JP2001288462A - Organic electroluminescent element material and organic electroluminescent element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element material which emits blue light, has a high luminance, and hence has a long luminescent life and provide an organic EL element prepared by using the same. SOLUTION: This material comprises a compound which has a maximum luminescence wavelength in the range of 400 nm-480 nm and is represented by formula I (wherein Ar1 is a functional group containing at least one partial structure represented by a specific formula and does not contain an aromatic fused-ring residue having three or more rings), e.g. formula 1 or 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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, and the electrons recombine with holes in the light emitting layer, and the energy level is changed to the conduction band. This is a phenomenon in which energy is emitted as light when returning to the valence band from.

[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.

In recent years, an organic EL device in which a thin film containing an organic compound having high fluorescence quantum efficiency which emits light at a low voltage of 10 V or less has been reported and attracted attention (Applied Physics Letters, vol. , 913, 1987).

In this method, a metal chelate complex is added to a light emitting layer,
High brightness green light emission is obtained by using an amine compound for the hole injecting layer.
00 (cd / m ² ) and the maximum luminous efficiency is 1.5 (lm / m ² ).
W) and has performance close to the practical range.

[0006]

However, the emission intensity of the blue organic EL device up to now has been improved by improving the structure, but it does not yet have a sufficient light emission luminance. In addition, there is a major problem that the stability upon repeated use is poor.

An object of the present invention is to provide a material for an organic EL device having a blue emission color, a high emission luminance, a long melting life due to a high melting point, and an organic EL device using the same.

[0008]

As a result of diligent studies conducted by the present inventors, an organic EL device using a material for an organic EL device represented by the general formula [1] for a light emitting layer emits blue light and has a light emission luminance. And high luminous efficiency and excellent luminous life. Further, the organic E represented by the general formula [1]
Since the light emitting material for L element contains only one amino group,
The ionization potential is higher as compared to a compound containing two amino groups. From this fact, it has been found that the band gap from the hole injection layer is reduced and a useful light emitting device having higher luminous efficiency is obtained.

The present invention relates to a material for an organic electroluminescence device comprising a compound represented by the following general formula [1] and having a maximum emission wavelength in a range of 400 nm to 480 nm. General formula [1]

[0010]

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[Wherein, Ar¹Are represented by the following general formulas [2] to
A government containing at least one of the partial structural formulas represented by [5].
Aromatic condensed ring which is a functional group and is composed of three or more rings
Does not contain residues. Ar^FourAnd Ar^FiveAre independent
And only one monovalent ring which may have a substituent
Aromatic ring residue or aromatic condensate consisting only of two rings
A fused ring residue or a combination thereof, and three or more
Does not include a fused aromatic ring residue consisting of Ar^TwoAnd
And Ar^ThreeIs independently 2 which may have a substituent
Aromatic ring residue consisting of only one ring or two valences
Aromatic Fused Ring Residues Consisting of Only Rings or Their Bonds
, And an aromatic fused ring residue consisting of three or more rings
Contains no groups. X and Y are each independently
, -O-, -S-,> C = O,> SO _Two, -Si
(R¹) R^Two-, -N (R¹)-, -PR¹-, -P (=
O) R¹-, A substituted or unsubstituted alkylene group,-
(CH_Two) N-O- (CH_Two) M-, or substitution or
Represents an unsubstituted aliphatic ring residue;¹And R^TwoIs it
Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl
And n represents an aromatic ring residue, and n and m are each 0 to
Represents an integer of 20, but does not satisfy n + m = 0. General formula [2]

[0012]

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General formula [3]

[0014]

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Wherein A is an oxygen atom, a sulfur atom, -C
(R¹) (R^Two)-Or -N (R ¹)-, B
Is a nitrogen atom or -C (R¹) =, R¹You
And R^TwoAre each independently a hydrogen atom, a substituted or
Represents an unsubstituted alkyl group or aromatic ring residue. General formula [4]

