxy group, an ethoxy group, or a propoxy group, and the aliphatic hydrocarbon group may have a substituent. It may not have. Although carbon number of an alkoxy group is not specifically limited, Usually, it is the range of 1-20.

  The alkylthio group is a group in which an oxygen atom of an ether bond of an alkoxy group is substituted with a sulfur atom. The hydrocarbon group of the alkylthio group may or may not have a substituent. Although carbon number of an alkylthio group is not specifically limited, Usually, it is the range of 1-20.

  An aryl ether group refers to a functional group to which an aromatic hydrocarbon group is bonded via an ether bond, such as a phenoxy group, and the aromatic hydrocarbon group may or may not have a substituent. Good. Although carbon number of an aryl ether group is not specifically limited, Usually, it is the range of 6-40.

  An aryl thioether group is one in which the oxygen atom of the ether bond of the aryl ether group is substituted with a sulfur atom. The aromatic hydrocarbon group in the aryl ether group may or may not have a substituent. Although carbon number of an aryl ether group is not specifically limited, Usually, it is the range of 6-40.

  An aryl group refers to an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group, a terphenyl group, or a pyrenyl group. The aryl group may or may not have a substituent. Although carbon number of an aryl group is not specifically limited, Usually, it is the range of 6-40.

  A heteroaryl group refers to an aromatic group having a non-carbon atom in the ring, such as a furanyl group, a thiophenyl group, an oxazolyl group, a pyridyl group, a quinolinyl group, or a carbazolyl group, which has a substituent. Even if it does not have. Although carbon number of heteroaryl group is not specifically limited, Usually, it is the range of 2-30.

  The halogen atom represents fluorine, chlorine, bromine or iodine.

  The carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, and phosphine oxide group may or may not have a substituent. Examples of the substituent include an alkyl group, a cycloalkyl group, and an aryl group. , Heteroaryl groups and the like, and these substituents may be further substituted.

When the condensed ring formed between adjacent groups is described in the general formula (1), any two adjacent substituents selected from R ^{1 to} R ¹⁴ (for example, R ¹ and R ² ) are mutually bonded. Bonded to form a conjugated or non-serving fused ring. These condensed rings may contain nitrogen, oxygen, or sulfur atoms in the ring structure, or may be condensed with another ring, but the atoms constituting these condensed rings are only carbon atoms and hydrogen atoms. It is preferable because excellent heat resistance can be obtained.

The pyrene compound represented by the general formula (1) of the present invention has high emission efficiency and excellent heat resistance by having a pyrene skeleton and a nitrogen-containing heteroaryl skeleton that is an electron-accepting heterocycle in the molecule. is doing. Here, any one of R ^{1 to} R ¹⁰ and A are single-bonded. From the availability of raw materials and the ease of synthesis, at least one of R ¹ , R ³ , R ⁶ , and R ⁸ A is preferably a single bond. Y ¹ to Y ⁴ in the general formula (1) are selected from nitrogen and carbon atoms, and at least one of Y ^{1 to} Y ⁴ is a nitrogen atom.

From the viewpoints of availability of raw materials, ease of synthesis, and high efficiency light emission, a pyrene compound in which at least one of Y ¹ to Y ⁵ is a nitrogen atom is preferable.

Moreover, when the pyrene compound represented by the general formula (1) of the present invention is at least one of R ^{1 to} R ¹⁰ is an aryl group or a heteroaryl group, the interaction between the pyrene compounds is suppressed, and high It is preferable because efficient light emission is possible. Furthermore, it is more preferable that at least one of R ¹ , R ⁶ , R ³ , and R ⁸ is an aryl group or a heteroaryl group because the effect of suppressing interaction between pyrene compounds is increased.

  Although it does not specifically limit as a pyrene compound represented by the above General formula (1), Specifically, the following examples are given.

  A known method can be used for the synthesis of the pyrene compound represented by the general formula (1). Methods for introducing an aryl group or heteroaryl group into the pyrene skeleton include, for example, a method using a coupling reaction under a palladium or nickel catalyst with a halogenated pyrene derivative and an aryl or heteroaryl metal reagent, or aryl halide or halogenation. Examples include, but are not limited to, a method using a coupling reaction of teloaryl and a pyrene derivative boronic acid under a palladium or nickel catalyst.

