JP2001207167A - Light-emission material for organic electro-luminescent element and organic electro-luminescent element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emission material for organic EL elements that can emit the light of from the bluish green to the red color with high emission brightness and has the long emission lifetime because the material has a high melting point. SOLUTION: The objective material for organic electroluminescent(EL) element comprises a compound represented by the 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 and a display, and a light emitting device with 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, 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 organic EL devices up to now have improved light emission intensity due to the improved structure, but do not yet have sufficient light emission luminance. In addition, there is a major problem that the stability upon repeated use is poor. The inventor of the present invention has proposed in Japanese Patent Application Laid-Open No. 9-157463 that a specific amine compound having a diarylamino group introduced at the 9-position of the anthracene ring is used as the organic EL light-emitting material. Because of its low crystallinity and high crystallinity, it is greatly deteriorated by short-time light emission. Also, the emission color is blue-green to green, and yellow to red emission cannot be expected.
For the above reasons, emission colors from blue to red can be obtained, high emission brightness, high luminous efficiency, and excellent light emitting ability and durability for the development of organic EL elements having a long life. Light emitting materials are desired.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a luminescent material for an organic EL device which has a luminescent color from blue green to red, has a high luminous luminance, and has a long luminous life due to a high melting point, and the use of the luminescent material. To provide an organic EL device.

[0008]

As a result of intensive studies by the present inventors, an organic EL device using a light-emitting material for an organic EL device represented by the general formula [1] or [2] for a light-emitting layer is as follows: It has been found that it emits blue to red light, has high light emission luminance and light emission efficiency, and has an excellent light emission lifetime. Further, the organic E represented by the general formula [1] or the general formula [2]
Since the light emitting material for L element contains only one amino group,
The ionization potential is lower 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 electroluminescent device comprising a compound represented by the following general formula [1]. General formula [1]

[0010]

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[In the formula, Ar ¹ and Ar ² each independently represent a substituted or unsubstituted aryl group or a substituted or unsubstituted aromatic heterocyclic group. Where Ar ¹
And Ar ² may be combined with each other to be integrated. R ¹
At least one of R ⁹ to R ⁹ is 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, Or an unsubstituted aromatic heterocyclic group or a substituted or unsubstituted aromatic heterocyclic oxy group. R ^{1 to} R ⁹ may be bonded together by adjacent substituents to be integrated. ]Also,
The present invention relates to a material for an organic electroluminescence device represented by the general formula [2]. General formula [2]

[0012]

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[In the formula, Ar ³ and Ar ⁴ each independently represent a divalent substituted or unsubstituted arylene group or a substituted or unsubstituted aromatic heterocyclic group. However, Ar ³ and Ar ⁴ may be combined with each other and integrated. Ar ⁵ and Ar ⁶ each independently represent a substituted or substituted aryl group or a substituted or unsubstituted aromatic heterocyclic group. X ¹ and X ² are each independently a direct bond, O, S, C = O , SO 2, (CH 2) x-
O- (CH ₂₎ y, represents a divalent aliphatic ring residue of a substituted or unsubstituted alkylene group or a substituted or unsubstituted,. Here, x and y each represent a positive integer of 0 to 20; however, x + y = 0 does not occur. R ^{1 to} R ⁹
At least one of which is 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, a substituted or unsubstituted Or a substituted or unsubstituted aromatic heterocyclic oxy group. R ¹ and R ⁹ may be bonded together by adjacent substituents to be integrated. Further, in the present invention, R ⁵ represents a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aryloxy group The material for an organic electroluminescence device described above,

Further, the present invention relates to the material for an organic electroluminescent device, wherein R ^{1 to} R ⁹ are bonded together by adjacent substituents to be integrated.

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.

Further, the present invention provides the above organic electroluminescence 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.

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

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The aryl group and the arylene group referred to in the present invention are aromatic hydrocarbon groups and aromatic groups not containing a heterocyclic ring, and are monocyclic and fused with two or more rings. Some are polycyclic. Examples of the monocyclic ring include a benzene ring, and examples of the condensed polycyclic ring include a naphthalene ring, an anthracene ring, a phenanthrene ring, a fluorene ring, a pyrene ring, a perylene ring, and a triphenylene ring. These may be substituted by substituents represented by R ^{1 to} R ⁹ described below.