[0016]

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Wherein A is an oxygen atom, a sulfur atom, -C
(R¹) (R^Two)-Or -N (R ¹)-, B
Is a nitrogen atom or -C (R¹) =, R¹You
And R^TwoAre each independently a hydrogen atom, a substituted or
Represents an unsubstituted alkyl group or aromatic ring residue. General formula [5]

[0018]

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Wherein C and D are each independently:
Direct bond, oxygen atom, sulfur atom, -C (R ¹ ) (R ² )
— Or —N (R ¹ ) —, wherein R ¹ and R ² are
Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or an aromatic ring residue. Further, the present invention provides an organic electroluminescence element in which a light-emitting layer or a plurality of organic compound thin films including a light-emitting layer is formed between a pair of electrodes, wherein any one of the layers is formed of the material for an organic electroluminescence element. The present invention relates to an organic electroluminescence device characterized by being contained alone or as a mixture.

The present invention also relates to an organic electroluminescent 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 electroluminescent device material alone. Alternatively, the present invention relates to an organic electroluminescence device characterized in that it is contained as a mixture.

The present invention further relates to the above-mentioned organic electroluminescent device, wherein a hole injection layer is formed between the anode and the light emitting layer.

Further, in the present invention, the hole injection layer is a layer containing at least one member selected from the group consisting of an arylamine derivative, a phthalocyanine compound, and a triphenylene derivative. About.

Further, the present invention further relates to the above organic electroluminescent device, wherein an electron injection layer is formed between the cathode and the light emitting layer.

Further, the present invention relates to the above organic electroluminescent device, wherein the electron injection layer is a layer containing a metal complex compound or a nitrogen-containing aromatic ring compound.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The general formula [1] used in the present invention
Is 400 nm to emit blue light.
It is necessary to have a maximum emission wavelength in the range of ４480 nm. Therefore, Ar ¹ is represented by the general formulas [2] to [5]
Is a functional group containing at least one of the partial structural formulas, wherein Ar ^{2 to} Ar ⁵ may be substituted,
It must be an aromatic residue consisting of only one ring, an aromatic fused ring residue consisting of only two rings, or a combination thereof.

The aromatic ring residue referred to in the present invention is a functional group having an aromatic ring as a skeleton, and is an aryl group or a heterocyclic group, and is classified into a monocyclic group and a polycyclic group. You.

The term "aromatic condensed ring residue" as used herein means a ring residue in which all the constituent aromatic rings are peri-condensed or cata-condensed with any other aromatic ring.

The aromatic residue consisting of only one ring includes phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-ethylphenyl, 3,5-dichlorophenyl and the like. An aryl group of
And heterocyclic groups such as furanyl group, thiophenyl group, pyrrole group, pyranyl group, thiopyranyl group, pyridinyl group, thiazolyl group, imidazole group, pyrimidinyl group, pyridinyl group and triazinyl group.

The aromatic condensed ring residue consisting of only two rings includes an aryl group such as a naphthyl group and a 5-methylnaphthyl group, and a heterocyclic group such as an indolinyl group, a quinolyl group and a purinyl group.

Further, an aromatic residue consisting of only one ring, such as a biphenyl group or a functional group represented by the general formula [4], forms a conjugate without forming a condensed ring such as peri-condensation or cata-condensation. You can make it.

An aromatic residue consisting of only two rings or an aromatic residue consisting of only one ring and an aromatic condensed ring residue consisting of only two rings are formed by peri-condensation or cata-condensation. Such a conjugate may be formed without forming a condensed ring.

However, when at least one of Ar ^{1 to} Ar ⁵ contains an aromatic condensed ring residue having three or more rings, the maximum emission wavelength of the compound represented by the general formula [1] is as follows:
It becomes larger than 480 nm and can no longer be said to be blue light emission.