  Next, embodiments of the light-emitting element in the present invention will be described with examples. The light emitting device of the present invention comprises at least an anode and a cathode, and an organic layer made of a light emitting device material interposed between the anode and the cathode.

  The anode used in the present invention is not particularly limited as long as it can efficiently inject holes into the organic layer. However, it is preferable to use a material having a relatively large work function, for example, tin oxide, indium oxide, zinc oxide. Conductive metal oxides such as indium and indium tin oxide (ITO), metals such as gold, silver and chromium, inorganic conductive materials such as copper iodide and copper sulfide, conductive polymers such as polythiophene, polypyrrole and polyaniline, etc. Is mentioned. These electrode materials may be used alone, or a plurality of materials may be laminated or mixed.

  The resistance of the electrode is not limited as long as a current sufficient for light emission of the light-emitting element can be supplied, and is preferably low from the viewpoint of power consumption of the light-emitting element. For example, an ITO substrate of 300Ω / □ or less will function as a device electrode, but since it is now possible to supply a substrate of about 10Ω / □, use a low-resistance product of 100Ω / □ or less. Is particularly desirable. The thickness of ITO can be arbitrarily selected according to the resistance value, but is usually used in a range of 100 to 300 nm.

In order to maintain the mechanical strength of the light emitting element, the light emitting element is preferably formed over a substrate. As the substrate, a glass substrate such as soda glass or non-alkali glass is preferably used. As the thickness of the glass substrate, it is sufficient that the thickness is sufficient to maintain the mechanical strength. The glass material is preferably alkali-free glass because it is better to have less ions eluted from the glass, but soda lime glass with a barrier coat such as SiO ₂ is also available on the market. it can. Furthermore, if the anode functions stably, the substrate does not have to be glass. For example, the anode may be formed on a plastic substrate. The ITO film forming method is not particularly limited, such as an electron beam method, a sputtering method, and a chemical reaction method.

  The material used for the cathode used in the present invention is not particularly limited as long as it can efficiently inject electrons into the organic layer, but is generally platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, Examples thereof include chromium, lithium, sodium, potassium, cesium, calcium, magnesium, and alloys thereof. Lithium, sodium, potassium, cesium, calcium, magnesium, or alloys containing these low work function metals are effective for increasing the electron injection efficiency and improving device characteristics. However, these low work function metals are generally unstable in the atmosphere. For example, the organic layer is doped with a small amount of lithium or magnesium (1 nm or less in the vacuum vapor deposition thickness meter display) to be stable. A method using a high electrode can be cited as a preferred example. Also, an inorganic salt such as lithium fluoride can be used. Furthermore, for electrode protection, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, and inorganic substances such as silica, titania and silicon nitride, polyvinyl alcohol, vinyl chloride Lamination of hydrocarbon polymer compounds and the like is a preferred example. The method for producing these electrodes is not particularly limited as long as conduction can be achieved, such as resistance heating, electron beam, sputtering, ion plating, and coating.

  The light-emitting element of the present invention is formed of a light-emitting element material in which the organic layer contains a pyrene compound represented by the general formula (1). The light-emitting element material corresponds to either a compound that emits light by itself or a compound that assists the light emission, and refers to a compound that participates in light emission. Specifically, a hole-transport material, a light-emitting material, and an electron This includes transportation materials.

  The organic layer constituting the light emitting device of the present invention is composed of at least a light emitting layer made of a light emitting device material. As an example of the organic layer configuration, in addition to the configuration consisting of only the light emitting layer, 1) hole transport layer / light emitting layer / electron transport layer and 2) light emitting layer / electron transport layer, 3) hole transport layer / light emission A laminated structure such as a layer can be mentioned. Moreover, each said layer may consist of a single layer, respectively, and may consist of multiple layers. When the hole transport layer and the electron transport layer are composed of a plurality of layers, the layers in contact with the electrodes may be referred to as a hole injection layer and an electron injection layer, respectively. In the material, the electron injection material is included in the electron transport material.

