JP2000328052A - Organic electroluminescent device material and organic electroluminescent device using the same - Google Patents

Abstract

(57) [Abstract] [Object] To provide an organic EL device which emits light from yellow to red, has higher luminous efficiency and higher luminance than conventional ones, and has a long luminous life. A material for an organic electroluminescent device comprising a monocyclic compound or a condensed polycyclic compound having two or more substituents represented by the following general formula [1]. General formula [1]

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting material for an organic electroluminescence (EL) device used for a flat light source or display and a light emitting device having a high luminance.

[0002]

2. Description of the Related Art An EL device using an organic substance is expected to be used as an inexpensive, large-area, full-color display device of a solid light emitting type, and many developments have been made. Generally, an EL element includes a light-emitting layer and a pair of opposed electrodes sandwiching the light-emitting layer. In light emission, when an electric field is applied between both electrodes, electrons are injected from the cathode side, holes are injected from the anode side, the electrons recombine with holes in the light emitting layer, and the energy level is changed from the conduction band. This is a phenomenon in which energy is emitted as light when returning to the valence band.

[0003] Conventional organic EL devices have a higher driving voltage and lower luminous brightness and luminous efficiency than inorganic EL devices.
In addition, the characteristic deterioration was remarkable, and it had not been put to practical use.
2. Description of the Related Art In recent years, an organic EL in which a thin film containing an organic compound having high fluorescence quantum efficiency that emits light at a low voltage of 10 V or less is laminated.
Devices have been reported and are of interest (see Applied Physics Letters, vol. 51, p. 913, 1987). This method uses a metal chelate complex for a light emitting layer and an amine compound for a hole injection layer to obtain high-intensity green light emission.
d / m ² and maximum luminous efficiency of 1.5 lm / W,
Has performance close to the practical range.

[0004] However, organic EL devices up to the present have been improved in light emission luminance due to an improved configuration, but do not yet have sufficient light emission luminance. In addition, there is a major problem that the stability upon repeated use is poor. This is because, for example, a metal chelate complex such as a tris (8-hydroxyquinolinato) aluminum complex is chemically unstable during electroluminescence, has poor adhesion to a cathode, and is greatly deteriorated by short-time light emission. I was For the above reasons, in order to develop an organic EL device having high luminous luminance and luminous efficiency and excellent stability in repeated use, development of a durable luminescent material having excellent luminous ability has been required. Is desired.

[0005]

An object of the present invention is to provide a light emitting material for an organic EL device having a light emission color from yellow to red, having a high light emission luminance and a long light emission life, and an organic EL device using the same. is there. As a result of intensive studies by the present inventors, it has two or more substituents represented by the general formula [1].
An organic EL device using a light-emitting material for an organic EL device composed of a monocyclic compound or a condensed polycyclic compound, the organic EL device using the light-emitting layer emits yellow to red light, has high emission luminance and emission efficiency, and has an excellent emission life. I found it.

[0006]

The present invention relates to a material for an organic electroluminescent device comprising a monocyclic compound or a condensed polycyclic compound having two or more substituents represented by the following general formula [1]. General formula [1]

[0007]

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[Wherein, R ¹ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and A represents an oxygen atom or a methylene group represented by the general formula [2]. And B represents an oxygen atom or a sulfur atom. General formula [2]

[0009]

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[Wherein R ² and R ³ each independently represent a substituent selected from the group consisting of a hydrogen atom, a cyano group, a halogen atom, an alkylcarbonyl group, and an alkoxycarbonyl group. It will not be. However, R ² and R ³ may be combined with each other to be integrated. Further, the present invention provides a compound represented by the following general formula [3]:
The organic electroluminescent device material described above, comprising a monocyclic compound or a condensed polycyclic compound having at least one compound. General formula [3]

[0011]

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[In the formula, R ⁴ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. The organic electroluminescent device according to claim 1, wherein a part or all of a portion of the monocyclic compound or the condensed polycyclic compound other than the general formula [1] is electron-donating. Material.

The present invention also relates to a monocyclic compound or a condensed polycyclic compound, wherein a part or all of a portion excluding the general formula [1] is a partial structure represented by the following general formula [4] or [5]: The material for an organic electroluminescence device, wherein the material includes a formula. General formula [4]

[0014]

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The general formula [5]

[0016]

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[Wherein R ⁵ and R ⁶ represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and X represents a direct bond, a divalent substituted or unsubstituted group. Represents an alkyl group, a substituted or unsubstituted aryl group, an oxygen atom, a nitrogen atom, a sulfur atom, a substituted or unsubstituted nitrogen atom, a carbonyl group, or a thiocarbonyl group. Further, according to the present invention, in an organic electroluminescent element formed by forming a light emitting layer or a plurality of organic compound thin films including a light emitting layer between a pair of electrodes, any one of the layers may be made of the material for the organic electroluminescent element alone. Alternatively, the organic electroluminescence device is characterized by being contained as a mixture.

The present invention also relates to an organic electroluminescence device comprising a light-emitting layer or a plurality of organic compound thin films including the light-emitting layer formed between a pair of electrodes, wherein the light-emitting layer is made of the organic electroluminescence device material alone or An organic electroluminescent device characterized by being contained as a mixture.

Further, the present invention is the above-described organic electroluminescence device, wherein a hole injection layer is formed between the anode and the light emitting layer.

The present invention also relates to the above organic electroluminescent device, wherein the hole injection layer is a layer containing at least one selected from the group consisting of an arylamine derivative, a phthalocyanine compound and a triphenylene derivative. is there.

Further, the present invention is the above-described organic electroluminescence device, wherein an electron injection layer is formed between the cathode and the light emitting layer.

