JPH1053759A - Organic electroluminescent element material and organic electroluminescent element prepared therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel org. electroluminescent element material which causes electrons to be injected from a cathode ray tube efficiently and is excellent in luminescent characteristics and to obtain an org. electroluminescent element which exhibits high luminance and luminous efficiency and hardly undergoes degradation by using the same. SOLUTION: This material is represented by formula I [wherein R<1> to R<6> are each a group represented by formula II (wherein X<1> is H, cyano, alyl, etc.; and X<2> and X<3> are each alkyl or aryl provided they may combine with each other to form a hetrocycic group contg. O, S, or N), H, halogen, cyano, alkyl, etc., provided that at least one of them is a group represented by formula II and that they may combine with each other to form a ring; M is a di- to tetravalent metal atom; and n is 2-4] and is used for providing an org. electroluminescent element of which the luminous layer comprising a plurality of thin org. compd. layers and sandwiched between a pair of electrodes has at least one layer contg. the material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence (EL) used for a flat light source or a light emitting display.
This is based on an electron injection material for a device and a light emitting device with high luminance and long life.

[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 electrons and holes are recombined 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.
2. Description of the Related Art In recent years, an organic EL in which a thin film containing an organic compound having high fluorescence quantum efficiency that emits light at a low voltage of 10 V or less is laminated.
Devices have been reported and are of interest (see Applied Physics Letters, vol. 51, p. 913, 1987). In this method, high-luminance green light emission is obtained by laminating a metal chelate complex as a phosphor layer and an amine compound as a hole injection layer, and the luminance is several hundred (cd / m ²⁾ under a DC voltage of 6 to 7 V. ), The maximum luminous efficiency is 1.5 (lm)
/ W), which achieves performance close to the practical range.

[0004] However, organic EL devices up to now have improved luminous intensity due to structural improvements, but do not yet have sufficient luminous brightness. In addition, there is a major problem that the stability upon repeated use is poor. This is because, for example, a metal complex such as a tris (8-hydroxyquinolinato) aluminum complex is chemically unstable during electroluminescence, has poor adhesion to a cathode, and does not solve the problem of device deterioration. Still high luminous brightness and luminous efficiency,
There is no light-emitting material having stable light-emitting properties for a long time, and development of a light-emitting material is desired.

It is preferable that the hole injection material of the organic layer of the organic EL element has a high hole injection efficiency from the anode and is capable of efficiently transporting the injected holes toward the light emitting layer. For that purpose, it is required that the ionization potential is small, the hole mobility is large, and the stability is excellent. It is preferable that the electron injecting material is a material having a high electron injection efficiency from the cathode and capable of efficiently transporting the injected electrons toward the light emitting layer. for that purpose,
It is required to have high electron affinity, high electron mobility, and excellent stability.

As hole injection materials proposed up to now, oxadiazole derivatives (US Pat. No. 3,189,397)
447), oxazole derivatives (US Pat. No. 3,25
7,203), hydrazone derivatives (U.S. Pat.
17,462, JP-A-54-59,143, U.S. Pat. No. 4,150,978), triarylpyrazoline derivatives (U.S. Pat.
-93,224, JP-A-55-108,667),
Arylamine derivatives (US Pat. No. 3,180,730)
No. 4,232,103, JP-A-55-1
44,250, JP-A-56-119,132) and stilbene derivatives (JP-A-58-190,953, JP-A-59-195,658).

As electron injection materials, oxadiazole derivatives (Japanese Patent Application Laid-Open No. 2-216793), perinone derivatives (Japanese Patent Application Laid-Open No. 2-289676), and perylene derivatives (Japanese Patent Application Laid-Open No. 2-189890 and Japanese Patent Application Laid-Open No. 3-7991) are disclosed. And quinacridone derivatives (JP-A-6-330031), but the characteristics of electron injection from the cathode to the organic layer of the organic EL device using this electron injection material were not sufficient.

The organic EL devices up to now have improved luminous efficiency by improving the structure, but do not yet have a sufficient device life. In particular, the injection efficiency due to the contact between the cathode metal and the interface of the organic layer is low, and the heat resistance of the organic layer in contact with the electrode has become a serious problem. Therefore, development of an organic material for developing an organic EL device having higher luminous efficiency and a long life is desired.

[0009]

SUMMARY OF THE INVENTION The present invention provides an organic electroluminescence device material having good electron injection efficiency from a cathode and good light emission characteristics, high luminance and high light emission efficiency, little light emission deterioration, and low reliability. It is another object of the present invention to provide an electroluminescent device material having a high property, and to provide an organic EL device having high luminance and a long life using the organic electroluminescent device material of the present invention. As a result of intensive studies by the present inventors, an organic EL device using at least one organic electroluminescent device material represented by the general formula [1] or the general formula [2] has good emission characteristics and electron injection characteristics. It was also found that the stability of the light emission life was excellent, and the present invention was reached.