  The hole transport layer is formed by laminating and mixing one or more hole transport materials or a mixture of the hole transport material and the polymer binder. Examples of the hole transport material include 4,4′-bis (N- (3-methylphenyl) -N-phenylamino) biphenyl and 4,4′-bis (N- (1-naphthyl) -N-phenyl. Amino) biphenyl, triphenylamine derivatives such as 4,4 ′, 4 ″ -tris (3-methylphenyl (phenyl) amino) triphenylamine, bis (N-allylcarbazole) or bis (N-alkylcarbazole) Biscarbazole derivatives, pyrazoline derivatives, stilbene compounds, hydrazone compounds, benzofuran derivatives and thiophene derivatives, heterocyclic compounds such as oxadiazole derivatives, phthalocyanine derivatives, porphyrin derivatives, polycarbonates having the above monomers in the side chain in polymer systems And styrene derivatives, polythiophene, polyaniline Polyfluorene, polyvinylcarbazole, polysilane, and the like are preferable, but there is no particular limitation as long as it is a compound that can form a thin film necessary for manufacturing a light-emitting element, can inject holes from the anode, and can further transport holes. .

  In the present invention, the light emitting layer may be either a single layer or a plurality of layers, each formed of a light emitting material (host material, dopant material), which may be a mixture of a host material and a dopant material, Either the material alone or the material may be used. That is, in the light emitting element of the present invention, only the host material or the dopant material may emit light in each light emitting layer, or both the host material and the dopant material may emit light. Each of the host material and the dopant material may be one kind or a plurality of combinations. The dopant material may be included in the entire host material or may be partially included. The dopant material may be laminated or dispersed. If the amount of the dopant material is too large, a concentration quenching phenomenon occurs, so that it is preferably used at 20% by weight or less, more preferably 10% by weight or less with respect to the host material. As a doping method, it can be formed by a co-evaporation method with a host material, but it may be pre-mixed with the host material and then simultaneously deposited.

  The pyrene compound represented by the general formula (1) of the present invention is suitably used as a light emitting material. Further, since the pyrene compound of the present invention exhibits strong light emission in the blue region, it is preferably used as a blue light-emitting material, but is not limited thereto, and is a material for green to red light-emitting elements and white light-emitting elements. Can also be used. The pyrene compound of the present invention may be used as a host material, but is preferably used as a dopant material because it has a high fluorescence quantum yield and a narrow spectral half width.

  The ionization potential of the pyrene compound represented by the general formula (1) of the present invention is not particularly limited, but is preferably 5 eV or more and 7 eV or less, more preferably 5.4 eV or more and 6.4 eV or less. . Although it has been reported that the absolute value of the ionization potential varies depending on the measurement method, the ionization potential of the present invention is measured using an atmospheric-type ultraviolet photoelectron analyzer (AC-1, manufactured by Riken Kikai Co., Ltd.) This is a value obtained by measuring a thin film deposited on an ITO glass substrate to a thickness of 30 nm to 100 nm.

  The dopant material used in the present invention need not be limited to only one kind of the pyrene compound. Even if a plurality of pyrene compounds are mixed and used, one or more kinds of known dopant materials are mixed and used with the pyrene compound. Also good. Specifically, conventionally known compounds having an aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, triphenylene, perylene, fluorene, indene and derivatives thereof, furan, pyrrole, thiophene, silole, 9-silafluorene, Compounds having a heteroaryl ring such as 9,9′-spirobisilafluorene, benzothiophene, benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine, thioxanthene, and derivatives thereof; Distyrylbenzene derivative, aminostyryl derivative, aromatic acetylene derivative, tetraphenylbutadiene derivative, stilbene derivative, aldazine derivative, coumarin derivative, imidazole , Azole derivatives such as thiazole, thiadiazole, carbazole, oxazole, oxadiazole, triazole and their metal complexes and fragrances represented by 4,4′-bis (N- (3-methylphenyl) -N-phenylamino) biphenyl Group amine derivatives and the like, but are not limited thereto.

  The host material contained in the light-emitting material is not particularly limited, but is a compound having a condensed aryl ring such as anthracene or pyrene, which has been known as a light-emitting material, or a derivative thereof, or 4,4′-bis. Bisstyryl derivatives such as aromatic amine derivatives such as (N- (1-naphthyl) -N-phenylamino) biphenyl, metal chelated oxinoid compounds such as tris (8-quinolinolato) aluminum (III), and distyrylbenzene derivatives , Tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, oxadiazole derivatives, carbazole derivatives, pyrrolopyrrole derivatives, polymers, polyphenylene vinylene derivatives Body, polyparaphenylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, polythiophene derivatives are suitably used. Among them, it is preferable to use an anthracene compound or pyrene compound having an electron-donating substituent as a host material because the durability improving effect becomes remarkable when combined with the pyrene compound of the present invention. Specifically, an anthracene compound having a carbazole group represented by 9- (4- (carbazol-N-yl) phenyl) -10- (4-methylphenyl) anthracene is particularly preferable.