In the present invention, the aromatic condensed ring residue having three or more rings includes anthracene, phenanthrene, perylene and the like. For example, phenylnaphthalene is a phenyl group which is neither peri-condensed nor cata-condensed. It is not an aromatic fused ring residue consisting of three or more rings in the present invention.

Ar ^{1 to} Ar ⁵ may be substituted with a halogen atom, a cyano group, an alkyl group, an alkoxy group, an alkylthio group, an aromatic ring group or a cycloalkyl group within a range that does not affect the maximum emission wavelength. Good.

When all of Ar ^{1 to} Ar ⁵ consist only of a benzene ring, the maximum emission wavelength becomes smaller than 400 nm, and blue light is no longer emitted.

The compound represented by the general formula [1] is
In order to have a maximum emission wavelength in the range of from 480 to 480 nm, at least one of Ar ^{1 to} Ar ⁵ must have the general formula [2] to
It preferably has at least one of the ring skeletons represented by [5]. In particular, it is preferable that Ar ¹ has at least one of the ring skeletons represented by the general formulas [2] to [5].

X and Y in the general formula [1] are each independently
First, a direct bond, -O-, -S-,> C = O,> S
O_Two, -Si (R¹) R^Two-, -N (R¹)-, -PR
¹-, -P (= O) R¹-, Substituted or unsubstituted alkyl
Len group,-(CH_Two) N-O- (CH _Two) M-, or
Represents a substituted or unsubstituted aliphatic ring residue.

R ¹ and R ² in the present invention each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group,
Represents an aromatic ring residue. N and m are each 0
Represents an integer of ２０20, but does not satisfy n + m = 0.

Examples of the substituted or unsubstituted alkylene group include an alkylene group having 1 to 20 carbon atoms such as a methylene group, an ethylene group and a propylene group, a 2-phenylisopropylene group, a dichloromethylene group, a difluoromethylene group and a benzylene group. , Α-phenoxybenzylene group, α,
Substituted alkylene groups such as an α-dimethylbenzylene group, an α, α-methylphenylbenzylene group, a diphenylmethylene group, and an α-benzyloxybenzylene group.

Examples of the substituted or unsubstituted aliphatic ring residue include those having 5 to 5 carbon atoms such as a cyclopentyl ring, a cyclohexyl ring, a 4-methylcyclohexyl ring and a cycloheptyl ring.
The divalent residue of the aliphatic ring of 7 is raised.

Examples of the substituted or unsubstituted alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group and a
Unsubstituted linear or branched alkyl groups having 1 to 20 carbon atoms such as a c-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a stearyl group, and 2-phenylisopropyl Group, trichloromethyl group, trifluoromethyl group, benzyl group, α-phenoxybenzyl group, α, α-dimethylbenzyl group, α, α-methylphenylbenzyl group, α, α-ditrifluoromethylbenzyl group, triphenylmethyl And substituted alkyl groups having 1 to 20 carbon atoms such as α-benzyloxybenzyl group.

These are each independently a hydrogen atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group. Group or a substituted or unsubstituted arylthio group.

As specific examples of the substituent which may be substituted,
Halogen atoms include fluorine, chlorine, bromine and iodine.

As the substituted or unsubstituted alkyl group, the same as the above-mentioned alkyl groups can be exemplified.

The substituted or unsubstituted alkoxyl group includes methoxy, ethoxy, propoxy, n-butoxy, t-butoxy, n-octyloxy, t-
And-an alkoxyl group having 1 to 20 carbon atoms such as an octyloxy group, a 1,1,1-tetrafluoroethoxy group, a phenoxy group, a benzyloxy group and an octylphenoxy group.

As the substituted or unsubstituted aryl group, the same as the above-mentioned aryl group can be exemplified.

The substituted or unsubstituted aryloxy group includes phenoxy, 4-nitrophenoxy, te
There are an rt-butylphenoxy group, a 3-fluorophenoxy group, a pentafluorophenyl group, a trifluoromethylphenoxy group and the like.