The present invention also provides the organic electroluminescence device, wherein the electron injection layer is a layer containing at least one selected from the group consisting of a metal complex compound and a nitrogen-containing aromatic ring compound.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The material for an organic electroluminescence device of the present invention comprises a monocyclic compound or a condensed polycyclic compound having two or more substituents represented by the general formula [1]. This compound has a substituent A represented by the general formula [1]:
Is an electron-attracting property, so that it absorbs on the long wavelength side, and further, a moiety other than the general formula [1] has an electron-donating property as represented by the general formula [4] or [5]. If there is, it absorbs effectively on the long wavelength side. This is described in detail in Color Science (see Color and Chemical Structure of Dyes, by Maruzen Co., Ltd., Mitsuhiko Hida).

Here, the portion excluding the general formula [1] from the monocyclic compound or the condensed polycyclic compound used in the present invention is:
2 to 15 valent monocyclic group, 2 to 15 valent condensed polycyclic group, or aromatic ring structural unit 2-1 containing a monocyclic or condensed polycyclic ring
Five are divalent to divalent groups bonded directly or via a non-aromatic ring structural unit consisting of carbon, hydrogen, oxygen, nitrogen and sulfur atoms.

The term "electron-withdrawing group" as used herein refers to an atomic group that attracts electrons from a partner due to a resonance effect or an induced effect in an electron theory, and a group that gives an electron thereto is referred to as an electron-donating group ("Rikken Dictionary" published by Iwanami Shoten). ).)

The nitro group of nitrobenzene is a typical electron-withdrawing group, which attracts electrons from the benzene nucleus by adding the resonance effect of its structure and the effect of inducing nitrogen atoms. Due to the electron-withdrawing properties of the nitro group, nitrobenzene has a larger dipole moment than expected simply from the polarity of the nitro group, shows a strong absorption band in the near ultraviolet, and It has properties such that the meta position is more responsive to the substitution than the ortho or para position. In addition, a nitroso group, a carbonyl group, a carboxyl group, a nitrile group, and the like have similar properties.

On the other hand, in the case of -NH _{2 of} aniline, the resonance effect of the structure has a function of an electron donating group, and the effect of inducing a nitrogen atom has a function of an electron withdrawing group.
The amino group of aniline is an electron donating group because the previous effect is superior. The situation is exactly the same for the hydroxyl group of phenol. In electron donating groups, ortho-para orientation is observed upon substitution of benzene by an electrophile. On the other hand, a phenyl group is an electron donating group in the case of nitrobenzene, but functions as an electron withdrawing group in the case of aniline or phenol.

Representative examples of the electron donating group include a substituted or unsubstituted amino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkyl group and an aryl group. is not.

The monocyclic compound used in the present invention includes:
There is a compound containing a monocyclic group such as a monocyclic cycloalkyl group, a monocyclic aryl group, or a monocyclic heterocyclic group. These may be substituted.

The monocyclic cycloalkyl group is a cycloalkyl group having 4 to 8 carbon atoms such as a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclohexenyl group, a cycloheptyl group and a cyclooctyl group.

The monocyclic aryl group includes a phenyl group.

Examples of the monocyclic heterocyclic group include a thienyl group, a thiophenyl group, a furyl group, a pyrrolyl group, an imidazolyl group,
Examples include a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a triazolyl group, an oxazolyl group, a thiazolyl group, an oxadiazolyl group, a thiadiazolyl group, and an imidadiazolyl group.

Examples of the condensed polycyclic compound used in the present invention include compounds containing a condensed polycyclic group such as a condensed polycyclic aryl group, a condensed polycyclic heterocyclic group or a condensed polycyclic cycloalkyl group. These may be substituted.

Examples of the compound containing a condensed polycyclic cycloalkyl group include decalin.

Compounds containing a condensed polycyclic aryl group include naphthalene, anthracene, phenanthrene, fluorene, pyrene, chrysene, naphthacene, perylene, azulene, fluorenone, anthraquinone, dibenzosuberenone, tetracyanoquinodimethane, coronene, rubicene, Dekacyclene, acenaphthene, triphenylene and the like can be mentioned.

Compounds containing a fused polycyclic heterocyclic group include:
Indole, quinoline, isoquinoline, carbazole,
Acridine, thioxanthone, coumarin, acridone,
Diphenylene sulfone, quinoxaline, benzothiazole, phenazine, phenanthroline, phenothiazine,
Quinacridone, flavanthrone, indanthrone and the like. Other fused polycyclic groups include a 1-tetralyl group, a 2-tetralyl group, a tetrahydroquinolyl group, and the like.

Further, as the monocyclic compound or the condensed polycyclic compound of the present invention, a compound containing a divalent to pentavalent group in which the above-mentioned monocyclic group or condensed polycyclic group is directly linked can be mentioned.

Further, the monocyclic group or the condensed polycyclic group of the present invention may be connected to a non-cyclic structural unit consisting of a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom and a sulfur atom.
There are compounds containing a valence group.

The acyclic structural unit consisting of a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom and a sulfur atom is divalent or higher and is linear or branched. Preferably, the number of atoms is 1
~ 40. Examples of the acyclic structural unit include divalent or higher valent residues such as an alkyl group, an alkylene group, an alkyloxy group, an alkylthio group, an amino group and an alkylamino group, in addition to an oxygen atom and a sulfur atom.

When the monocyclic compound or the condensed polycyclic compound is formed by linking the monocyclic group or the condensed polycyclic group directly or via a non-cyclic structural unit, the number of the monocyclic group or the condensed polycyclic group is The number is 2 to 10, and it may be possible to bond at two or more places. Further, there may be a bond between a monocyclic group and a fused ring group.

Specifically, examples of a monocyclic group or a condensed polycyclic group directly bonded to each other include binaphthyl, biquinoline,
Flavone, phenyltriazine, bisbenzothiazole, bithiophene, phenylbenzotriazole, phenylbenzimidazole, phenylacridine, bis (benzoxazolyl) thiophene, bis (phenyloxazolyl) benzene, biphenylylphenyloxadiazole, diphenylbenzoquinone, Examples include compounds having a skeleton of diphenylisobenzofuran, diphenylpyridine, stilbene, dibenzyl, diphenylmethane, bis (phenylisopropyl) benzene, diphenylfluorene, and diphenylhexafluoropropane.