[0010]

That is, the present invention relates to an organic electroluminescent device material represented by the following general formula [1]. General formula [1]

Embedded image [Wherein, R ^{1 to} R ⁶ each independently represent a substituent represented by the following general formula [2];

Embedded image (Wherein X ¹ is a hydrogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group,
Represents a substituted or unsubstituted heterocyclic group, X ² and X ³
Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, wherein X ² and X ³ are bonded to each other To form a ring that may contain an oxygen, sulfur or nitrogen atom. ), Hydrogen atom, halogen atom, cyano group, nitro group, hydroxyl group, siloxy group, acyl group, carboxylic acid group, sulfonic acid group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted Alkylthio group, substituted or unsubstituted amino group, substituted or unsubstituted aryl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, substituted or unsubstituted And at least one of R ^{1 to} R ⁶
One is a substituent represented by the general formula [2]. R ^{1 to} R ⁶
May be bonded to each other to form a ring that may contain an oxygen atom, a sulfur atom or a nitrogen atom.
M represents a divalent to tetravalent metal atom, and n represents a positive integer of 2 to 4. ]

Further, the present invention relates to the above organic electroluminescent device material, wherein R ¹ is a substituent represented by the general formula [2].

Further, the present invention provides an organic electroluminescent device comprising a light emitting layer or a plurality of organic compound thin film layers including a light emitting layer between a pair of electrodes, wherein at least one of the layers contains the organic electroluminescent device material. It relates to a certain organic electroluminescence element.

Further, the present invention relates to an organic electroluminescence device in which the light emitting layer is a layer containing the above-mentioned organic electroluminescence device material. Further, the present invention relates to an organic electroluminescence device in which at least one layer between the light emitting layer and the cathode is a layer containing the above organic electroluminescence device material.

Further, the present invention relates to an organic electroluminescent device comprising an organic compound thin film layer including a light emitting layer between a pair of electrodes, wherein at least one layer is a layer containing the organic electroluminescent device material. It is.

Further, the present invention relates to an organic electroluminescent device wherein the light emitting layer is a layer containing the above-mentioned organic electroluminescent device material.

Further, the present invention is the organic electroluminescence device wherein at least one layer between the light emitting layer and the cathode is a layer containing the above-mentioned organic electroluminescence device material.

BEST MODE FOR CARRYING OUT THE INVENTION

The substituents of R ^{1 to} R ⁶ of the compound of the present invention will be described. Specific examples of the halogen atom include fluorine, chlorine, bromine, and iodine. Specific examples of the alkyl group preferably have 1 to 20 carbon atoms, and include a methyl group, an ethyl group, a propyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, Stearyl group, trichloromethyl group, trifluoromethyl group, 2,2,2-trifluoroethyl group, 2,2,3,3-tetrafluoropropyl group, 2,2,3,3,3-pentafluoropropyl group ,
There is a 2-methoxyethyl group and the like. Specific examples of the alkoxy group preferably have 1 to 20 carbon atoms, and include methoxy, ethoxy, propoxy, butoxy, trichloromethoxy, trifluoromethoxy, trifluoroethoxy, pentafluoropropoxy, and 2,2. , 3,3-
And a tetrafluoropropoxy group. Specific examples of the alkylthio group preferably have 1 to 20 carbon atoms, such as methylthio, ethylthio, propylthio, butylthio, trichloromethylthio, trifluoromethylthio, trifluoroethylthio, pentafluoropropylthio, , 2,3,3-tetrafluoropropylthio group and the like. Specific examples of the amino group include C 1 -C 1
20 is preferable, and an amino group, a dimethylamino group, a diethylamino group, a diphenylamino group, a ditolylamino group,
And N-naphthyl-1-phenylamino group. Specific examples of the aryl group preferably have 1 to 40 carbon atoms, and include a phenyl group, a tolyl group, a naphthyl group, a biphenyl group, o,
Examples include m, p-terphenyl group, anthranyl group, phenanthrenyl group, fluorenyl group, 9-phenylanthranyl group, 9,10-diphenylanthranyl group, pyrenyl group and the like. Specific examples of the cycloalkyl group preferably have 4 to 20 carbon atoms, and include a cyclopentyl group, a cyclohexyl group, a norbonane group, an adamantane group, a 4-methylcyclohexyl group, a 4-cyanocyclohexyl group, and the like.
Specific examples of the aryloxy group include a group in which the aryl group is bonded via an oxygen atom. Specific examples of the arylthio group include a group in which the above-mentioned aryl group is bonded via a sulfur atom. Specific examples of a heterocyclic group that may contain an oxygen atom or a sulfur atom include pyrrole group, pyrroline group, pyrazole group, pyrazoline group, imidazole group, triazole group, pyridine group, pyridazine group, pyrimidine group, pyrazine group, Triazine group, indole group, purine group, quinoline group, isoquinoline group, sinoline group, quinoxaline group, benzoquinoline group, fluorenone group, dicyanofluorene group, carbazole group, oxazole group, oxadiazole group, thiazole group, thiadiazole group,
Triazole group, imidazole group, benzoxazole group, benzothiazole group, benzotriazole group, benzimidazole group, bisbenzooxazole group, bisbenzothiazole group, bisbenzimidazole group, anthrone group, dibenzofuran group, dibenzothiophene group, anthraquinone group, There are an acridone group and a phenothiazine group.