The aromatic heterocyclic ring referred to in the present invention includes pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring, indoline ring, quinoline ring, acridine ring, carbazole ring, furan ring, thiophene ring,
2-3 carbon atoms such as an oxazole ring, an oxadiazole ring, a benzoxazole ring, a thiazole ring, a thiadiazole ring, a benzothiazole ring, a triazole ring, a benzotriazole ring, an imidazole ring, and a benzimidazole ring.
There are 0 substituted or unsubstituted aromatic heterocycles. These may be substituted by substituents represented by R ^{1 to} R ⁹ described below.

The aromatic heterocyclic oxy group referred to in the present invention is a substituent in which the above-mentioned aromatic heterocyclic residue is bonded to an oxygen atom.

In the present invention, Ar ^{1 and} Ar ² of the compound represented by the general formula [1] and Ar ^{5 and} Ar ⁶ of the compound represented by the general formula [2] each independently represent a substituted or unsubstituted aryl. Represents a group or a substituted or unsubstituted aromatic heterocyclic group.

However, Ar ¹ and Ar ² may be bonded to each other to form a heterocyclic ring. As the heterocyclic ring, a carbazole ring, a pyrrolidine ring, a dioxolane ring,
There are a pyrazolidine ring, a piperidine ring, a dioxane ring, a morpholine ring, a piperazine ring, a trithiane ring and the like, and the above aromatic heterocycle.

Ar ³ and Ar ^{4 represented} by the general formula [2]
Each independently represents a divalent substituted or unsubstituted arylene group or a substituted or unsubstituted aromatic heterocyclic group.

However, Ar ³ and Ar ⁴ may be combined with each other to form an integral or heterocyclic ring. Specific examples of the heterocyclic ring include A of the compound represented by the general formula [1].
The same heterocyclic rings as those exemplified in the description of r ¹ and Ar ² can be exemplified.

Further, the substituent R represented by the general formula [1]
^{1 to} R ⁹ are each independently a hydrogen atom, a halogen atom,
Represents a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aryloxy group.

As specific examples, halogen atoms include fluorine, chlorine, bromine and iodine.

Examples of the substituted or unsubstituted alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group and a
c-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, stearyl group, 2-
Phenylisopropyl, trichloromethyl, trifluoromethyl, benzyl, α-phenoxybenzyl, α, α-dimethylbenzyl, α, α-methylphenylbenzyl, α, α-ditrifluoromethylbenzyl, There is a substituent of an alkyl group having 1 to 30 carbon atoms such as a phenylmethyl group and an α-benzyloxybenzyl group.

The substituted or unsubstituted alkoxyl groups include 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.

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.

R ^{1 to} R ⁹ may be bonded to each other by adjacent substituents to form a new ring. Specific examples thereof include a naphthacene ring such as compound (10) and a compound (23). Such a six-membered aryl ring such as a pentacene ring can be exemplified.

X ¹ and X ^{2 in} the general formula [2] are each independently a direct bond, O, S, C ＝ O, SO ₂ , (CH ₂ )
It represents the _{x-O- (CH 2) y} , a substituted or unsubstituted alkylene, substituted or unsubstituted aliphatic ring residue. Here, x and y each represent a positive integer of 0 to 20; however, x + y = 0 does not occur.

As the substituted or unsubstituted alkylene group, an alkylene group having 1 to 20 carbon atoms or a substituted product thereof, and as a substituted or unsubstituted divalent aliphatic ring residue, a cyclopentyl ring, a cyclohexyl ring, a 4-methyl Examples thereof include divalent residues of an aliphatic ring having 5 to 7 carbon atoms such as a cyclohexyl ring and a cycloheptyl ring.

X¹And X^TwoSubstituted alkylene group or substituted
Examples of the substituent of the aliphatic ring residue include R ¹~ R⁹Replacement indicated by
There are groups. X¹And X^TwoPreferred as a substituted alkylene group
New ones are 2,2-propylene group, dichloromethylene
Group, difluoromethylene group, phenoxymethylene group,
Tylphenylmethylene group, diphenylmethylene group, ben
And a ziroxymethylene group.

In the case of direct bonding, a biphenyl group as in the compound (3), a terphenyl group as in the compound (9) and the like can be exemplified.

The material for an organic electroluminescent device of the present invention may be used in order to increase the glass transition point or melting point of the anthracene ring, by using a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, Alternatively, an unsubstituted aryl group or a substituted or unsubstituted aryloxy group is substituted.

