JPH09328678A - Organic electroluminescent element material and organic electroluminescent element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an organic electroluminescent element material, comprising a specific compound, excellent in electron transportability and injection efficiency from a cathode, having a higher luminous efficiency and a higher luminance than those of a conventional one and capable of producing a long- lived ectroluminescent element. SOLUTION: This organic electroluminescent element material comprises a compound of the formula [X is O, S, etc.; R<4> to R<8> are each H, a halogen, cyano, nitro, OH, a (substituted)alkyl(thio), a (substituted)aryl(oxy), etc.; M is a bi- or a trivalent metal; (n) is 2 or 3], e.g. a bis[2-(2'-hydroxynaphthyl) benzothiazole]zinc complex. The compound of the formula is obtained by reacting the corresponding OH-containing aromatic heterocyclic ligand with the corresponding metallic compound in a solvent.

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 is composed of a light emitting layer and a pair of counter 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, in order to develop an organic EL device having higher luminous efficiency and long life, development of an organic device material is desired.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides a high-luminance, high-luminance efficiency, less emission deterioration, and reliability by using an organic electroluminescent device material having good electron injection efficiency from the cathode and good emission characteristics. The object is to provide an electroluminescent element material having high properties, and further to provide an organic EL element having high brightness and long life, which uses the present organic electroluminescent element material. As a result of diligent studies by the present inventors, the general formula [1]
It was found that an organic EL element using at least one organic electroluminescent element material represented by the formula (3) has good light emission characteristics and electron injection characteristics, and has excellent stability of light emission life, leading to the present invention.

[0010]

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

[0011]

Embedded image

[Wherein, X is -O-, -S-,> NR
⁹ ,> CR ¹⁰ (R ¹¹ ), R ^{1 to} R ¹¹ are each independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, a hydroxyl group, a siloxy group, an acyl group, a carboxylic acid group or a sulfonic acid group. A substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, A substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, a substituted or unsubstituted heterocyclic group which may contain an oxygen atom or a sulfur atom, and R ^{1 to} R ⁴ and / or R ^{5 to} R ^{The eight} adjacent substituents may combine with each other to form an aromatic ring which may contain an oxygen atom, a sulfur atom or a nitrogen atom. M represents a divalent or trivalent metal atom, and n is 2
Or it represents 3. ]

Furthermore, the present invention provides a compound of the general formula [1]
The above-mentioned organic electroluminescent device material, wherein adjacent substituents of R ^{1 to} R ⁴ and / or R ^{5 to} R ⁸ are bonded to each other to form an aromatic ring which may contain an oxygen atom, a sulfur atom or a nitrogen atom. .

Furthermore, the present invention provides a compound of the general formula [1]
At least one of R ^{1 to} R ⁸ is a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group,
The above organic electroluminescence element material is a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, or a substituted or unsubstituted heterocyclic group which may contain an oxygen atom or a sulfur atom.

The present invention further provides an organic electroluminescent device comprising a light emitting layer or an organic compound thin film layer including a light emitting layer and an electron injection layer between a pair of electrodes, at least one layer containing the organic electroluminescent device material. It is an organic electroluminescence element which is a layer.

The present invention further provides an organic electroluminescent device comprising a light emitting layer or an organic compound thin film layer including a light emitting layer and an electron injection layer between a pair of electrodes, wherein the light emitting layer contains the above organic electroluminescent device material. It is an organic electroluminescence element which is a layer.

Furthermore, the present invention is an organic electroluminescence device comprising a light emitting layer or an organic compound thin film layer including a light emitting layer and an electron injection layer between a pair of electrodes, wherein at least one layer between the light emitting layer and the cathode is as described above. It is an organic electroluminescent element which is a layer containing an organic electroluminescent element material.