Specific examples of the substituent which may be added to the above-mentioned groups include halogen atoms of fluorine, chlorine, bromine and iodine, methyl, ethyl, propyl, butyl, s
ec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, stearyl group, trichloromethyl group, trifluoromethyl group, 2,2,2
-Trifluoroethyl group, 2,2,3,3-tetrafluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoro-2 A substituted or unsubstituted alkyl group such as -propyl group, 2,2,3,3,4,4-hexafluorobutyl group, 2-methoxyethyl group, methoxy group, n-butoxy group,
tert-butoxy group, trichloromethoxy group, trifluoroethoxy group, pentafluoropropoxy group, 2,
2,3,3-tetrafluoropropoxy group, 1,1,
1,3,3,3-hexafluoro-2-propoxy group,
A substituted or unsubstituted alkoxy group such as a 6- (perfluoroethyl) hexyloxy group, a cyano group, a nitro group,
Mono- or di-substituted amino groups such as amino group, methylamino group, diethylamino group, ethylamino group, diethylamino group, dipropylamino group, dibutylamino group, diphenylamino group, bis (acetoxymethyl) amino group, bis (acetoxyethyl ) Amino group, bisacetoxypropyl) amino group, acylamino group such as bis (acetoxybutyl) amino group, hydroxyl group, siloxy group, acyl group, methylcarbamoyl group, dimethylcarbamoyl group, ethylcarbamoyl group, diethylcarbamoyl group, propyl carbamoyl Groups, carbamoyl groups such as butylcarbamoyl group and phenylcarbamoyl group, carboxylic acid group, sulfonic acid group, imide group, cyano group, nitro group and the like. Further, the above-described aryl group, cycloalkyl group, aryloxy group, arylthio group, heterocyclic group and the like may be a substituent.

The groups and substituents for X ^{1 to} X ³ are selected from the same groups and substituents as those described above for R ^{1 to} R ⁶ , but are not limited thereto. is not.

In the general formula [1], preferred metal atoms as M are beryllium, zinc, cadmium, magnesium, calcium, cobalt, nickel, iron,
It represents a divalent to tetravalent metal atom such as copper, platinum, palladium, tin, strontium, scandium, aluminum, gallium, indium, zirconium, silicon, and germanium, but is not limited thereto. n differs depending on the valence of the metal atom, and is 2 for a divalent metal, 3 for a trivalent metal, and 4 for a tetravalent metal.

Hereinafter, typical examples of the compound of the general formula [1] or the general formula [3] used in the organic EL device of the present invention will be specifically described, but the present invention is limited to the following typical examples. Not something.

[0022]

[Table 1]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

The compound represented by the general formula [1] of the present invention can be used as a light emitting material or an electron injection material, and may be used alone or in a mixture in the same layer. If necessary, it may be used in combination with another hole or electron injecting compound.
Since the compound of the present invention has good electron transporting ability, electron injecting property from a cathode, and light emitting characteristics, it can be used very effectively in a light emitting layer or an electron injecting layer of an organic EL device.

The 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 may contain a light-emitting material and may further contain a hole-injection material or an electron-injection material in order to transport holes injected from an anode or electrons injected from a cathode to the light-emitting material. The light emitting material may have a hole transporting property or an electron transporting property. The multilayer type includes (anode / hole injection layer / light emitting layer / cathode), (anode / light emitting layer / electron injection layer / cathode), (anode / hole injection layer / light emitting layer / electron injection layer /
There are organic EL elements stacked in a multilayer structure such as a cathode, but the invention is not limited to these.

In the case of a two-layer structure of an organic thin film laminated in the order of (anode / hole injection layer / light emitting layer / cathode), the light emitting layer and the hole injection layer are separated. With this structure, the hole injection efficiency from the hole injection layer to the light emitting layer is improved, and the light emission luminance and the light emission efficiency can be increased. In this case, it is desirable that the light emitting material used in the light emitting layer itself has an electron transporting property, or that an electron injecting material is added to the light emitting layer. In the case of an organic thin film two-layer structure laminated in the order of (anode / light emitting layer / electron injection layer / cathode), the light emitting layer and the electron injection layer are separated. With this structure, the efficiency of electron injection from the electron injection layer to the light-emitting layer is improved, so that light emission luminance and light emission efficiency can be improved. In this case, it is desirable that the light emitting material used for the light emitting layer itself has a hole transporting property, or that a hole injecting material is added to the light emitting layer.