Examples of a monocyclic group or a condensed polycyclic group bonded via a non-aromatic ring structural unit include dibenzylnaphthyl ketone, dibenzylidenecyclohexanone, distyrylnaphthalene, (phenylethyl) benzylnaphthalene, diphenylether, Methyldiphenylamine, benzophenone, phenyl benzoate, diphenylurea, diphenyl sulfide, diphenyl sulfone, diphenoxybiphenyl, bis (phenoxyphenyl) sulfone,
Compounds having a skeleton of bis (phenoxyphenyl) propane, diphenoxybenzene, ethylene glycol diphenyl ether, neopentyl glycol diphenyl ether, dipicolylamine, dipyridylamine are exemplified.

The partial structural formula of the monocyclic compound or the condensed polycyclic compound of the present invention except for the general formula [1] is preferably an electron-donating substituent. In particular, those containing a nitrogen atom,
From the viewpoint of synthesis, a partial structural formula represented by the general formula [4] or the general formula [5] is preferable. R ⁵ and R ⁶ in the general formula [4] or the general formula [5] represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and X represents a direct bond or a divalent substituent. Or an unsubstituted alkyl group, substituted or unsubstituted aryl group, oxygen atom, nitrogen atom, sulfur atom, substituted or unsubstituted nitrogen atom, carbonyl group, and thiocarbonyl group.

The alkyl group and the aryl group may be the same as those described later for the alkyl group and the aryl group of R ¹ .

In the following, typical examples of the partial structural formulas obtained by removing the general formula [1] from the monocyclic compound or the condensed polycyclic compound of the present invention are specifically shown in Table 1. It is not limited to a representative example.

[0046]

[Table 1]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

In the present invention, a hydrogen atom, a substituted or unsubstituted alkyl group, a substituent represented by the general formula [1],
Or a substituted or unsubstituted aryl group, A represents an oxygen atom or a methylene group represented by the general formula [2], and B represents an oxygen atom or a sulfur atom.

The substituted or unsubstituted aryl group includes the substituted or unsubstituted monocyclic group and the substituted or unsubstituted fused polycyclic group.

As a specific example of the substituted or unsubstituted alkyl group, the substituted or unsubstituted alkyl group is
Methyl group, ethyl group, propyl group, butyl group, sec-
Butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, stearyl group, 2-phenylisopropyl group, trichloromethyl group, trifluoromethyl group, benzyl group, α-phenoxybenzyl group,
Substitution of alkyl groups having 1 to 30 carbon atoms such as α, α-dimethylbenzyl group, α, α-methylphenylbenzyl group, α, α-ditrifluoromethylbenzyl group, triphenylmethyl group and α-benzyloxybenzyl group There are groups.

From the viewpoint of synthesis, R ¹ is preferably an alkyl group, particularly an alkyl group having 1 to 3 carbon atoms.

In the present invention, R ² and R ³ in the partial structural formula represented by the general formula [2] each independently represent a hydrogen atom,
A substituent is represented by a group selected from a cyano group, a halogen atom, an alkylcarbonyl group, and an alkoxycarbonyl group, but is not simultaneously a hydrogen atom. Where R
² and R ³ may be combined with each other to be integrated.

Here, the alkylcarbonyl group and the alkyl group of the alkoxycarbonyl group are the same as those exemplified in the description of R ¹ .

Examples of the halogen atom include fluorine, chlorine, bromine and iodine.

Specific examples of the general formula [2] include a cyanochloromethylene group, a bromocyanomethylene group, a cyano (methoxycarbonyl) methylene group, a chloro (methoxycarbonyl) methylene group, and a bromo (ethoxycarbonyl) methylene group. Preferred examples include dicyanomethylene, cyanomethylene, di (methylcarbonyl) methylene, and di (methoxycarbonyl) methylene.

A preferred example of the compound represented by the general formula [1] is a partial structural formula represented by the general formula [3]. Here, R ⁴ in the general formula [3] is the same as that exemplified in the description of R ¹ .

The compound of the present invention has, within its molecule,
The portion A of the substituent represented by the general formula [1] is electron-withdrawing, has absorption on the long wavelength side, and has strong fluorescence in an individual, so that it is useful as a red fluorescent material. And,
Since the glass transition point and melting point are high, the resistance (heat resistance) to Joule heat generated in the organic layer, between the organic layers, or between the organic layer and the metal electrode during electroluminescence is improved.
When used as an organic EL device material, it exhibits high light emission luminance and is advantageous when emitting light for a long time. When the site represented by the general formulas [4] to [5] is electron donating, the absorption wavelength is further increased to the longer wavelength side, which is useful.

A general method for synthesizing the compound of the present invention is shown below.

A formyl-substituted compound of the compound represented by the general formula [6] and a substituted or unsubstituted monocyclic compound or a substituted or unsubstituted condensed polycyclic compound is dehydrated in a high boiling alcohol with a base as a catalyst. By condensing, the target compound can be synthesized. As the high boiling point solvent, n-propanol, iso-propanol, n
-Butanol, tert-butanol, n-pentyl alcohol, iso-pentanol and the like. Bases include piperidine, DBU (diazabicycloundecene)
And the like. The above synthesis method is an example and is not particularly limited. General formula [6]

[0065]

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Wherein A, B, and R ¹ are respectively equivalent to A, B, and R ^{1 in} the general formula [1]. Hereinafter, typical examples of the compound of the present invention are specifically shown in Table 2, but the present invention is not limited to these typical examples.