  In the present invention, the electron transport layer is a layer that administers electrons injected from the cathode and further transports electrons. It is desirable that the electron transport efficiency is high and the injected electrons are transported efficiently. For this purpose, it is required that the material has a high electron affinity, a high electron mobility, excellent stability, and a substance that does not easily generate trapping impurities during manufacturing and use. However, considering the transport balance between holes and electrons, if the role of effectively preventing the holes from the anode from flowing to the cathode side without recombination is mainly played, the electron transport capability is much higher. Even if it is not high, the effect of improving the luminous efficiency is equivalent to that of a material having a high electron transport capability. Therefore, the electron transport layer in the present invention includes a hole blocking layer that can efficiently block the movement of holes as the same meaning.

  The electron transporting material used for the electron transporting layer is not particularly limited, but is typically a compound having a condensed aryl ring such as naphthalene or anthracene or a derivative thereof, or 4,4′-bis (diphenylethenyl) biphenyl. Styryl aromatic ring derivatives, perylene derivatives, perinone derivatives, coumarin derivatives, naphthalimide derivatives, quinone derivatives such as anthraquinone and diphenoquinone, phosphorus oxide derivatives, carbazole derivatives and indole derivatives, tris (8-quinolinolato) aluminum (III), etc. Hydroxy azole complexes such as quinolinol complexes and hydroxyphenyl oxazole complexes, azomethine complexes, tropolone metal complexes and flavonol metal complexes, compounds consisting of heteroaryl rings having electron-accepting nitrogen, etc. It is below.

  The electron-accepting nitrogen in the present invention represents a nitrogen atom that forms a multiple bond with an adjacent atom. Since the nitrogen atom has a high electronegativity, the multiple bond has an electron accepting property. Therefore, a heteroaryl ring having an electron-accepting nitrogen has a high electron affinity. Examples of the heteroaryl ring having an electron-accepting nitrogen include, for example, a pyridine ring, pyrazine ring, pyrimidine ring, quinoline ring, quinoxaline ring, naphthyridine ring, pyrimidopyrimidine ring, benzoquinoline ring, phenanthroline ring, imidazole ring, oxazole ring, Examples thereof include an oxadiazole ring, a triazole ring, a thiazole ring, a thiadiazole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring and a phenanthrimidazole ring.

  In addition, the compound composed of a heteroaryl ring having electron-accepting nitrogen of the present invention is preferably composed of an element selected from the group consisting of carbon, hydrogen, nitrogen, oxygen, silicon and phosphorus. A compound composed of a heteroaryl ring having an electron-accepting nitrogen composed of these elements has a high electron transporting ability and can significantly reduce a driving voltage.

  Examples of the compound composed of a heteroaryl ring having an electron-accepting nitrogen and composed of an element selected from the group consisting of carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus include, for example, benzimidazole derivatives and benzoxazole derivatives , Benzthiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, quinoline derivatives, benzoquinoline derivatives, oligopyridine derivatives such as bipyridine and terpyridine, quinoxaline derivatives and naphthyridine derivatives As mentioned. Among them, imidazole derivatives such as tris (N-phenylbenzimidazol-2-yl) benzene, oxadiazole derivatives such as 1,3-bis [(4-tert-butylphenyl) 1,3,4-oxadiazolyl] phenylene, Triazole derivatives such as N-naphthyl-2,5-diphenyl-1,3,4-triazole, phenanthroline derivatives such as bathocuproine and 1,3-bis (2-phenyl-1,10-phenanthroline-9-yl) benzene, Benzoquinoline derivatives such as 2,2′-bis (benzo [h] quinolin-2-yl) -9,9′-spirobifluorene, 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl) ) -1,1-dimethyl-3,4-diphenylsilole and other bipyridine derivatives, 1,3-bis (4 ′-(2,2 ′) 6′2 ″ -terpyridinyl)) terpyridine derivatives such as benzene and naphthyridine derivatives such as bis (1-naphthyl) -4- (1,8-naphthyridin-2-yl) phenylphosphine oxide are preferable from the viewpoint of electron transport ability. Used. Furthermore, 1,3-bis (1,10-phenanthroline-9-yl) benzene, 2,7-bis (1,10-phenanthroline-9-yl) naphthalene, 1,3-bis (2-phenyl-1, Phenanthroline dimers such as 10-phenanthroline-9-yl) benzene, 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl))-1,1-dimethyl-3,4-diphenylsilole, etc. This bipyridine dimer has a significantly high durability improving effect when combined with the pyrene compound represented by the general formula (1) of the present invention, and is particularly preferable.