The organic thin film three-layer structure has a light emitting layer, a hole injection layer, and an electron injection layer to improve the efficiency of recombination of holes and electrons in the light emitting layer. As described above, the organic EL element has a multilayer structure, so that it is possible to prevent a decrease in luminance and life due to quenching. Also, a hole injection layer,
The light emitting layer and the electron injection layer may each be formed of two or more layers. When the number of the hole injection layers is two or more, the layer in contact with the anode is called a hole injection layer, the layer between the hole injection layer and the light emitting layer is called a hole transport layer, and the electron injection layer has two layers. In the above cases, the layer in contact with the cathode is often referred to as an electron injection layer, and the layer between the electron injection layer and the light emitting layer is referred to as an electron transport layer.

In the organic EL device of the present invention, in the light emitting layer and the electron injection layer, if necessary, in addition to the compound of the general formula [1], a known light emitting material, doping material, hole injection material, electron injection Materials can be used.

The following compounds may be mentioned as the light emitting material or doping material of the light emitting layer of the organic EL device using the compound of the general formula [1] of the present invention as an electron injection material. Anthracene, naphthalene, phenanthrene, pyrene, tetracene, coronene, chrysene, fluorescein, perylene, phthaloperylene, naphthaloperylene, perinone, phthaloperinone, naphthaloperinone, diphenylbutadiene, tetraphenylbutadiene, coumarin,
Oxadiazole, aldazine, bisbenzoxazoline, bisstyryl, diamine, pyrazine, cyclopentadiene, oxine, aminoquinoline, imine, diphenylethylene, vinylanthracene, diaminocarbazole, pyran, thiopyran, polymethine, merocyanine,
Examples include, but are not limited to, imidazole chelated oxinoid compounds, quinacridone, rubrene, metal complex compounds, and the like, and derivatives thereof. The above materials can be used as a doping material to form a light-emitting layer together with a host material, whereby a light-emitting layer having high light-emitting characteristics can be formed.

Among them, a metal complex compound, a low molecular light emitting compound such as a bisstyryl dye and a diamine dye, a conjugated polymer and the like are exemplified, but not limited thereto. Metal complex compounds include (8-hydroxyquinolinonato) lithium, bis (8-hydroxyquinolinonato) zinc, bis (8-hydroxyquinolinonato) manganese, bis (8-hydroxyquinolinonato) copper, tris (8-hydroxyquinolinonato) aluminum, tris (8-hydroxyquinolinonato) gallium, bis (10
-Hydroxybenzo [h] quinolinato) beryllium, bis (10-hydroxybenzo [h] quinolinato) zinc,
Bis (10-hydroxybenzo [h] quinolinato) magnesium, tris (10-hydroxybenzo [h] quinolinato) aluminum, bis (2-methyl-8-quinolinato) chlorogallium, bis (2-methyl-8-quinolinato) ( o-cresolate) gallium, bis (2-methyl-8-quinolinato) (1-phenolate) aluminum, bis (2-methyl-8-quinolinato) (1-phenolate) gallium, bis (2-methyl-8-quinolinato) (1-naphtholate) aluminum, bis (2-methyl-8-quinolinato) (1-naphtholate) gallium, bis (2-methyl-8-quinolinato) (1-biphenolato) gallium, bis (2- [2-benzo Oxazolinato] phenolate) zinc, bis (2- [2-benzothiazolinato] pheno Over G) zinc, bis (2- [2-
[Benzotriazolinato] phenolate) zinc and the like, but are not limited thereto. These compounds are
They may be used alone or in combination of two or more.

The bisstyryl dye used in the light emitting material includes a phenylene group, a naphthylene group, a biphenylene group, an anthranylene group, a pyrenylene group, a thiophenylene group, a triphenylamino group, an N-ethylcarbazole which may have a substituent. There is a bisstyryl dye having a group as a linking group.

Examples of the diamine dye used in the light emitting material include a phenylene group, a naphthylene group, a biphenylene group, an anthranylene group, a pyrenylene group, a thiophenylene group, a triphenylamino group, and an N-ethylcarbazole which may have a substituent. There is a diamine dye having a group as a linking group. These compounds may be used alone or as a mixture of two or more.

The linking group of the conjugated polymer used in the light emitting material is selected from C, N, H, O, S and 1 to 20.
Any divalent linking group consisting of a chemically rational combination of 0 atoms may be used. Specific linking groups include phenylene, naphthylene, biphenylene, anthranylene, pyrenylene, thiophenylene, triphenylamino, N-ethylcarbazole, and the like. To form Examples of the substituent of these linking groups include the same substituents as in the above general formula [1]. The repeating unit is 2 or more and 10,000 or less.