[0067]

[Table 2]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

The compound of the present invention has strong fluorescence in a solid state and has excellent electroluminescence. In addition, since it has both excellent electron injecting property and electron transporting property from a metal electrode, it can be effectively used as a light emitting material, and further has another hole transporting material, an electron transporting material or Doping materials can be used.

An organic EL device is a device in which a single or multilayer organic thin film is formed between an anode and a cathode. In the case of a single layer type, a light emitting layer is provided between an anode and a cathode. The light-emitting layer contains a light-emitting material and may further contain a hole-injection material or an electron-injection material for transporting holes injected from an anode or electrons injected from a cathode to the light-emitting material. However, the luminescent material of the present invention
Since it has extremely high emission quantum efficiency, high hole transport ability and electron transport ability and can form a uniform thin film, it is possible to form a light emitting layer using only the light emitting material of the present invention. The multilayer type includes (anode / hole injection zone / light-emitting layer / cathode), (anode / light-emitting layer / electron injection zone / cathode),
(Anode / Hole injection zone / Emitting layer / Electron injection zone / Cathode)
There is an organic EL element stacked in a multilayer structure of the above. The compound of the present invention has high light-emitting properties, and has a hole-injecting property, a hole-transporting property and an electron-injecting property, and an electron-transporting property.
It can be used in a light emitting layer as a light emitting material.

In the light emitting layer, if necessary, in addition to the compound of the present invention, further known light emitting materials, doping materials, hole injection materials and electron injection materials can be used. When the organic EL element has a multilayer structure, it is possible to prevent a decrease in luminance and life due to quenching.
If necessary, a combination of a light emitting material, a doping material, a hole injection material, and an electron injection material can be used. Further, with the use of the doping material, emission luminance and emission efficiency can be improved, and red and blue light emission can be obtained. Also,
In the case of one layer, the hole injection zone and the electron injection zone have the same meaning as the hole injection layer and the electron injection layer, respectively. Each of the hole injection zone, the light emitting layer, and the electron injection zone may be formed by a layer structure of two or more layers. In that case, in the case of the hole injection zone, a layer for injecting holes from the electrode is a hole injection layer, and a layer for receiving holes from the hole injection layer and transporting holes to the light emitting layer is a hole transport layer. Call. Similarly, in the case of the electron injection zone, a layer that injects electrons from the electrode is called an electron injection layer, and a layer that receives electrons from the electron injection layer and transports electrons to the light emitting layer is called an electron transport layer. Each of these layers is selected and used depending on factors such as the energy level of the material, heat resistance, and adhesion to the organic layer or the metal electrode.

The light emitting material or doping material which can be used in the light emitting layer together with the compound of the present invention includes anthracene, naphthalene, phenanthrene, pyrene, tetracene, coronene, chrysene, fluorescein, perylene,
Phthaloperylene, naphthaloperylene, perinone, phthaloperinone, naphthaloperinone, diphenylbutadiene,
Tetraphenylbutadiene, coumarin, oxadiazole, aldazine, bisbenzoxazoline, bisstyryl, pyrazine, cyclopentadiene, quinoline metal complex, aminoquinoline metal complex, benzoquinoline metal complex, imine, diphenylethylene, vinylanthracene, diaminocarbazole, pyran Thiopyran, polymethine, merocyanine, imidazole chelated oxinoid compounds, quinacridone, rubrene, and fluorescent dyes for dye lasers and whitening, but are not limited thereto.

The main component of the compound of the present invention and any of the above compounds which can be used together in the light emitting layer may be present in the light emitting layer. That is, by the respective combinations of the above-mentioned compound and the compound of the present invention, the compound of the present invention can be used as a main material forming the light emitting layer or as a doping material into other main materials.

The hole injecting material has the ability to transport holes, has the effect of injecting holes from the anode, and has an excellent hole injecting effect on the light emitting layer or the light emitting material. Compounds that prevent excitons from migrating to an electron injection zone or an electron injection material and have excellent thin film forming ability can be used. Specifically, phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives, oxazole, oxadiazole, triazole, imidazole, imidazolone, imidazolethione, pyrazoline, pyrazolone,
Tetrahydroimidazole, oxazole, oxadiazole, hydrazone, acylhydrazone, polyarylalkane, stilbene, butadiene, benzidine-type triphenylamine, styrylamine-type triphenylamine, diamine-type triphenylamine, and derivatives thereof, and polyvinyl carbazole , Polysilane, and a polymer material such as a conductive polymer, but are not limited thereto.

Among the hole injecting materials that can be used in the organic EL device of the present invention, more effective hole injecting materials are
An arylamine derivative, a phthalocyanine compound or a triphenylene derivative. Specific examples of the arylamine derivative include triphenylamine, tolylamine, tolylphenylamine, N, N'-diphenyl-
N, N'-di-m-tolyl-4,4'-biphenyldiamine, N, N, N ', N'-tetra (p-tolyl) -p
-Phenylenediamine, N, N, N ', N'-tetra-
p-tolyl-4,4'-biphenyldiamine, N, N '
-Diphenyl-N, N'-di (1-naphthyl) -4,
4'-biphenyldiamine, N, N'-di (4-n-butylphenyl) -N, N'-di-p-tolyl-9,10
-Phenanthylenediamine, 4,4 ', 4 "-tris (N-phenyl-Nm-tolylamino) triphenylamine, 1,1-bis [4- (di-p-tolylamino)
[Phenyl] cyclohexane and the like, or oligomers or polymers having an aromatic tertiary amine skeleton, but are not limited thereto.

Specific examples of the phthalocyanine (Pc) compound include H ₂ Pc, CuPc, CoPc, NiPc, Z
nPc, PdPc, FePc, MnPc, ClAlP
c, ClGaPc, ClInPc, ClSnPc, Cl
₂ SiPc, (HO) AlPc, (HO) GaPc, V
OPc, TiOPc, MoOPc, GaPc-O-Ga
Examples include, but are not limited to, phthalocyanine derivatives such as Pc and naphthalocyanine derivatives.