BEST MODE FOR CARRYING OUT THE INVENTION

Specific examples of the halogen atom represented by R ^{1 to} R ^{11 in} the compound represented by the general formula [1] of the present invention include fluorine and
There are 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,
Propyl group, butyl group, sec-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
Examples include 3,3-pentafluoropropyl group and 2-methoxyethyl group. Specific examples of the alkoxy group preferably have 1 to 20 carbon atoms, and include methoxy group, ethoxy group, propoxy group, butoxy group, trichloromethoxy group, trifluoromethoxy group, trifluoroethoxy group, pentafluoropropoxy group, 2,2. , 3,3-tetrafluoropropoxy group and the like. Specific examples of the alkylthio group preferably have 1 to 20 carbon atoms, and include methylthio group, ethylthio group, propylthio group, butylthio group, trichloromethylthio group, trifluoromethylthio group, trifluoroethylthio group, pentafluoropropylthio group, and 2 ，
2,3,3-tetrafluoropropylthio group and the like.
As specific examples of the amino group, those having 1 to 20 carbon atoms are preferable, and an amino group, a dimethylamino group, a diethylamino group,
There are a diphenylamino group, a ditolylamino group, an N-naphthyl-1-phenylamino group and the like. 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, an o, m, p-terphenyl group, an anthranyl group, a phenanthrenyl group, a fluorenyl group, and 9-phenyl. Anthranyl 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 the heterocyclic group which may contain an oxygen atom or a sulfur atom include a pyrrole group, a pyrroline group, a pyrazole group, a pyrazoline group, an imidazole group, a triazole group,
Pyridine group, pyridazine group, pyrimidine group, pyrazine group, triazine group, indole group, purine group, quinoline group, isoquinoline group, shinoline 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, bisbenzoxazole group, bisbenzothiazole group, bisbenzimidazole group, anthrone group , Dibenzofuran group, dibenzothiophene group, anthraquinone group, acridone group, phenothiazine group and the like.

Specific examples of the substituent which may be added to the above-mentioned groups include halogen atoms such as fluorine, chlorine, bromine and iodine, methyl group, ethyl group, propyl group, butyl group and 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,
Amino group, methylamino group, diethylamino group, ethylamino group, diethylamino group, dipropylamino group, dibutylamino group, diphenylamino group, and other mono- or di-substituted amino groups, bis (acetoxymethyl) amino group, bis (acetoxyethyl group) ) Amino group, bisacetoxypropyl) amino group, bis (acetoxybutyl) amino group, and other acylamino groups, hydroxyl group, siloxy group, acyl group, methylcarbamoyl group, dimethylcarbamoyl group, ethylcarbamoyl group, diethylcarbamoyl group, propylcarbamoyl group Group, butylcarbamoyl group, carbamoyl group such as phenylcarbamoyl group, carboxylic acid group, sulfonic acid group, imide group and the like. Further, the above-mentioned aryl group, cycloalkyl group, aryloxy group, arylthio group, heterocyclic group which may contain an oxygen atom and a sulfur atom and the like may be a substituent.

In the general formula [1], preferred metal atoms as M are beryllium, zinc, cadmium, magnesium, calcium, cobalt, nickel, iron,
It represents a divalent or trivalent metal atom such as copper, strontium, scandium, aluminum, gallium or indium, but is not limited thereto. n varies depending on the valence of the metal atom, and is 2 in the case of a divalent metal and 3 in the case of a trivalent metal.

Typical examples of the compound of the general formula [1] used in the organic EL device of the present invention will be specifically illustrated below, but the present invention is not limited to the following typical examples.

[0022]

[Table 1]

[0023]

[0024]

[0025]

[0026]

[0027]