Representative examples of the conjugated polymer are specifically illustrated, but the present invention is not limited to the following representative examples. Examples of the conjugated polymer include poly (p-phenylene),
Poly (p-phenylenevinylene), poly (2,5-dipentyl-p-phenylenevinylene), poly (2,5-dipentyl-m-phenylenevinylene), poly (2,5-
Dioctyl-p-phenylenevinylene), poly (2.5)
-Dihexyloxy-p-phenylenevinylene), poly (2,5-dihexyloxy-m-phenylenevinylene), poly (2,5-dihexylthio-p-phenylenevinylene), poly (2,5-didecyloxy-p- Phenylene vinylene) poly (2-methoxy-5-hexyloxy-p-phenylene vinylene), poly (2-methoxy-5- (3′-methyl-butoxy) -p-phenylene vinylene, poly (2,5-thienylene) Vinylene), poly (3-n-octyl-2,5-thienylenevinylene),
Poly (1,4-naphthalenevinylene), poly (9,10
-Anthracene vinylene) and their copolymers. These compounds may be used alone or as a mixture of two or more.

The hole injecting material that can be used in the organic EL device of the present invention has the ability to transport holes, has an excellent hole injecting effect on the light emitting layer or the light emitting material, and is produced by the light emitting layer. Compounds that prevent the excitons from transferring to the electron injection layer or the electron injection material and have excellent thin film forming ability. Specifically, phthalocyanine, naphthalocyanine, porphyrin, oxadiazole, triazole,
Imidazole, imidazolone, imidazolethione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole, hydrazone, acylhydrazone, polyarylalkane, stilbene, butadiene, benzidine triphenylamine, styrylamine triphenylamine, diamine triphenyl Examples include amines and the like, derivatives thereof, and high molecular materials such as polyvinyl carbazole, polysilane, and conductive polymers, but are not limited thereto.

The electron injecting material which can be used in combination with the compound of the general formula [1] or the general formula [3] for use in the organic EL device of the present invention has the ability to transport electrons,
A compound that has an excellent electron-injection effect on the light-emitting layer or the light-emitting material, prevents excitons generated in the light-emitting layer from moving to the hole-injection layer or the hole-transport material, and has excellent thin-film forming ability. No. For example, there are fluorenone, anthraquinodimethane, diphenoquinone, thiopyrandioxide, oxadiazole, thiadiazole, triazole, perylenetetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane, anthrone, metal complexes, and derivatives thereof. However, the present invention is not limited to these. These electron injection materials can be used in the same layer as the compound of the general formula [1] or the general formula [3], but the electron injection material formed by the compound of the general formula [1] or the general formula [3] can be used. The electron injection effect can be improved by stacking with a layer. In addition, sensitization can be performed by adding an electron accepting material to the hole injecting material and adding an electron donating material to the electron injecting material.

The hole injecting material, the light emitting material, the doping material and the electron injecting material used together with the organic EL device using the compound of the general formula [1] or [3] of the present invention as the light emitting material are as described above. Can be used. At that time, an appropriate compound can be selected from the compounds of the general formula [1] or the general formula [3] and used as an electron injection material.

In order to improve the stability of the organic EL device obtained according to the present invention with respect to temperature, humidity, atmosphere, etc., a protective layer is provided on the surface of the device or silicon oil is sealed to protect the entire device. It is also possible.

As the conductive material used for the anode, 4
A metal having a work function larger than eV is suitable, and A
u, Pt, Ag, Cu, Al and other metals, metal alloys, IT
Organic conductive resins such as O, NESA or polythiophene or polypyrrole are used.

As the conductive material used for the cathode, 4
A metal or metal alloy having a work function smaller than eV is suitable. As the material, Al, In, Mg, L
i, metal such as Ca, or Mg / Ag, Li / A
1, alloys such as Mg / In. The anode and the cathode may be formed of two or more layers if necessary. The anode and the cathode are manufactured by a known film forming method such as vapor deposition, sputtering, ion plating, and a plasma gun.

In the organic EL device, at least one of the cathode and the anode is preferably 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 by a method such as vapor deposition, sputtering, or ion plating so as to secure a predetermined translucency. The light transmittance of the electrode on the light emitting surface side is desirably 10% or more.

The substrate may be a transparent substrate having mechanical and thermal strengths. Examples thereof include a glass substrate and a plate-like or film-like material such as polyethylene, polyethersulfone, polypropylene, and polyimide. Can be

Each layer of the organic EL device of the present invention is formed by any of dry film forming methods such as vacuum evaporation, sputtering, ion plating and plasma gun methods, and wet film forming methods such as spin coating and dipping. can do. In the case of a copolymer, it is preferable to form a wet film after dissolving in a suitable solvent or the like. The thickness is not particularly limited, but each layer needs to be set to an appropriate 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. Normal film thickness is from 5 nm to 10
The range of μm is suitable, but from 10 nm to 0.2
The range of μm is more preferred.