  These electron transport materials may be used alone, but two or more of the above electron transport materials may be mixed and used, or one or more of the other electron transport materials may be mixed and used in the above electron transport material. . It is also possible to use a mixture with a metal such as an alkali metal or an alkaline earth metal. The ionization potential of the electron transport layer is not particularly limited, but is preferably 5.8 to 8 eV, and more preferably 6 to 7.5 eV.

  The method of forming each layer constituting the light emitting element is not particularly limited, such as resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination method, coating method, etc., but resistance heating vapor deposition or electron beam vapor deposition is usually used for the element. It is preferable from the viewpoint of characteristics.

  The thickness of the layer depends on the resistance value of the luminescent material and cannot be limited, but is selected from 1 to 1000 nm. The film thicknesses of the light emitting layer, the electron transport layer, and the hole transport layer are each preferably 1 nm to 200 nm, and more preferably 5 nm to 100 nm.

  The light-emitting element of the present invention is a light-emitting element that can convert electrical energy into light. Here, the electric energy mainly indicates a direct current, but a pulse current or an alternating current can also be used. The current value and voltage value are not particularly limited, but in consideration of the power consumption and life of the element, the maximum luminance should be obtained with as low energy as possible.

  The light emitting device of the present invention is suitably used as a display for displaying in a matrix and / or segment system, for example.

  The matrix system in the present invention refers to a display in which pixels for display are two-dimensionally arranged such as a lattice shape or a mosaic shape, and a character or an image is displayed by a set of pixels. The shape and size of the pixel are determined by the application. For example, a square pixel with a side of 300 μm or less is usually used for displaying images and characters on a personal computer, monitor, TV, and a pixel with a side of mm order for a large display such as a display panel. become. In monochrome display, pixels of the same color may be arranged. However, in color display, red, green, and blue pixels are displayed side by side. In this case, there are typically a delta type and a stripe type. The matrix driving method may be either a line sequential driving method or an active matrix. The line-sequential driving has an advantage that the structure is simple. However, the active matrix may be superior in consideration of operation characteristics, so that it is necessary to use them depending on the application.

  In the segment system (type) in the present invention, a pattern is formed so as to display predetermined information, and a predetermined region is caused to emit light. For example, the time and temperature display in a digital clock or a thermometer, the operation state display of an audio device or an electromagnetic cooker, the panel display of an automobile, and the like can be mentioned. The matrix display and the segment display may coexist in the same panel.

  The light emitting device of the present invention is also preferably used as a backlight for various devices. The backlight is used mainly for the purpose of improving the visibility of a display device that does not emit light, and is used for a liquid crystal display device, a clock, an audio device, an automobile panel, a display panel, a sign, and the like. In particular, as a backlight for a liquid crystal display device, especially a personal computer for which thinning is a problem, considering that it is difficult to thin the conventional backlight because it is made of a fluorescent lamp or a light guide plate, the present invention A backlight using the light emitting element can be thin and lightweight.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited by these Examples. In addition, the number of the compound in each following Example points out the number of the compound described in the above chemical formula.

Example 1 (Synthesis of Compound [25])
Under a nitrogen stream, a mixed solution of 4.8 mL of bromine and 200 mL of carbon tetrachloride was added dropwise to a mixed solution of 28.1 g of 1-bromopyrene and 800 mL of carbon tetrachloride, and stirred at room temperature for 10 hours. The precipitated solid was filtered, and the solid was washed with methanol. The obtained solid was recrystallized twice using toluene to obtain 9.16 g of 1,6-dibromopyrene.