The compound represented by the general formula [1] of the present invention can be obtained by reacting an aromatic heterocyclic ligand having a hydroxyl group with a metal compound in a solvent. The reaction is
The ligands used in the metal complex compound of the present invention are synthesized with reference to the following documents to form the metal complex represented by the general formula [1]. (Heterocycles, 16 volumes, 116
5 pages, 1981: Inorganic Chemistry, 27, 4208 pages, 1988: Polymer,
35, 3091, 1994: Journal of Organic Chemistry, 60, 5468, 1995). As the ligand that coordinates to the metal complex, a fused aromatic ring such as naphthalene, anthracene, and phenanthrene, an aromatic ring that may contain an oxygen atom, a sulfur atom or a nitrogen atom in the ring is preferable, and as a substituent, An oxygen atom, an aryl group which may contain a sulfur atom or a nitrogen atom in the ring, or an oxygen atom such as phenoxy, naphthoxy, phenylthio or naphthylthio group,
A group bonded to the aromatic ring via a sulfur atom is preferred. The metal complex having an aromatic ring or a substituent,
The reason why it is suitable for the organic EL device of the present invention is that a compound having a condensed aromatic ring such as naphthalene has a higher heat resistance as a metal complex, and therefore is advantageous in terms of the maximum luminance and the light emission life when the device emits light. Is supposed to be.

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

The organic EL element is an element in which a single-layer or multi-layer organic thin film is formed between an anode and a cathode. In the case of the single layer type, a light emitting layer is provided between the anode and the 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 is an organic EL element having a multilayer structure such as a cathode, but the invention is not limited to these.

If necessary, in addition to the compound of the general formula [1] of the present invention, a light emitting material, a doping material, a hole injecting material or an electron injecting material can be used in the light emitting layer. In the case of the organic thin film two-layer structure in which (anode / hole injection layer / light emitting layer / cathode) is laminated in this order, 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 brightness 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 the electron injecting material is added to the light emitting layer. In the case of an organic thin film two-layer structure in which (anode / light emitting layer / electron injection layer / cathode) is stacked in this order, the light emitting layer and the electron injection layer are separated. With this structure, the electron injection efficiency from the electron injection layer to the light emitting layer is improved, and the light emission brightness and the light emission efficiency can be increased. 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.

Further, the organic thin film three-layer structure has a light emitting layer, a hole injecting layer, and an electron injecting layer to improve the efficiency of recombination of holes and electrons in the light emitting layer. As described above, the organic EL element having a multi-layered structure can prevent a decrease in brightness and life due to quenching. In such a device having a multilayer structure, if necessary, a light emitting material, a doping material, a hole injecting material for carrying carriers, and an electron injecting material can be used in combination. Also, a hole injection layer, a light emitting layer,
The electron injection layer may be formed of two or more layers. When the hole injection layer has two or more layers, the layer in contact with the anode is called the hole injection layer, the layer between the hole injection layer and the light emitting layer is called the hole transport layer, and the electron injection layer has two layers. In the above cases, the layer in contact with the cathode is often called an electron injection layer, and the layer between the electron injection layer and the light emitting layer is called an electron transport layer.

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

Examples of the light emitting material or the 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 the electron injecting material include the following compounds. 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 these, metal complex compounds, low molecular weight luminescent compounds such as bisstyryl dyes and diamine dyes, conjugated polymers and the like can be mentioned, but the invention is 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.

Examples of the bisstyryl dye used in the light emitting material include a phenylene group which may have a substituent, a naphthylene group, a biphenylene group, an anthranylene group, a pyrenylene group, a thiophenylene group, a triphenylamino group and N-ethylcarbazole. There is a bisstyryl dye having a group as a linking group. Table 2 specifically illustrates typical examples of the bisstyryl dye used in the light emitting layer of the organic EL device of the present invention.
It is not limited to the following representative examples. These compounds may be used alone or as a mixture of two or more.

[0037]

[Table 2]

Examples of the diamine dye used in the light emitting material include a phenylene group which may have a substituent, a naphthylene group, a biphenylene group, an anthranylene group, a pyrenylene group, a thiophenylene group, a triphenylamino group and N-ethylcarbazole. There is a diamine dye having a group as a linking group. Table 3 specifically shows typical examples of the diamine dye used in the light emitting layer of the organic EL device of the present invention, but the present invention is not limited to the following typical examples. These compounds are
They may be used alone or in combination of two or more.