In the case of the wet film forming method, a material for forming each layer is dissolved or dispersed in a solvent such as chloroform, tetrahydrofuran, dioxane or the like to form a thin film, and any solvent may be used. In any organic layer, an appropriate resin or additive is used to improve film forming properties and prevent pinholes in the film. Examples of such a resin include insulating resins such as polystyrene, polycarbonate, polyarylate, polyester, polyamide, urethane, polysulfone, polymethyl methacrylate, and polymethyl acrylate, and photoconductive resins such as poly-N-vinyl carbazole and polysilane. And conductive resins such as polythiophene and polypyrrole.

As described above, when the compound of the general formula [1] or the general formula [3] is used as an electron injecting material in the organic EL device of the present invention, the electron transport ability and the electron from the cathode surface are obtained. Injection efficiency was improved, and when it was used as a light emitting material, light emission efficiency and light emission luminance could be increased. In addition, since the device has high electron transportability and high electron injection efficiency in the thin film layer, the device is extremely stable, and as a result, a high emission luminance can be obtained with a low driving current. Could also be significantly reduced.

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

[0057]

The present invention will be described below in more detail with reference to examples. Synthesis method of compound (3) In a flask, 24.7 g of α-bromodiphenylmethane was added.
And 16.6 g of triethyl phosphite were added, and 150 ° C.
And stir for 3 hours. The reaction was concentrated in vacuo to give n-
After adding 400 g of hexane, the mixture is cooled at 5 ° C. overnight to precipitate crystals. The obtained crystals were filtered and dried, and 22.7 g of a phosphoric acid ester of Chemical Formula 7 represented by the following chemical structure was obtained.
I got Thereafter, 16.3 g of the phosphoric acid ester of Chemical formula 7, 33.0 g of 8-hydroxy-2-quinolinaldehyde, 8.5 g of sodium ethylate and 150 g of ethanol are put in the flask, and the mixture is stirred under heating and reflux for 30 minutes. After cooling, the mixture was washed with ethanol and purified water in this order, filtered, and then recrystallized from ethyl acetate to obtain 26.7 g of a slightly yellow powder.
Infrared absorption spectrum, NMR spectrum,
As a result of mass spectrometry, it was confirmed that the compound was a compound represented by Chemical Formula 8 represented by the following chemical structure. In addition, in the flask,
16.2 g of the compound of the formula 8, zinc acetate dihydrate 11.0
g and 150 g of ethanol and stirred at 50 ° C. for 2 hours. After cooling, the mixture was washed with ethanol and purified water in this order, filtered, and then recrystallized from ethyl acetate / acetonitrile to obtain g of a slightly yellow powder. Infrared absorption spectrum of this powder, NM
As a result of performing an R spectrum and mass spectrometry, it was confirmed that the compound was Compound (3).

[0058]

Embedded image

[0059]

Embedded image Method for Measuring Light Emission Characteristics of Organic EL Device The electrical characteristics and light emission characteristics (emission brightness, maximum emission brightness) of the organic EL device are measured by measuring the amount of current generated and the emission brightness when a DC or AC voltage is applied to the organic EL device. I do. As the power supply, a constant current power supply or a constant voltage power supply is used, and the generated current is measured with an ammeter. The emission luminance is measured by using a luminance meter for the generated emission. The light emission luminance of the organic EL device of the present invention was measured by LS-100 manufactured by Minolta Camera. The luminous efficiency is as follows (Study Forum of the Next Generation Display Device, “Organic EL Device Development Strategy”, page 207, Science Forum)
Calculated according to the method described in In this example, the surface resistance value is 1
Glass with 0 (Ω / □) ITO electrode was used. Examples in which the organic EL device material of the present invention is used as a light emitting material will be described below.

Example 1 N, N '-(4) was placed on a washed glass plate with ITO electrodes.
-Methylphenyl) -N, N '-(4-n-butylphenyl) -phenanthrene-9,10-diamine was dissolved in tetrahydrofuran, and a hole injection layer having a thickness of 40 nm was obtained by spin coating. Then, compound (3)
Was vacuum-deposited to form a light-emitting layer having a thickness of 40 nm, and magnesium and silver were co-deposited at a ratio of 10: 1 to form a cathode having a thickness of 100 nm to obtain an organic EL device. The light emitting layer and the cathode are
The substrate was deposited at a room temperature in a vacuum of 10 ^-6 Torr. This element has a light emission luminance of 55 (cd /
m ² ), maximum light emission luminance 18,000 (cd / m ² ), 5
Light emission with a light emission efficiency of 2.3 (lm / W) when V was applied was obtained. Next, at a current density of 3 (mA / cm ² ), as a result of a life test in which the device was continuously lit, the initial luminance was 1%.
An emission luminance of / 2 or more was maintained for 10,000 hours or more.