  A mixed solution of 6 g of 1,6-dibromopyre, 5.69 g of 4-methylphenylboronic acid, 17.7 g of tripotassium phosphate, 2.69 g of tetrabutylammonium bromide, 115 mg of palladium acetate and 90 ml of degassed dimethylformamide The mixture was heated and stirred at 130 ° C. for 16 hours under a nitrogen stream. After cooling to room temperature, 450 ml of water was poured, and the precipitated solid was filtered. The obtained solid was dissolved in dichloromethane, washed with 200 ml of water, dried over magnesium sulfate, and concentrated by evaporation. The obtained solid was recrystallized from toluene to obtain 4.58 g of 1,6-di (4-methylphenyl) pyrene as light brown scaly crystals.

  A mixed solution of 4.58 g of 1,6-di (4-methylphenyl) pyrene, 2.16 g of N-bromosuccinimide and 120 ml of dimethylformamide was stirred at 60 ° C. for 12 hours under a nitrogen stream. The precipitated solid was filtered, washed with water and dried to obtain 4.93 g of 1-bromo-3,8-di (4-methylphenyl) pyrene.

  4.93 g of 1-bromo-3,8-di (4-methylphenyl) pyrene, 2.78 g of 3-quinolineboronic acid, 4.54 g of tripotassium phosphate, 690 mg of tetrabutylammonium bromide, 96 mg of palladium acetate were removed. The mixed solution with 100 ml of vaporized dimethylformamide was heated and stirred at 130 ° C. for 16 hours under a nitrogen stream. After cooling to room temperature, 500 ml of water was poured, and the precipitated solid was filtered. The obtained solid was dissolved in dichloromethane, washed with 200 ml of water, dried over magnesium sulfate, and concentrated by evaporation. The obtained solid was purified by silica gel column chromatography to obtain 2.18 g of compound [25].

Example 2
A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam evaporated product) on which an ITO transparent conductive film was deposited to 150 nm was cut into 30 × 40 mm and etched. The obtained substrate was ultrasonically washed with acetone and “Semicocrine 56” (manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes, respectively, and then washed with ultrapure water. Subsequently, it was ultrasonically cleaned with isopropyl alcohol for 15 minutes and then immersed in hot methanol for 15 minutes and dried. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁵ Pa or less. By the resistance heating method, first, copper phthalocyanine was deposited as a hole injecting material at 10 nm, and 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl was deposited as a hole transporting material at 50 nm. Next, as a light-emitting material, H-1 shown below as a host material and a compound [25] as a dopant material were vapor-deposited to a thickness of 35 nm so that the doping concentration was 2%. Next, as an electron transport material, E-1 shown below was laminated to a thickness of 20 nm. Next, after depositing 0.5 nm of lithium fluoride, 1000 nm of aluminum was vapor-deposited to form a cathode, and a 5 × 5 mm square device was fabricated. The film thickness here is a display value of a crystal oscillation type film thickness monitor. From this light-emitting element, high-efficiency blue light emission with a light emission efficiency of 3.0 cd / A was obtained. When this light emitting device was DC-driven at 10 mA / cm ² , the luminance half time was 7000 hours.

Comparative Example 1
A light emitting device was produced in the same manner as in Example 2 except that D-1 shown in the following formula was used as the dopant material. When this light emitting element was DC-driven at 10 mA / cm ² , blue light emission with a luminous efficiency of 1.6 cd / A was obtained. When this light emitting device was continuously driven with a direct current of 10 mA / cm ² , the luminance was reduced by half in 1000 hours.

Comparative Example 2
A light emitting device was produced in the same manner as in Comparative Example 1 except that D-2 shown below was used as the dopant material. When this light-emitting element was DC-driven at 10 mA / cm ² , blue light emission with a light emission efficiency of 2.3 cd / A was obtained. When this light emitting device was continuously driven with a direct current of 10 mA / cm ² , the luminance was reduced by half in 800 hours.

Example 3
A light emitting device was produced in the same manner as in Example 2 except that H-2 shown by the following formula was used as the host material. When this light-emitting element was DC-driven at 10 mA / cm ² , high-efficiency blue light emission with a light emission efficiency of 2.9 cd / A was obtained. When this light emitting device was continuously driven at a direct current of 10 mA / cm ² , the luminance half time was 4000 hours.