[0039]

[Table 3]

[0040]

[0041]

The linking group of the conjugated polymer used for the light emitting material is 1 to 20 selected from C, N, H, O and S.
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 will be 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-phenylene vinylene), poly (2,5-dipentyl-p-phenylene vinylene), poly (2,5-dipentyl-m-phenylene). Vinylene), poly (2,5-dioctyl-p-phenylenevinylene), poly (2,5-dihexyloxy-p-phenylenevinylene), poly (2,5-dihexyloxy-m-phenylenevinylene), poly (2 , 5-Dihexylthio-p-phenylene vinylene), 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) Le-2,5-
Thienylene vinylene), poly (1,4-naphthalene vinylene), 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 in the light emitting layer. Examples of the compound include a compound capable of preventing the excitons from moving to the electron injection layer or the electron transport material and having an 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 that can be used in combination with the compound of the general formula [1] used in the organic EL device of the present invention has an ability to transport electrons and is excellent in electron injecting to the light emitting layer or the light emitting material. A compound which has an effect and prevents excitons generated in the light emitting layer from moving to the hole injecting layer or the hole transporting material and has an excellent thin film forming ability can be mentioned. For example, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxadiazole, thiadiazole, triazole, perylenetetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane,
Examples include, but are not limited to, anthrones, metal complexes, and derivatives thereof. These electron injecting materials can be used in the same layer as the compound of the general formula [1]. However, the electron injecting material should be laminated with an electron injecting layer formed of the compound of the general formula [1] to improve the electron injecting effect. Can also. 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.

Each of the above compounds is used as 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] of the present invention as the light emitting material. be able to. At that time,
An appropriate compound can be selected from the compounds of the general formula [1] and used as an electron injection material.

In order to improve the stability of the organic EL device obtained by the present invention against temperature, humidity, atmosphere, etc., a protective layer is provided on the surface of the device or silicon oil or the like is enclosed to protect the entire device. It is also possible to do so.

The conductive material used for the anode is 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.

The conductive material used for the cathode is 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, it is preferable that at least one of the cathode and the anode 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 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 one having mechanical and thermal strength, and examples thereof include a glass substrate, a plate-like or film-like one such as polyethylene, polyether sulfone, polypropylene and polyimide. To be

For forming each layer of the organic EL device of the present invention, any one of dry film forming methods such as vacuum deposition, sputtering, ion plating, and plasma gun method, and wet film forming methods such as spin coating and dipping is applied. 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 film thickness is not particularly limited, but each layer needs to be set to an appropriate film thickness. If the film thickness is too thick, 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 preferable.

In the case of the wet film forming method, the material 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] is used as the electron injecting material in the organic EL device of the present invention, the electron transporting ability and the electron injecting efficiency from the cathode surface are improved. When used as a light emitting material, the light emitting efficiency and the light emitting brightness 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 TV or a flat light-emitting body.
It can be applied to light sources such as copiers and printers, light sources such as liquid crystal displays and instruments, display boards, marker lights, etc., and its industrial value is very large.

[0055]

The present invention will be described in more detail based on the following examples. Method for synthesizing compound (17) 2- (2'-hydroxynaphthyl) benzothiazole g in powder form is put in 200 ml of ethanol and dissolved by stirring at 65 ° C. After dissolution, anhydrous zinc acetate (g) was added and the mixture was stirred at 65 ° C. for 3 hours, and the precipitated crystals were separated by filtration, washed with methanol and dried to obtain g of yellow fluorescent powder. As a result of elemental analysis, molecular weight analysis and NMR spectrum analysis, it was confirmed to be compound (17). Example 1 N, N '-(4-methylphenyl) -N, on a glass plate with an ITO electrode having a washed surface resistance value of 10 (Ω / □)
N '-(4-n-butylphenyl) -phenanthrene-
Dissolve 9,10-diamine in tetrahydrofuran,
A hole injection layer having a film thickness of 40 nm was obtained by spin coating. Then, a light-emitting layer having a thickness of 40 nm of tris (8-hydroxyquinoline) aluminum complex was formed, and the compound (1) was vacuum-deposited to form an electron injection layer having a thickness of 30 nm. An electrode having a thickness of 100 nm was formed from the mixed alloy to obtain an organic EL device. The light emitting layer and the electron injection layer were deposited at a substrate temperature of room temperature in a vacuum of 10 ⁻⁶ Torr. This device has a maximum brightness of 13,500 (cd / m ² ) at a DC voltage of 5 V (60 (cd / m ² )).
² ) Light emission with a luminous efficiency of 1.6 (lm / W) when 5 V was applied was obtained. Next, as a result of a life test in which the device was continuously made to emit light at a current density of 3 (mA / cm ² ), a light emission luminance of ½ or more of the initial luminance was maintained for 10,000 hours or more.