Examples 2 to 17 N, N'-diphenyl-N, N'-dinaphthyl-1,1'-biphenyl-4,4'-diamine was vacuum-deposited on a washed glass plate with an ITO electrode. A hole injection layer having a thickness of 40 nm was obtained. Next, the compounds shown in Table 2 were vacuum-deposited to form a 40-nm-thick light-emitting layer, and magnesium and silver were co-deposited at a ratio of 10: 1 to form a 100-nm-thick cathode to obtain an organic EL device. . The hole injection layer, the light emitting layer and the cathode were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device exhibited the emission characteristics shown in Table 2. Next, as a result of a life test in which the device was continuously caused to emit light at a current density of 3 mA / cm ² , a light emission luminance of 1/2 or more of the initial luminance was maintained for 10,000 hours or more. From this result, it is understood that the organic EL device material of the present invention is an excellent electron-injecting light-emitting material.

[0062]

[Table 2]

Example 18 A glass plate with an ITO electrode and N, N'-diphenyl-N,
N'-dinaphthyl-1,1'-biphenyl-4,4'-
Example 2 Example 2 was repeated except that a metal-free phthalocyanine was vacuum-deposited between a diamine and a hole injection layer having a thickness of 5 nm.
An organic EL device was produced in the same manner as in the above. This element
Light emission having a light emission luminance of 860 (cd / m ² ) at a DC voltage of 5 V, a maximum light emission luminance of 33,000 (cd / m ² ), and a light emission efficiency of 3.3 (lm / W) when 5 V was applied was obtained. next,
As a result of a life test in which the device was continuously lit at a current density of 3 mA / cm ² , luminescence brightness equal to or more than の of the initial brightness was maintained for 20,000 hours or more. The device of this embodiment has a high emission luminance at a DC voltage of 5 V, and is advantageous when driven at a low voltage.

Example 19 An organic EL device was produced in the same manner as in Example 2, except that the cathode was co-evaporated with aluminum and lithium at a ratio of 100: 2. This device has an emission luminance of 770 at a DC voltage of 5 V.
(Cd / m ² ), maximum light emission luminance 42,000 (cd / m ² )
² ) Light emission with a luminous efficiency of 3.8 (lm / W) when 5 V was applied was obtained. Next, as a result of a life test in which the device was continuously caused to emit light at a current density of 3 mA / cm ² , a light emission luminance of 1/2 or more of the initial luminance was maintained for 20,000 hours or more.

Comparative Example 1 An organic EL device was manufactured in the same manner as in Example 2 except that a tris (8-hydroxyquinoline) aluminum complex was used as a light emitting material. This element has a DC voltage of 5
Emission luminance at V 190 (cd / m ² ), maximum emission luminance 1
Light emission with a light emission efficiency of 1.2 (lm / W) when 4,000 (cd / m ² ) and 5 V were applied was obtained.

Next, examples in which the organic EL device material of the present invention is used as an electron injection material will be described below. Example 20 N, N′-diphenyl-N, N′-dinaphthyl-1,1′-biphenyl-4,4′-diamine was vacuum-deposited on a washed glass plate with an ITO electrode to form a positive electrode having a thickness of 40 nm. A hole injection layer was obtained. Next, a tris (8-hydroxyquinoline) aluminum complex and quinacridone were vacuum-deposited at a weight ratio of 50: 1 to form a light-emitting layer having a thickness of 30 nm,
A compound (3) is vacuum-deposited thereon to form an electron injection layer having a thickness of 30 nm, and aluminum and lithium are added in 100:
An electrode having a thickness of 100 nm was formed from the alloy mixed in Step 1 to obtain an organic EL device. The hole injection layer, the light emitting layer, and the electron injection layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device has a light emission luminance of 13 at a DC voltage of 5 V.
90 (cd / m ² ), maximum emission luminance 128,000 (c
d / m ² ), and a luminous efficiency of 11.9 (lm /
Light emission of W) was obtained. Next, as a result of a life test in which the device was continuously lit at a current density of 3 mA / cm ² ,
The emission luminance of 1/2 or more of the initial luminance was maintained for 20,000 hours or more.

Example 21 N, N'-diphenyl-N, N'-dinaphthyl-1,1'-biphenyl-4,4'-diamine was vacuum-deposited on a washed glass plate with an ITO electrode to form a film. A hole injection layer of 40 nm was obtained. Next, the compound (3) was vacuum-deposited to form a light-emitting layer having a thickness of 40 nm.
7) was vacuum-deposited to form an electron-injection layer having a thickness of 30 nm, and an electrode having a thickness of 100 nm was formed using an alloy in which aluminum and lithium were mixed at a ratio of 100: 1 to obtain an organic EL device. The hole injection layer, the light emitting layer, and the electron injection layer are 10 ⁻⁶ To.
Vapor deposition was performed at a substrate temperature of room temperature in a vacuum of rr. This device has a light emission luminance of 660 (cd /
m ² ), maximum emission luminance 37,000 (cd / m ² ), 5
Light emission with an emission efficiency of 4.7 (lm / W) when V was applied was obtained. Next, as a result of a life test in which the device was continuously lit at a current density of 3 mA / cm ² , １ ／ of the initial luminance was obtained.
The above emission luminance was maintained for 10,000 hours or more.