The substituted or unsubstituted arylthio group includes a phenylthio group, a 4-methylphenylthio group, te
Examples include an rt-butylphenylthio group, a 3-fluorophenylthio group, a pentafluorophenylthio group, and a 3-trifluoromethylphenylthio group.

The compound represented by the general formula [1] can be synthesized by the following method. General formulas [2] to [5] in which one hydrogen atom is halogenated in an inert solvent.
Is reacted with an aromatic diamine compound with a catalyst such as copper at 200 ° C. for a long time to obtain a compound represented by the general formula [1]:
Is synthesized. As another synthesis method, there is a method in which a monoaminated compound represented by the general formulas [2] to [5] is reacted with an aryl halide derivative in an inert solvent. Examples of the catalyst include copper powder, cuprous chloride, tin, stannous chloride and the like.
Solvents include N, N-dimethylformamide, dimethylsulfoxide, nitrobenzene and the like.

The compound represented by the general formula [1] is converted to an organic E
When used for the light emitting material of the L element, each element showed high luminous efficiency in the blue light emitting region. Furthermore, the material of the present invention often has a melting point of 200 ° C. or higher,
This is extremely advantageous when producing a device having a high maximum emission luminance and a long life.

Representative examples of the compound represented by the general formula [1] are specifically shown in Table 1, but are not limited thereto.

[0052]

[Table 1]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

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 injection property, a hole transport property and an electron injection property, and an electron transport property.
It can be used in a light emitting layer as a light emitting material.

In the light emitting layer, if necessary, further known light emitting materials, doping materials, hole injection materials and electron injection materials can be used in addition to the compound of the present invention. 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,
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 proportion of the compound of the present invention and the above compounds which can be used together in the light emitting layer in the light emitting layer may be any of the main components. 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, tolyldiphenylamine, 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 electron injecting effect on 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 injecting 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 element, 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 substance 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 deposition, 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 light-emitting device.
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.

[0084]

The present invention will be described in more detail with reference to the following examples. Synthesis method of compound (1) In 50 ml of 1,3-dimethyl-2-imidazolidinone, 2.14 g of 2-bromo-benzothiazole, 1,4
3.70 g of dibiphenylamine, 6 g of potassium carbonate and 0.2 g of copper powder were added, and the mixture was heated and stirred at 200 ° C. for 50 hours. Thereafter, the mixture was diluted with 500 ml of water, extracted and concentrated with ethyl acetate, and purified by column chromatography using silica gel to obtain 3 g of a powder having blue fluorescence. Analysis by FD-MS such as molecular weight analysis and NMR spectrum confirmed that it was Compound (1). Synthesis method of compound (8) In 50 ml of nitrobenzene, 2.07 g of 2-bromo-naphthalene, 4.00 g of 1,4-dibiphenylamine,
And 6 g of potassium carbonate and 0.2 g of copper powder.
The mixture was heated and stirred at 0 ° C. for 30 hours. Thereafter, the mixture was diluted with 500 parts of water and extracted with chloroform.
The chloroform layer was concentrated, purified by column chromatography using silica gel, and reprecipitated with n-hexane to obtain 3.5 g of a powder having blue fluorescence. It was confirmed to be Compound (8) by analysis of molecular weight analysis, NMR spectrum and the like by FD-MS. The infrared absorption spectrum (KBr tablet method) of this compound is shown in FIG.
Shown in The fluorescence spectrum (chloroform solution)
Is shown in FIG.

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

Example 1 Compound (1) of 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 20.
(Cd / m ² ), blue light emission with a maximum emission luminance of 450 (cd / m ² ) and luminous efficiency of 0.10 (lm / W) was obtained.