Example 2 An organic EL device was produced in the same manner as in Example 1 except that the compound (18) was used in the electron injection layer. This element has a maximum brightness of 1 (85 cds / m ² ) at a DC voltage of 5V.
Light emission of 6,500 (cd / m ² ) and a light emission efficiency of 1.9 (lm / W) when 5 V was applied was obtained. Next, 3 (mA
As a result of a life test in which the device was made to continuously emit light at a current density of / cm ² ), the emission brightness of ½ or more of the initial brightness was maintained for 10,000 hours or more.

Example 3 N, N'-diphenyl-N, N'-dinaphthyl-1,1'-biphenyl-4,4 was washed on a glass plate with an ITO electrode having a surface resistance value of 10 (Ω / □). '-Diamine was vacuum-deposited to obtain a hole injection layer having a film thickness of 40 nm. Then
Tris (8-hydroxyquinoline) aluminum complex is vacuum-deposited to form a light-emitting layer having a thickness of 40 nm, and compound (27) is vacuum-deposited to form an electron-injection layer having a thickness of 30 nm. An electrode having a thickness of 100 nm was formed from the alloy mixed in 1 to obtain an organic EL device. The hole injection layer, the light emitting layer and the electron injection layer are 10 ⁻⁶ Torr.
In vacuum, the substrate was deposited at room temperature. This element
65 (cd / m ² ) at 5V DC, maximum brightness of 15.5
00 (cd / m ² ), luminous efficiency 1.7 when 5 V is applied
Light emission of (lm / W) was obtained. Next, 3 mA / cm ²
As a result of a life test in which the device was made to continuously emit light at a current density of, the emission brightness of ½ or more of the initial brightness was 10,000.
It was kept for more than 0 hours.

Example 4 A glass plate with an ITO electrode and N, N'-diphenyl-N,
N'-dinaphthyl-1,1'-biphenyl-4,4'-
Example 3 except that a metal-free phthalocyanine is vacuum-deposited with a diamine to form a hole injection layer having a film thickness of 5 nm.
An organic EL device was produced in the same manner as in the above. This element
100 (cd / m ² ) at DC voltage 5V, maximum brightness 13,
000 (cd / m ² ), luminous efficiency at 5V application of 1.6
Light emission of (lm / W) was obtained. Next, 3 mA / cm ²
As a result of a life test in which the device was made to continuously emit light at a current density of, the emission brightness of ½ or more of the initial brightness was 20,000.
It was kept for more than 0 hours.

Example 5 N, N'-diphenyl-N, N'-dinaphthyl-1,1'-biphenyl-4,4 was washed on a glass plate with an ITO electrode having a surface resistance value of 10 (Ω / □). '-Diamine was vacuum-deposited to obtain a hole injection layer having a film thickness of 40 nm. Then
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, and the compound (22) was vacuum-deposited thereon to form a light-emitting layer having a thickness of 30 nm. An electron injection layer was formed, and an electrode having a thickness of 100 nm was formed from an alloy in which aluminum and lithium were mixed at 100: 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 emitted 1250 (cd / m ² ), a maximum luminance of 143,000 (cd / m ² ), and a luminous efficiency of 13.2 (lm / W) when 5 V was applied at a DC voltage of 5V. Next, 3m
As a result of a life test in which the device was continuously made to emit light at a current density of A / cm ^2, a luminance of ½ or more of the initial luminance was retained for 20,000 hours or more.