Example 22 Poly (2,5-dipentyl-p-phenylenevinylene)
Was dissolved in tetrahydrofuran, and an organic EL device was produced in the same manner as in Example 2 except that a light-emitting layer having a thickness of 40 nm was obtained by spin coating. This device can emit light with a light emission luminance of 300 (cd / m ² ) at a DC voltage of 5 V, a maximum light emission luminance of 20,000 (cd / m ² ), and a light emission efficiency of 2.9 (lm / W) when 5 V is applied. Was done. Next, 3mA
As a result of a life test in which the device was continuously lit at a current density of / cm ² , a luminescence brightness of 1/2 or more of the initial brightness was 1
Held for more than 000 hours.

Example 23 Washed surface resistance value in place of a glass plate with an ITO electrode
10 (Ω / □) PES film substrate with ITO electrode
Except for using it, the organic EL device was manufactured in the same manner as in Example 2.
Was prepared. This device has a luminance of 12 at a DC voltage of 5V.
00 (cd / m ^Two), Maximum light emission luminance 43,000 (cd
/ M^Two) Luminous efficiency 4.8 (lm / W) when 5V is applied
Was obtained. Next, 3 mA / cm^TwoCurrent density
As a result of a life test in which this device was continuously lit,
Luminance of more than 1/2 of the initial luminance is more than 10,000 hours
Held.

Comparative Example 2 In place of compound (17), 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) -1,3,4
An organic EL device was produced in the same manner as in Example 21, except that -oxadiazole was used. This device can emit light with a peak luminance of 150 (cd / m ² ) at a DC voltage of 5 V, a maximum emission luminance of 11,000 (cd / m ² ), and a luminous efficiency of 1.3 (lm / W) when 5 V is applied. Was done. Next, 3mA
As a result of a life test in which the element was continuously emitted at a current density of / cm ² , the emission luminance was reduced to 以下 or less of the initial luminance in 850 hours.

Comparative Example 3 An organic EL device was prepared in the same manner as in Example 7, except that a tris (8-hydroxyquinoline) aluminum complex was used instead of the compound (17). This device can emit light with a light emission luminance of 300 (cd / m ² ) at a DC voltage of 5 V, a maximum light emission luminance of 15,000 (cd / m ² ), and a light emission efficiency of 1.7 (lm / W) when 5 V is applied. Was done. Next, 3m
As a result of a life test in which the device was continuously caused to emit light at a current density of A / cm ² , the light emission luminance was reduced to half or less of the initial luminance in 2,200 hours.

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, It does not limit the sensitizer, resin, electrode material, and the like, and the element manufacturing method.

[0073]

According to the present invention, by using a compound having excellent electron transporting ability and good injection efficiency from the cathode in the electron injection layer, higher luminous efficiency, higher brightness and longer life can be obtained as compared with the prior art. An organic EL device was obtained. This is because the aggregation of the compound in the formed thin film is small,
This is presumably because deterioration of the device was prevented and stable emission characteristics and electron injection characteristics were obtained.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Satoshi Okutsu 2-3-113 Kyobashi, Chuo-ku, Tokyo Toyo Ink Manufacturing Co., Ltd.

Claims (5)

[Claims] 1. An organic electroluminescent device material represented by the following general formula [1]. General formula [1] [Wherein, R ^{1 to} R ⁶ each independently represent a substituent represented by the following general formula [2]. (Wherein X ¹ is a hydrogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group,
Represents a substituted or unsubstituted heterocyclic group, X ² and X ³
Each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, wherein X ² and X ³ are bonded to each other To form a ring that may contain an oxygen, sulfur or nitrogen atom. ), Hydrogen atom, halogen atom, cyano group, nitro group, hydroxyl group, siloxy group, acyl group, carboxylic acid group, sulfonic acid group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted Alkylthio group, substituted or unsubstituted amino group, substituted or unsubstituted aryl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, substituted or unsubstituted And at least one of R ^{1 to} R ⁶
One is a substituent represented by the general formula [2]. R ^{1 to} R ⁶
May be bonded to each other to form a ring that may contain an oxygen atom, a sulfur atom or a nitrogen atom.
M represents a divalent to tetravalent metal atom, and n represents a positive integer of 2 to 4. ] 2. The organic electroluminescent device material according to claim 1, wherein R ¹ is a substituent represented by the general formula [2]. 3. An organic electroluminescence device comprising a light emitting layer or a plurality of organic compound thin film layers including a light emitting layer between a pair of electrodes, wherein at least one layer contains the organic electroluminescence device material according to claim 1 or 2. Organic electroluminescent element which is a layer to be formed. 4. An organic electroluminescent device wherein the light emitting layer is a layer containing the organic electroluminescent device material according to claim 1. 5. An organic electroluminescent device wherein at least one layer between the light emitting layer and the cathode is a layer containing the organic electroluminescent device material according to claim 1.