Specific examples of the triphenylene derivative include:
Hexaalkoxytriphenylenes such as hexamethoxytriphenylene, hexaethoxytriphenylene, hexahexyloxytriphenylene, hexabenzyloxytriphenylene, trimethylenedioxytriphenylene, triethylenedioxytriphenylene, hexaphenoxytriphenylene, hexanaphthyloxytriphenylene, hexabiphenylyloxytriphenylene ,
Examples include, but are not limited to, hexaaryloxytriphenylenes such as triphenylenedioxytriphenylene, hexaacyloxytriphenylenes such as hexaacetoxytriphenylene and hexabenzoyloxytriphenylene.

The electron injecting material has the ability to transport electrons, has the effect of injecting holes from the cathode, and has an excellent effect of injecting electrons into the light emitting layer or the light emitting material. Compounds that prevent migration to the hole injection zone and have excellent thin film forming ability can be mentioned. For example, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxazole, oxadiazole,
Triazole, imidazole, perylenetetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane,
Examples include, but are not limited to, anthrones and derivatives thereof. In addition, sensitization can be performed by adding an electron accepting substance to the hole injecting material and adding an electron donating substance to the electron injecting material.

In the organic EL device of the present invention, a more effective electron injection material is a metal complex compound or a nitrogen-containing five-membered ring derivative. Specifically, as the metal complex compound, lithium 8-hydroxyquinolinate, bis (8
-Hydroxyquinolinato) zinc, bis (8-hydroxyquinolinato) copper, bis (8-hydroxyquinolinato) manganese, tris (8-hydroxyquinolinato)
Aluminum, tris (2-methyl-8-hydroxyquinolinato) aluminum, tris (8-hydroxyquinolinato) gallium, bis (10-hydroxybenzo [h] quinolinato) beryllium, bis (10-hydroxybenzo [h] (Quinolinato) zinc, bis (2-methyl-8-hydroxyquinolinato) chlorogallium, bis (2-methyl-8-hydroxyquinolinate) (o-
Cresolate) gallium, bis (2-methyl-8-hydroxyquinolinate) (1-naphtholate) aluminum, bis (2-methyl-8-hydroxyquinolinate)
(2-naphtholate) gallium, bis (2-methyl-8
-Hydroxyquinolinato) phenolate gallium, bis (o- (2-benzoxazolyl) phenolate) zinc, bis (o- (2-benzothiazolyl) phenolate) zinc, bis (o- (2-benzotriazolyl) ) Phenolates) zinc and the like, but are not limited thereto. As the nitrogen-containing five-membered derivative, an oxazole, thiazole, oxadiazole, thiadiazole or triazole derivative is preferable. In particular,
2,5-bis (1-phenyl) -1,3,4-oxazole, dimethyl POPOP, 2,5-bis (1-phenyl) -1,3,4-thiazole, 2,5-bis (1-phenyl) ) -1,3,4-oxadiazole, 2- (4 ′
-Tert-butylphenyl) -5- (4 "-biphenyl) -1,3,4-oxadiazole, 2,5-bis (1-naphthyl) -1,3,4-oxadiazole,
1,4-bis [2- (5-phenyloxadiazolyl)]
Benzene, 1,4-bis [2- (5-phenyloxadiazolyl) -4-tert-butylbenzene], 2-
(4′-tert-butylphenyl) -5- (4 ″ -biphenyl) -1,3,4-thiadiazole, 2,5-bis (1-naphthyl) -1,3,4-thiadiazole,
1,4-bis [2- (5-phenylthiadiazolyl)] benzene, 2- (4′-tert-butylphenyl) -5
-(4 "-biphenyl) -1,3,4-triazole,
Examples include, but are not limited to, 2,5-bis (1-naphthyl) -1,3,4-triazole, 1,4-bis [2- (5-phenyltriazolyl)] benzene. .

In the present organic EL device, the light emitting layer contains
In addition to the compound of the present invention, at least one of a light emitting material, a doping material, a hole injection material, and an electron injection material may be contained in the same layer. In order to improve the stability of the organic EL device obtained according to the present invention with respect to temperature, humidity, atmosphere, and the like, a protective layer may be provided on the surface of the device, or the entire device may be protected with silicon oil, resin, or the like. Is also possible.

As the conductive material used for the anode of the organic EL device, those having a work function of more than 4 eV are suitable, and carbon, aluminum, vanadium, iron, cobalt, nickel, tungsten, silver, gold, platinum , Palladium and their alloys, tin oxide used for ITO substrate, NESA substrate, metal oxide such as indium oxide,
Further, an organic conductive resin such as polythiophene or polypyrrole is used.

As the conductive material used for the cathode, 4
Suitable are those having a work function lower than eV, such as, but not limited to, magnesium, calcium, tin, lead, titanium, yttrium, lithium, ruthenium, manganese, aluminum, and alloys thereof. . Alloys include magnesium / silver,
Representative examples include magnesium / indium and lithium / aluminum, but are not limited thereto. The ratio of the alloy is controlled by the temperature, atmosphere, degree of vacuum, and the like of the evaporation source, and is selected to be an appropriate ratio. The anode and the cathode may be formed by two or more layers if necessary.

In the organic EL device, at least one of them is desirably sufficiently transparent in the emission wavelength region of the device in order to emit light efficiently. Further, it is desirable that the substrate is also transparent. The transparent electrode is set using the above-described conductive material so as to secure a predetermined translucency by a method such as vapor deposition or sputtering. The electrode on the light emitting surface desirably has a light transmittance of 10% or more. The substrate is not limited as long as it has mechanical and thermal strength and transparency, but, for example, a glass substrate, a polyethylene plate, a polyethylene terephthalate plate, a polyether sulfone plate, A transparent resin such as a polypropylene plate can be used.