Example 6 A cleaned glass electrode with an ITO electrode having a surface resistance value of 10 (Ω / □)
N, N'-diphenyl-N, N'-dinaf on a lath plate
Cyl-1,1'-biphenyl-4,4'-diamine is true
Vapor deposition was performed to obtain a hole injection layer having a film thickness of 40 nm. Then
The compound (A-8) in Table 2 was vacuum-deposited to a film thickness of 40 nm.
Of the compound (43) is vacuum-deposited on it.
To form an electron injection layer with a thickness of 30 nm,
100n thick with an alloy of 100: 1 and lithium
An electrode of m was formed to obtain an organic EL device. Hole injection layer,
10 for the light emitting layer and the electron injecting layer^-6In the vacuum of Torr,
Deposition was carried out under the condition that the substrate temperature was room temperature. This element is
550 (cd / m at 5V) ^Two), Maximum brightness of 39,000
(Cd / m^Two) Luminous efficiency at 5 V applied 4.4 (lm
/ W) emission was obtained. Next, 3 mA / cm^TwoCurrent
Based on the density, the result of a life test in which this device was made to continuously emit light
As a result, when the emission brightness of more than 1/2 of the initial brightness is 10,000
Held for more than a while.

Example 7 N, N'-diphenyl-N, N'-dinaphthyl-1,1'-biphenyl-4,4 was washed on a glass plate with an ITO electrode having a surface resistance value of 10 (Ω / □). '-Diamine was vacuum-deposited to obtain a hole injection layer having a film thickness of 40 nm. Then
The compound (A-11) in Table 2 was vacuum-deposited to a film thickness of 40 n.
m, a compound (22) was vacuum-deposited thereon to form an electron injecting layer having a thickness of 30 nm, and an alloy in which aluminum and lithium were mixed at a ratio of 100: 1 had a thickness of 100.
An electrode of nm was formed 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 maximum brightness of 15 at 3300 (cd / m ² ) at a DC voltage of 5V.
Luminous efficiency at 1,000 (cd / m ² ) and 5 V applied 1
A light emission of 3.4 (lm / W) was obtained. Next, 3mA /
As a result of a life test in which this device was made to continuously emit light at a current density of cm ^2, a luminance of 1/2 or more of the initial luminance was 1
Hold for more than 5,000 hours.

Example 8 A compound (24) was vacuum-deposited on the light emitting layer to form a film having a thickness of 30.
Example 7 except that an electron-transporting layer having a thickness of 10 nm is formed, a tris (8-hydroxyquinoline) aluminum complex is vacuum-deposited thereon to form an electron-injecting layer having a thickness of 10 nm, and the electron-injecting layer is laminated. An organic EL device was produced by the same method as described above. This element is 3100 (cd / m at 5V DC voltage)
² ), the maximum luminance was 101,000 (cd / m ² ), and blue light emission with a luminous efficiency of 15.8 (lm / W) when 5 V was applied was obtained. Next, as a result of a life test in which this device was continuously made to emit light at a current density of 3 mA / cm ² ,
A light emission brightness of 2 or more was maintained for 20,000 hours or more, and the light emission life was improved.

Example 9 Poly (2,5-dipentyl-p-phenylene vinylene)
Was dissolved in tetrahydrofuran, and an organic EL device was prepared in the same manner as in Example 7, except that a light emitting layer having a thickness of 40 nm was obtained by spin coating. This element has a maximum brightness of 21,50 with a DC voltage of 5 V and a luminance of 150 (cd / m ² ).
0 (cd / m ² ), luminous efficiency at 5V application of 4.5 (l
Light emission of m / W) 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 10,000 hours or more.

Example 10 An organic EL device was manufactured in the same manner as in Example 7, except that a cleaned PES film substrate with an ITO electrode having a surface resistance value of 15 (Ω / □) was used instead of the glass plate with an ITO electrode. Was produced. This element is 2100 (c
d / m ² ), maximum brightness 93,000 (cd / m ² ), 5
Light emission with a light emission efficiency of 14.7 (lm / W) when V was applied was obtained. Next, as a result of a life test in which this device was continuously made to emit light at a current density of 3 mA / cm ² ,
Emission brightness of 2 or more was maintained for 10,000 hours or more.