Example 2 N, N ′-(3) was placed on a cleaned glass plate with ITO electrodes.
-Methylphenyl) -N, N'-diphenyl-1,1 '
-Biphenyl-4,4'-diamine (TPD) was vacuum-deposited to obtain a 20-nm-thick hole injection layer. Next, compound (2) was deposited to form a light emitting layer having a thickness of 40 nm, and then tris (8-hydroxyquinolinato) aluminum complex (Alq3) was deposited to obtain an electron injection layer having a thickness of 30 nm. 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 an emission luminance of 60 (cd / m ² ) at a DC voltage of 5 V, a maximum emission luminance of 5000 (cd / m ² ), and an emission efficiency of 0.5 (l).
m / W).

Example 3 A compound (7) 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 100 at a DC voltage of 5 V.
(Cd / m ² ), maximum emission luminance 5500 (cd / m ² )
m ² ) and blue luminescence with a luminous efficiency of 0.60 (lm / W) was obtained.

Example 4 Compound (11) 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 an emission luminance of 150 (cd / m ² ) at a DC voltage of 5 V and a maximum emission luminance of 10,000.
(Cd / m ² ) and blue luminescence with a luminous efficiency of 1.1 (lm / W) were 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 2 shows the light emission characteristics of this device. The emission luminance here is the luminance when a DC voltage of 5 V is applied. The organic EL elements of this example all had a maximum luminance of 5000 (cd / m
² ) It has high luminance characteristics as described above, and it was possible to obtain luminescent colors up to blue.

[0091]

[Table 2]

Example 15 4,4 ′, 4 ″ was placed on a washed glass plate with an ITO electrode.
-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 luminance of 210 (cd / m ² ) at a DC voltage of 5 V, a maximum luminance of 9000 (cd / m ² ), and a luminous efficiency of 1.2 (lm).
/ W) blue light emission was obtained.

Example 16 Example 3 was repeated except that a hole injection layer of copper phthalocyanine having a thickness of 5 nm was provided between the ITO electrode and the compound (18).
An organic EL device was produced in the same manner as in the above. This element
DC voltage emission luminance at ^{5V 60 (cd / m 2)} , the maximum emission luminance 12000 (cd / m ^2), luminous efficiency 1.1 (lm
/ W) blue light emission was obtained.

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 50 at a DC voltage of 5 V.
(Cd / m ² ), maximum emission luminance 11000 (cd / m ² )
m ² ) and blue 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 an emission luminance of 150 (cd /
m ² ) Blue light emission having a maximum light emission luminance of 12000 (cd / m ² ) and a light emission efficiency of 1.1 (lm / W) was obtained.

Example 19 As a light emitting layer, compound (19): 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 2 at a DC voltage of 5 V.
90 (cd / m ² ), maximum emission luminance 12000 (cd / m ² )
m ² ) and blue luminescence with a luminous efficiency of 1.1 (lm / W) was obtained.

Example 20 Compound (24): bis (2-methyl-8) was used as the light emitting layer.
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 1 at a DC voltage of 5 V.
50 (cd / m ² ), maximum light emission luminance 15000 (cd / m ² )
m ² ) and blue luminescence with a luminous efficiency of 1.4 (lm / W) was obtained.

Comparative Example 1 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) was vacuum-deposited on a washed glass plate with an ITO electrode to a thickness of 30 nm. Was formed. Next, as a light emitting material, the compound (3
1) was vacuum-deposited 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. This device has an emission luminance of 10 at a DC voltage of 5 V.
0 (cd / m ² ), maximum emission luminance 4200 (cd / m ² )
m ² ) and blue luminescence with a luminous efficiency of 0.4 (lm / W) were obtained, but the luminescent surface was spotty and the luminescent life was several hours. Compound [31]

[0099]

Embedded image

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. When the organic EL device shown in this example was continuously emitted at 3 (mA / cm ² ),
Light emission stable for 1000 hours or more could be observed.

The organic EL device of the present invention achieves an improvement in luminous efficiency and luminance and a 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.