The layers of the organic EL device according to the present invention can be formed by any of dry film forming methods such as vacuum evaporation, sputtering, plasma, and ion plating, and wet film forming methods such as spin coating, dipping and flow coating. Can be applied. The film thickness is not particularly limited, but needs to be set to an appropriate film thickness. If the film thickness is too large, a large applied voltage is required to obtain a constant light output, resulting in poor efficiency. If the film thickness is too small, pinholes and the like are generated, and sufficient light emission luminance cannot be obtained even when an electric field is applied. The normal film thickness is suitably in the range of 5 nm to 10 μm, but is more preferably in the range of 10 nm to 0.2 μm.

In the case of the wet film forming method, the material forming each layer is made of ethanol, chloroform, tetrahydrofuran,
The thin film is formed by dissolving or dispersing in a suitable solvent such as dioxane, and any solvent may be used. In any of the organic thin film layers, a suitable resin or additive may be used for improving film forming properties, preventing pinholes in the film, and the like. Examples of usable resins include insulating resins such as polystyrene, polycarbonate, polyarylate, polyester, polyamide, polyurethane, polysulfone, polymethyl methacrylate, polymethyl acrylate, and cellulose, and copolymers thereof, and poly-N-vinyl. Examples thereof include photoconductive resins such as carbazole and polysilane, and conductive resins such as polythiophene and polypyrrole. Examples of the additive include an antioxidant, an ultraviolet absorber, and a plasticizer.

As described above, by using the compound of the present invention in the light emitting layer of the organic EL device, it was possible to improve the characteristics of the organic EL device such as the luminous efficiency and the maximum emission luminance. In addition, this device is extremely stable against heat and current, and furthermore, it can emit light that can be practically used at a low driving voltage, so that the deterioration, which has been a major problem until now, can be significantly reduced. Was completed.

The organic EL device of the present invention can be used as a flat panel display such as a wall-mounted television or a flat luminous body.
It can be applied to light sources such as copiers and printers, light sources such as liquid crystal displays and instruments, display boards, and sign lamps, and its industrial value is extremely large.

The material of the present invention can be used in the fields of organic EL devices, electrophotographic photosensitive members, photoelectric conversion devices, solar cells, image sensors and the like.

[0100]

The present invention will be described in more detail with reference to the following examples. Method for synthesizing compound (1) In 50 ml of isopropyl alcohol, 8 g of 4-dicyanomethylene-2,6-dimethyl-4H-pyrazine,
3 g of 4-diformylbenzene and 8 g of piperidine are added,
The mixture was heated and stirred at 90 ° C. for 10 hours. Thereafter, the mixture was diluted with 100 ml of methanol, and the precipitated yellow solid was separated by suction filtration, dried, and purified by column chromatography using silica gel to obtain 2 g of yellow fluorescent powder.
I got It was confirmed to be Compound (1) by analysis of molecular weight analysis, NMR spectrum and the like by FD-MS. Synthesis method of compound (8) 8 g of 4-dicyanomethylene-2,6-dimethyl-4H-pyrazine, N-ethylcarbazole-3,6-dicarboxaldehyde 4 in 50 ml of n-butyl alcohol
g and 8 g of piperidine, and the mixture was heated and stirred at 90 ° C. for 10 hours. Thereafter, the mixture was diluted with 100 ml of methanol, and the precipitated red solid was separated by suction filtration, dried, and purified by column chromatography using silica gel to obtain 2 g of a powder having red fluorescence. It was confirmed to be Compound (8) by analysis of molecular weight analysis, NMR spectrum and the like by FD-MS. FIG. 1 shows the infrared absorption spectrum (KBr tablet method) of this compound. Synthesis method of compound (16) In 50 ml of n-butyl alcohol, 6 g of 4-dicyanomethylene-2,6-dimethyl-4H-pyrazine, 2 g of tris (4-formyl-phenyl) amine and piperidine 8
g was added and stirred at 90 ° C. for 10 hours. Then 1
The mixture was diluted with 00 ml of methanol, and the precipitated red solid was filtered off with suction, dried and purified by column chromatography using silica gel to obtain 2 g of a powder having red fluorescence. Molecular weight analysis by FD-MS, NMR
Analysis of the spectrum and the like confirmed that the product was Compound (16).

Hereinafter, Examples using the compound of the present invention will be described. In this example, characteristics of an organic EL element having an electrode area of 2 mm × 2 mm were measured.

Example 1 A compound (1) shown in Table 1 and 2,5-bis (1-naphthyl)-as a luminescent material were placed on a washed glass plate with an ITO electrode.
1,2,10: 1,3,4-oxadiazole, polycarbonate resin (Teijin Chemical: Panlite K-1300)
Was dissolved in tetrahydrofuran at a weight ratio of, and a light-emitting layer having a thickness of 100 nm was obtained by spin coating. An electrode having a thickness of 150 nm was formed thereon with an alloy of magnesium and silver mixed at a ratio of 10: 1 to obtain an organic EL device. The light emission characteristics of this element are such that the light emission luminance at a DC voltage of 5 V is 60.
(Cd / m ² ), maximum emission luminance 1500 (cd / m ² ),
Yellow luminescence with a luminous efficiency of 0.20 (lm / W) was obtained.

Example 2 On a cleaned glass plate with an ITO electrode, N, N '-(3
-Methylphenyl) -N, N'-diphenyl-1,1 '
-Biphenyl-4,4'-diamine (TPD) was vacuum-deposited to obtain a 20-nm-thick hole injection layer. Next, the compound (8) was vapor-deposited to form a light-emitting layer having a thickness of 40 nm, and then a tris (8-hydroxyquinolinato) aluminum complex (Alq3) was vapor-deposited to obtain a 30-nm-thick electron injection layer. An electrode having a thickness of 100 nm was formed thereon using an alloy in which magnesium and silver were mixed at a ratio of 10: 1 to obtain an organic EL device. The hole injection layer and the light emitting layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device has a light emission luminance of 120 (cd / m ² ) at a DC voltage of 5 V, a maximum light emission luminance of 9500 (cd / m ² ), and a light emission efficiency of 1.0.
(Lm / W) red-orange emission was obtained.