Among these compounds, compounds in which R ^{1 to} R ⁹ have an aryl group or an aryloxy group having an aromatic ring, or R ^{1 to} R ⁹ form a ring with adjacent substituents The compound having a higher glass transition point and melting point than the compound having no such a substituent and having Joule generated in an organic layer, an organic layer, or between an organic layer and a metal electrode during electroluminescence. Since the resistance to heat (heat resistance) is improved, when used as a light emitting material of an organic EL element, it exhibits high light emission luminance and is advantageous when light is emitted for a long time.

From the viewpoint of synthesis, it is particularly preferred that R ⁵ of R ^{1 to} R ⁹ is substituted.

As a typical example, compound (2) shown in Table 1
Has a melting point of 180 ° C., whereas the melting point of compound (37) is as low as 125 ° C. That is, R in the general formula [1]
^{When 5} is a phenyl group, a melting point rise of 50 ° C. or more is observed.

The compounds of the present invention are not limited to these substituents.

The compound represented by the general formula [1] or the general formula [2] can be synthesized by the following method. A halogenated anthracene derivative and an aromatic diamine compound are reacted with each other with a catalyst such as copper at 200 ° C. for a long time in an inert solvent to synthesize an aromatic amine compound represented by the general formula [1]. As another synthesis method, there is a method of reacting an aminated anthracene derivative and 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.

When the compound represented by the general formula [1] or [2] is used as a light emitting material of an organic EL device,
Each device showed high luminous efficiency in a wide light emitting region from blue green to red. Further, the material of the present invention comprises 20
Many of them have a melting point of 0 ° C. or higher, and have a high maximum emission luminance, which is extremely advantageous in producing a long-life element.

Representative examples of the compound represented by the general formula [1] or [2] are specifically shown in Table 1, but are not limited thereto.

[0046]

[Table 1]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

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.

The organic EL device is a device in which one or more organic thin films are 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 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 injection materials that can be used in the organic EL device of the present invention, more effective hole injection 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 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, it is desirable that at least one of the devices is 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.

Each layer of the organic EL device according to the present invention may 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, the characteristics of the organic EL device such as the luminous efficiency and the maximum emission luminance could be improved. 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.

[0078]

The present invention will be described in more detail with reference to the following examples. Synthesis method of compound (2) 9-bromo-10-phenylanthracene 6.6 in 50 ml of 1,3-dimethyl-2-imidazolidinone
g, p, p'-ditolylamine, 5.9 g, potassium carbonate, 12 g, and copper powder, 0.5 g, were heated and stirred at 200 ° C. for 50 hours. Thereafter, the mixture was diluted with 500 ml of water, extracted with ethyl acetate and concentrated, and purified by column chromatography using silica gel to obtain 6 g of a powder having yellow fluorescence. Molecular weight analysis by FD-MS, NM
Analysis by R spectrum or the like confirmed that it was Compound (2). The infrared absorption spectrum of this compound (KBr
The tablet method is shown in FIG. Synthesis method of compound (7) In 50 ml of nitrobenzene, 9-bromo-10-(-
7.8 g of 2-benzothiazolyl) anthracene,
12.5 g of 4′-di (2-phenylisopropyl) diphenylamine, 12 g of potassium carbonate, and 0.5 g of copper powder were added, and the mixture was heated and stirred at 200 ° C. for 30 hours.
Thereafter, the mixture was diluted with 500 parts of water and extracted with chloroform. This chloroform layer is concentrated,
Purification was performed by column chromatography using silica gel, and reprecipitation was performed with n-hexane to obtain 8 g of a yellow fluorescent powder. Molecular weight analysis by FD-MS, NM
Analysis by R spectrum or the like confirmed that it was Compound (7).

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 (2) 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 ), green light emission with a maximum emission luminance of 650 (cd / m ² ) and a luminous efficiency of 0.30 (lm / W) were obtained.

Example 2 On a cleaned glass plate with ITO electrodes, 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, compound (3) 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 a light emission luminance of 120 (cd / m ² ) at a DC voltage of 5 V, a maximum light emission luminance of 15000 (cd / m ² ), and a light emission efficiency of 1.2.
Green light emission of (lm / W) was obtained.

Example 3 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 spin coating. 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 )
m ² ) and green 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 250 (cd / m ² ) at a DC voltage of 5 V and a maximum emission luminance of 10200.
(Cd / m ² ) and green 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. All of the organic EL elements of this example had a maximum luminance of 10,000 (cd /
m ² ) or more, and emission colors of blue-green to red could be obtained.