Comparative Example 1 2- (4'-tert-butylphenyl) -5- (4 "-biphenyl) -1,3,4-in place of the compound (22)
An organic EL device was produced in the same manner as in Example 7 except that oxadiazole was used. This element has a maximum luminance of 18,500 with a DC voltage of 5 V and a voltage of 210 (cd / m ² ).
(Cd / m ² ), luminous efficiency at 5 V applied of 2.0 (lm
/ W). Next, as a result of a life test in which this device was made to continuously emit light at a current density of 3 mA / cm ² , the emission brightness decreased to ½ or less of the initial brightness in 1300 hours.

Comparative Example 2 Instead of the compound (22), tris (8-hydroxyquinolin) was used.
N) Same as Example 7 except that aluminum complex is used
An organic EL device was manufactured in the same manner. This element is DC
1100 (cd / m at voltage 5V^Two), Maximum brightness 55,0
00 (cd / m ^Two) Luminous efficiency at 5 V applied 4.8
A green light emission of (lm / W) was obtained. Next, 3mA / c
m^TwoLifetime of continuous light emission of this device at current density of
As a result of the test, when the emission luminance is 1/2 or less of the initial luminance, 210
It decreased at 0 hours.

The organic EL device of the present invention achieves improvement of luminous efficiency, luminous brightness and prolongation of life, and is used together with a light emitting material, a doping material, a hole injecting material, an electron injecting material, and an increasing material. The sensitizer, the resin, the electrode material, and the like, and the element manufacturing method are not limited.

[0068]

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 probably because the device was prevented from deterioration and stable electron injection characteristics were obtained.

Front Page Continuation (72) Inventor Satoshi Okutsu 2-3-3 Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd.

Claims (6)

[Claims] 1. An organic electroluminescence device material comprising a compound represented by the following general formula [1]. General formula [1] [Wherein X is -O-, -S-,> NR ⁹ ,> CR ¹⁰
(R ¹¹ ), R ^{1 to} R ¹¹ are each independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, a hydroxyl group, a siloxy group, an acyl group, a carboxylic acid group, a sulfonic acid group, a substituted or unsubstituted group. An alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group,
A substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group,
A substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, a substituted or unsubstituted heterocyclic group which may contain an oxygen atom or a sulfur atom, R
Adjacent substituents of ^{1 to} R ⁴ and / or R ^{5 to} R ⁸ may be bonded to each other to form an aromatic ring which may contain an oxygen atom, a sulfur atom or a nitrogen atom. M represents a divalent or trivalent metal atom, and n represents 2 or 3. ] 2. The compound of the general formula [1] may contain an oxygen atom, a sulfur atom or a nitrogen atom in which adjacent substituents R ^{1 to} R ⁴ and / or R ^{5 to} R ⁸ are bonded to each other. The organic electroluminescent device material according to claim 1, which forms an aromatic ring. 3. A compound of the general formula [1], wherein at least one of R ^{1 to} R ⁸ is a substituted or unsubstituted aryl group,
A substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, a substituted or unsubstituted heterocyclic group which may contain an oxygen atom or a sulfur atom. Or 2
The organic electroluminescent element material described. 4. An organic electroluminescence device comprising a light emitting layer or an organic compound thin film layer including a light emitting layer and an electron injection layer between a pair of electrodes, at least one of which is an organic electroluminescence device material according to claim 1. An organic electroluminescence element which is a layer containing. 5. An organic electroluminescent device comprising a light emitting layer or an organic compound thin film layer including a light emitting layer and an electron injecting layer between a pair of electrodes, wherein the light emitting layer is an organic electroluminescent device material according to claim 1. An organic electroluminescence element which is a layer containing. 6. An organic electroluminescent device comprising a light emitting layer or an organic compound thin film layer including a light emitting layer and an electron injection layer between a pair of electrodes, wherein at least one layer between the light emitting layer and the cathode is formed. 3. An organic electroluminescence device, which is a layer containing the organic electroluminescence device material according to item 3.