Example 3 A compound (8) was dissolved in methylene chloride on a washed glass plate with an ITO electrode, and a hole injection type light emitting layer having a thickness of 50 nm was obtained by a spin coating method. Next, bis (2-methyl-8-hydroxyquinolinate) (1-naphtholate) gallium complex was vacuum-deposited to a thickness of 40 nm.
An electron injection layer was formed, and an electrode having a thickness of 100 nm was formed on the electron injection layer using an alloy in which magnesium and silver were mixed at a ratio of 10: 1 to obtain an organic EL device. The light emitting layer and the electron injection layer are 1
Vapor deposition was performed at a substrate temperature of room temperature in a vacuum of 0 ^-6 Torr. This device has an emission luminance of 150 at a DC voltage of 5 V.
(Cd / m ² ), maximum emission luminance 5200 (cd / m ² ),
Red-orange light emission with a light emission efficiency of 0.30 (lm / W) was obtained.

Example 4 Compound (16) was placed on a washed glass plate with an ITO electrode.
Was vacuum-deposited to obtain a hole-injection type light-emitting layer having a thickness of 50 nm. Next, a bis (2-methyl-8-hydroxyquinolinato) (phenolate) gallium complex was vacuum-deposited to form an electron injection layer having a thickness of 30 nm, and magnesium and silver were mixed at a ratio of 10: 1. 100 nm thick with alloy
Was formed to obtain an organic EL device. The light emitting layer and the electron injection layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device has a light emission luminance of 250 (cd / m ² ) at a DC voltage of 5 V and a maximum light emission luminance of 8200 (c / m ² ).
d / m ² ), and orange luminescence with a luminous efficiency of 0.6 (lm / W) was obtained.

Examples 5 to 14 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) was vacuum-deposited on a washed glass plate with an ITO electrode. A hole injection layer having a thickness of 30 nm was formed. Next, the compounds shown in Table 1 were vacuum-deposited as light-emitting materials to obtain a light-emitting layer having a thickness of 30 nm. Then, bis (2-methyl-8-hydroxyquinolinate)
(Phenolate) gallium complex is vacuum deposited to a thickness of 30
An electron injection layer having a thickness of 100 nm was formed, and an electrode having a thickness of 100 nm was formed on the electron injection layer using an alloy in which magnesium and silver were mixed at a ratio of 10: 1 to obtain an organic EL device. The hole injection layer and the light emitting layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. Table 3 shows the emission characteristics of this device. The emission luminance here is the luminance when a DC voltage of 5 V is applied. All of the organic EL elements of this example had a maximum luminance of 10,000 (cd /
m ² ) or higher, and emission colors from yellow to red could be obtained.

[0107]

[Table 3]

Example 15 4,4 ′, 4 ″ was placed on a washed glass plate with ITO electrodes.
-Tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine was vacuum deposited to a film thickness of 40
As a result, a hole injection layer having a thickness of nm was obtained. Next, α-NPD was vacuum-deposited to obtain a 10-nm-thick second hole injection layer. Further, a compound (8) is vacuum-deposited to form a light-emitting layer having a thickness of 30 nm, and a bis (2-methyl-8-hydroxyquinolinate) (1-phenolate) gallium complex is further vacuum-deposited to form a film. An electron injection layer having a thickness of 30 nm was formed, and an electrode having a thickness of 150 nm was formed thereon using an alloy in which aluminum and lithium were mixed at a ratio of 25: 1 to obtain an organic EL device. The hole injection layer and the light emitting layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device has a light emission luminance of 310 (cd / m ² ) at a DC voltage of 5 V, a maximum light emission luminance of 13000 (cd / m ² ), and a light emission efficiency of 1.2 (l).
m / W).

Example 16 An organic EL device was manufactured in the same manner as in Example 3, except that a hole injection layer of copper phthalocyanine having a thickness of 5 nm was provided between the ITO electrode and the compound (8). This device has a light emission luminance of 400 (cd / m ² ) at a DC voltage of 5 V, a maximum light emission luminance of 12000 (cd / m ² ), and a light emission efficiency of 1.4 (lm).
/ W).

Example 17 4,4 ′, 4 ″ -Tris [N- (3-methylphenyl)
An organic EL device was produced in the same manner as in Example 15 except that a hole injection layer of metal-free phthalocyanine having a thickness of 20 nm was provided instead of [-N-phenylamino] triphenylamine. This device has an emission luminance of 25 at a DC voltage of 5 V.
0 (cd / m ² ), maximum light emission luminance 12000 (cd / m ² )
m ² ), and orange luminescence with a luminous efficiency of 1.1 (lm / W) was obtained.

Example 18 The compound (2): α-NPD was used as a light emitting layer at a ratio of 1: 100.
Except that a thin film having a thickness of 30 nm deposited at a ratio of
An organic EL device was manufactured in the same manner as in Example 5. This device has a light emission luminance of 420 (cd /
m ² ) Orange light emission having a maximum light emission luminance of 11000 (cd / m ² ) and a light emission efficiency of 1.1 (lm / W) was obtained.

Example 19 As a light emitting layer, compound (16): bis (2-methyl-8)
An organic EL device was manufactured in the same manner as in Example 5, except that a 30-nm-thick thin film obtained by vapor-depositing -hydroxyquinolinato) (phenolate) gallium complex at a ratio of 1: 100 was provided. This device has an emission luminance of 6 at a DC voltage of 5 V.
00 (cd / m ² ), maximum emission luminance 12000 (cd / m ² )
m ² ), and orange luminescence with a luminous efficiency of 1.1 (lm / W) was obtained.