[0085]

[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, the compound (5) was 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 was 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 19000 (cd / m ² ), and a light emission efficiency of 1.7 (l).
m / W).

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 (15).
An organic EL device was produced in the same manner as in the above. This element
At a DC voltage of 5 V, the light emission luminance is 60 (cd / m ² ), the maximum light emission luminance is 12000 (cd / m ² ), and the light emission efficiency is 1.6 (lm).
/ W) 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 12,000 (cd / m ² )
m ² ) and green luminescence with a luminous efficiency of 1.3 (lm / W) was obtained.

Example 18 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 250 (cd /
m ² ) Green light emission having a maximum light emission luminance of 13000 (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 2 at a DC voltage of 5 V.
90 (cd / m ² ), maximum emission luminance 12000 (cd / m ² )
m ² ), and yellow luminescence with a luminous efficiency of 1.1 (lm / W) was obtained.

Example 20 Compound (22): 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 2 at a DC voltage of 5 V.
50 (cd / m ² ), maximum light emission luminance 15000 (cd / m ² )
m ² ), and orange luminescence with a luminous efficiency of 1.3 (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
7) 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 light emission luminance 3200 (cd / m ² )
m ² ) and green light emission with a light emission efficiency of 0.2 (lm / W) was obtained, but the light emission surface was spotty and the light emission life was several hours. Compound [37]

[0093]

Embedded image

As is apparent from a comparison between Comparative Example 1 and Example 5, remarkable improvements in characteristics such as maximum emission luminance were observed when R ⁵ had a substituent.

The organic EL device shown in this embodiment has a maximum light emission luminance of 10,000
Light emission of (cd / m ² ) or more was obtained, 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 ), stable emission was observed for 1000 hours or more.

The organic EL device of the present invention achieves an improvement in luminous efficiency, luminous 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.

[0097]

The organic EL device using the organic EL device material of the present invention as a light emitting material emits light from blue-green to red, has higher luminous efficiency and higher brightness than the conventional one, and has a high glass transition point or melting point. As a result, an organic EL device having a long emission life was obtained.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of compound (2).

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C09K 11/06 690 C09K 11/06 690 H05B 33/14 H05B 33/14 B

Claims (10)

[Claims] 1. A material for an organic electroluminescence device comprising a compound represented by the following general formula [1]. General formula [1] [In the formula, Ar ¹ and Ar ² each independently represent a substituted or unsubstituted aryl group or a substituted or unsubstituted aromatic heterocyclic group. However, Ar ¹ and Ar ² are
They may be combined with each other to be integrated. At least one of R ^{1 to} R ⁹ is 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 Represents a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted aromatic heterocyclic oxy group. R ^{1 to} R ⁹ may be bonded together by adjacent substituents to be integrated. ] 2. A material for an organic electroluminescence device represented by the following general formula [2]. General formula [2] [In the formula, Ar ³ and Ar ⁴ each independently represent a divalent substituted or unsubstituted arylene group or a divalent substituted or unsubstituted aromatic heterocyclic group. However, A
r ³ and Ar ⁴ may be combined with each other to be integrated.
Ar ⁵ and Ar ⁶ each independently represent a substituted or aryl group, or a substituted or unsubstituted aromatic heterocyclic group. X ¹ and X ² are each independently a direct bond, O, S, C ＝ O, SO ₂ , (CH ₂ ) x-O- (CH
₂ ) y represents a substituted or unsubstituted alkylene group or a substituted or unsubstituted divalent aliphatic ring residue. Here, x and y each represent a positive integer of 0 to 20; however, x + y = 0 does not occur. At least one of R ^{1 to} R ⁹ is 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 Represents a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted aromatic heterocyclic oxy group. R ^{1 to} R ⁹ may be bonded together by adjacent substituents to be integrated. ] 3. R ⁵ is a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aryloxy group. The material for an organic electroluminescence device according to claim 1 or 2, wherein: 4. The material for an organic electroluminescence device according to claim 1, wherein R ^{1 to} R ⁹ are bonded together by adjacent substituents. 5. 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 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 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 an organic electroluminescence device according to claim 1. An organic electroluminescent device comprising a material for use alone 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 electroluminescence device according to claim 7, 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. 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 electroluminescent device according to claim 9, wherein the electron injection layer is a layer containing a metal complex compound or a nitrogen-containing aromatic ring compound.