Example 4
A light emitting device was produced in the same manner as in Example 2 except that E-2 represented by the following formula was used as the electron transport material. When this light-emitting element was DC-driven at 10 mA / cm ² , high-efficiency blue light emission with a light emission efficiency of 2.5 cd / A was obtained. When this light emitting element was DC-driven at 10 mA / cm ² , the luminance half time was 4000 hours.

Example 5
After vapor-depositing H-1 as a host material and compound [25] as a dopant material to a thickness of 5 nm so as to have a doping concentration of 2%, H-1 as a host material is further used as the light-emitting material. A light emitting device was produced in the same manner as in Example 2 except that 5,6,11,12-tetraphenylnaphthacene was laminated as a dopant material to a thickness of 30 nm so that the doping concentration was 1%. From this light-emitting element, high-efficiency white light emission with a light emission efficiency of 7.0 cd / A was obtained. When this light emitting device was DC-driven at 10 mA / cm ² , the luminance half time was 5000 hours.

Example 6
A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam evaporated product) on which an ITO transparent conductive film is deposited to 150 nm is cut into 30 × 40 mm, and a 300 μm pitch (remaining width 270 μm) × 32 pieces is obtained by photolithography. Patterned into stripes. One side of the ITO stripe in the long side direction is expanded to a pitch of 1.27 mm (opening width 800 μm) in order to facilitate electrical connection with the outside. The obtained substrate was ultrasonically washed with acetone and “Semicocrine 56” (manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes, respectively, and then washed with ultrapure water. Subsequently, it was ultrasonically cleaned with isopropyl alcohol for 15 minutes and then immersed in hot methanol for 15 minutes and dried. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl was deposited as a hole transport material by a resistance heating method to a thickness of 150 nm. Next, H-6 as a host material and compound [25] as a dopant material were vapor-deposited to a thickness of 35 nm so that the doping concentration was 2%. Next, E-1 was laminated to a thickness of 20 nm as an electron transport material. The film thickness referred to here is a crystal oscillation type film thickness monitor display value. Next, the mask provided with 16 250 μm openings (corresponding to the remaining width of 50 μm and 300 μm pitch) by wet etching on a 50 μm thick Kovar plate was replaced with a mask so as to be orthogonal to the ITO stripe in vacuum, It fixed with the magnet from the back surface so that a mask and an ITO board | substrate might closely_contact | adhere. Then, after 0.5 nm of lithium fluoride was deposited, 200 nm of aluminum was deposited to prepare a 32 × 16 dot matrix element. When this element was driven in matrix, characters could be displayed without crosstalk.

Claims (7)

A light emitting device material comprising a pyrene compound represented by the general formula (1).

(R ^{1 to} R ¹⁵ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl In a condensed ring formed between a thioether group, aryl group, heteroaryl group, halogen, cyano group, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, phosphine oxide group, and adjacent substituents Provided that at least one of R ^{1 to} R ¹⁰ is single-bonded to A. Y ¹ to Y ⁵ are selected from nitrogen and carbon atoms, provided that Y ^{1 to} Y ⁵ are selected. at least one is a nitrogen atom, is R ¹¹ to R ¹⁵ is present Do a substituent on the nitrogen atom in the case of nitrogen atoms .) The light emitting device material according to claim 1, wherein A is single-bonded with at least one of R ¹ , R ³ , R ⁶ , and R ⁸ . The light emitting device material according to claim 1, wherein at least one of Y ^{1 to} Y ⁵ is a nitrogen atom. A light emitting device comprising at least a light emitting layer between an anode and a cathode and emitting light by electric energy, wherein the light emitting device contains the light emitting device material according to claim 1. The light emitting device according to claim 4, wherein the light emitting layer contains a light emitting device material represented by the general formula (1). The light emitting element according to claim 4, wherein the light emitting layer has a host material and a dopant material, and the light emitting element material represented by the general formula (1) is used as the dopant material. There is at least an electron transport layer between the light emitting layer and the cathode, the electron transport layer contains electron-accepting nitrogen, and is further composed of a heterogeneous element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus. The light emitting device according to claim 4, comprising a compound having an aryl ring structure.