Example 20 The procedure of Example 5 was repeated except that a compound (16): tris (8-hydroxyquinolinato) aluminum complex was vapor-deposited at a ratio of 1: 100 to form a light-emitting layer having a thickness of 30 nm. An organic EL device was manufactured in the same manner. This device has a light emission luminance of 550 (cd / m ² ) at a DC voltage of 5 V, a maximum light emission luminance of 12100 (cd / m ² ), and a light emission efficiency of 1.3.
(Lm / W) red light emission was obtained.

Example 21 As a light emitting layer, 50% of compound (1): compound (16) was used.
An organic EL device was manufactured in the same manner as in Example 5, except that a thin film having a thickness of 30 nm deposited at a ratio of 50 was provided.
This device has an emission luminance of 450 (cd /
m ² ) Red light emission having a maximum light emission luminance of 8100 (cd / m ² ) and a light emission efficiency of 0.9 (lm / W) was obtained.

Example 22 As a light emitting layer, α-NPD: Compound (16) was used in the form of 100:
An organic EL device was manufactured in the same manner as in Example 15 except that a thin film having a thickness of 30 nm deposited at a ratio of 5 was provided. This device has an emission luminance of 540 (c) at a DC voltage of 5 V.
d / m ² ) Red light emission having a maximum light emission luminance of 12,500 (cd / m ² ) and a light emission efficiency of 1.0 (lm / W) was obtained.

Example 23 As a light emitting layer, compound (8): compound (16) was mixed with 50:
The same as Example 15 except that a thin film having a thickness of 30 nm deposited at a ratio of 50 was provided, and a tris (8-hydroxyquinolinato) aluminum complex was further vacuum-deposited to form an electron injection layer having a thickness of 30 nm. An organic EL device was produced by the method. This element has an emission luminance of 540 at a DC voltage of 5 V.
(Cd / m ² ), maximum emission luminance 16500 (cd / m ² ),
Orange light emission with a luminous efficiency of 1.5 (lm / W) was obtained.

The organic EL device shown in this embodiment has a maximum light emission luminance of 5000 (c
d / m ² ) or more, and high luminous efficiency was obtained in all cases. The organic EL device shown in this example was continuously emitted at 3 (mA / cm ² ).
Light emission stable for 000 hours or more could be observed.

The organic EL device of the present invention achieves improvement in luminous efficiency, luminous brightness and long life, and is used together with a luminescent material, a doping material, a hole injection material, an electron injection material, and a sensitizer. It does not limit the agent, resin, electrode material and the like, and the element manufacturing method.

[0119]

The organic EL device using the organic EL device material of the present invention as a light emitting material emits light from yellow to red, has higher luminous efficiency, higher luminance, and has a longer luminous life as compared with the prior art. The device was obtained.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of compound (1).

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H05B 33/14 H05B 33/14 B 33/22 33/22 D

Claims (10)

[Claims] 1. A substituent represented by the following general formula [1]:
A material for an organic electroluminescence device comprising a monocyclic compound or a condensed polycyclic compound having at least one compound. General formula [1] [Wherein, R ¹ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, A represents an oxygen atom or a methylene group represented by the general formula [2], Represents an oxygen atom or a sulfur atom. General formula [2] Wherein R ² and R ³ are each independently a hydrogen atom,
A substituent is represented by a group selected from a cyano group, a halogen atom, an alkylcarbonyl group, and an alkoxycarbonyl group, but is not simultaneously a hydrogen atom. Where R
² and R ³ may be combined with each other to be integrated. ] 2. A compound represented by the following general formula [3]:
The material for an organic electroluminescence device according to claim 1, comprising a monocyclic compound or a condensed polycyclic compound having at least one compound. General formula [3] [In the formula, R ⁴ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. ] 3. The organic electroluminescent device according to claim 1, wherein a part or all of a portion of the monocyclic compound or the condensed polycyclic compound other than the general formula [1] is electron-donating. material. 4. A part or all of a portion obtained by removing a general formula [1] from a monocyclic compound or a condensed polycyclic compound includes a partial structural formula represented by the following general formula [4] or general formula [5]. The material for an organic electroluminescence device according to claim 1, wherein: General formula [4] General formula [5] [Wherein, R ⁵ and R ⁶ represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, X represents a direct bond, a divalent substituted or unsubstituted alkyl group, A divalent substituted or unsubstituted aryl group,
Represents an oxygen atom, a nitrogen atom, a sulfur atom, a substituted or unsubstituted nitrogen atom, a carbonyl group, or a thiocarbonyl group. ] 5. An organic electroluminescence device comprising a light-emitting layer or a plurality of organic compound thin films including a light-emitting layer formed between a pair of electrodes, wherein one of the layers is an organic compound according to any one of claims 1 to 4. An organic electroluminescence device comprising a material for an electroluminescence device alone or as a mixture. 6. An organic electroluminescence device in which a light emitting layer or a plurality of organic compound thin films including the light emitting layer is formed between a pair of electrodes, wherein the light emitting layer is formed.
An organic electroluminescent device comprising any one of the materials for an organic electroluminescent device described above or as a mixture. 7. The organic electroluminescence device according to claim 5, wherein a hole injection layer is further formed between the anode and the light emitting layer. 8. The method according to claim 8, wherein the hole injection layer is an arylamine derivative,
The organic electroluminescent device according to claim 7, wherein the organic electroluminescent device is a layer containing at least one selected from the group consisting of a phthalocyanine compound and a triphenylene derivative. 9. The organic electroluminescence device according to claim 5, wherein an electron injection layer is further formed between the cathode and the light emitting layer. 10. The organic electroluminescence device according to claim 9, wherein the electron injection layer is a layer containing at least one selected from the group consisting of a metal complex compound and a nitrogen-containing aromatic ring compound.