[0102]

The organic EL device using the organic EL device material of the present invention as a light-emitting material emits blue light, has higher luminous efficiency and higher brightness than conventional ones, and has a long glass transition point or melting point. An organic EL device having a light emission lifetime was obtained.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of compound (8).

FIG. 2 is a fluorescence spectrum diagram of compound (8).

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 11/06 660 C09K 11/06 660 H05B 33/14 H05B 33/14 B 33/22 33/22 C

Claims (7)

[Claims] 1. A compound represented by the following general formula [1] and having a maximum
Compounds whose light wavelength is in the range of 400 nm to 480 nm
Material for organic electroluminescence devices consisting of a product. General formula [1][Wherein, Ar¹Is represented by the following general formulas [2] to [5].
A functional group containing at least one of the partial structural formulas
Does not include an aromatic fused ring residue consisting of three or more rings.
No. Ar^FourAnd Ar^FiveEach independently have a substituent
Monovalent aromatic ring residue consisting of only one ring
Or an aromatic fused ring residue consisting of only two rings, or
A combination of these and three or more rings
Does not contain aromatic fused ring residues. Ar^TwoAnd Ar^ThreeIs it
Each independently may have a substituent, divalent one ring
Only aromatic ring residues or two rings
An aromatic fused ring residue or a conjugate thereof, and
Does not include aromatic fused ring residues consisting of three or more rings. X
And Y are each independently a direct bond, -O-, -S
−,> C = O,> SO _Two, -Si (R¹) R^Two-, -N
(R¹)-, -PR¹-, -P (= O) R¹−, If substitution
Or an unsubstituted alkylene group,-(CH_Two) NO- (C
H_TwoM) or a substituted or unsubstituted aliphatic ring residue
R represents a group¹And R^TwoAre each independently a hydrogen source
Substituents, substituted or unsubstituted alkyl groups and aromatic ring residues
And n and m each represent an integer of 0 to 20
However, there is no case where n + m = 0. General formula [2]General formula [3][Wherein A is an oxygen atom, a sulfur atom, -C (R¹)
(R^Two)-Or -N (R ¹)-, Wherein B is nitrogen
Atom or -C (R¹) =, R¹And R^Two
Are each independently a hydrogen atom, a substituted or unsubstituted
Represents an alkyl group or an aromatic ring residue. General formula [4][Wherein A is an oxygen atom, a sulfur atom, -C (R¹)
(R^Two)-Or -N (R ¹)-, Wherein B is nitrogen
Atom or -C (R¹) =, R¹And R^Two
Are each independently a hydrogen atom, a substituted or unsubstituted
Represents an alkyl group or an aromatic ring residue. General formula [5][Wherein, C and D each independently represent a direct bond, an acid
Element atom, sulfur atom, -C (R¹) (R^Two)-Or-
N (R¹)-, R¹And R^TwoAre independent
Has a hydrogen atom, a substituted or unsubstituted alkyl group,
Represents a group ring residue. ] 2. An organic electroluminescent 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 any one of the layers is used for the organic electroluminescent device according to claim 1. An organic electroluminescent device comprising a material alone or as a mixture. 3. 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 comprises the material for an organic electroluminescence device according to claim 1 alone. Alternatively, an organic electroluminescence device, which is contained as a mixture. 4. The organic electroluminescence device according to claim 2, further comprising a hole injection layer formed between the anode and the light emitting layer. 5. The method according to claim 1, wherein the hole injection layer is an arylamine derivative,
The organic electroluminescence device according to claim 4, wherein the organic electroluminescence device is a layer containing at least one selected from the group consisting of a phthalocyanine compound and a triphenylene derivative. 6. The organic electroluminescence device according to claim 2, wherein an electron injection layer is further formed between the cathode and the light emitting layer. 7. The organic electroluminescent device according to claim 7, wherein the electron injection layer is a layer containing a metal complex compound or a nitrogen-containing aromatic ring compound.