JPH10284252A - Organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a driving voltage rise or lowering of luminance during element driving and appearance and growth of a current leakage and a non- luminous part and provide an organic EL element with its high heat resistance and high luminance by having at least one or more organic compound layers and at least one layer of these organic layers having a trriaryl amine polymer. SOLUTION: A particular organic compound is expressed by a formula, wherein R1 to R6 respectively denote H, an alkyl group, alkoxy group, a 3-phenyl group, a phenoxy group, 3-phenyl group, a phenoxy group, an aryl amino group, or diarylamino group. However, at least one of R1 to R6 is a 3-phenyl group, an aryl amino group, or di-aryl amino group. Since this compound is employed for a positive hole injection layer or a positive hole injection transport layer, thin-film property is good, and uniform light emission is made possible. High-temperature driving can be withstood, light is efficiently emitted at a low driving voltage or current, and rise of the driving voltage is small during continuous driving.

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) device, and more particularly, to a device that emits light by applying an electric field to a laminated thin film made of an organic compound. More specifically, the present invention relates to an organic electroluminescent device having a low driving voltage, stable driving, stable light emission, high display quality, and high heat resistance by using a specific triarylamine polymer for a hole injection layer.

[0002]

2. Description of the Related Art An organic EL device has a structure in which a thin film containing a fluorescent organic compound is sandwiched between a cathode and an anode. This is an element that emits light by utilizing light emission (fluorescence / phosphorescence) when the exciton is deactivated.

The characteristics of the organic EL device are that it can emit a high-luminance surface light of about 100 to 100,000 cd / m ² at a low voltage of 10 V or less, and can change the color from blue to red by selecting the kind of fluorescent substance. Is possible.

[0004] On the other hand, the problems of the organic EL are that the luminescent life is short, the storage durability and the reliability are low.

(1) Physical change of organic compound (Nonuniformity of interface occurs due to growth of crystal domains, etc., which causes deterioration of charge injection capability, short circuit, and dielectric breakdown of the element. Particularly, low molecular weight of 500 or less. When a molecular compound is used, the appearance and growth of crystal grains occur, and the film properties are significantly reduced.
Further, even if the interface of ITO or the like is rough, remarkable crystal grains appear and grow, which causes a decrease in luminous efficiency and a leakage of current, resulting in no light emission. It also causes a dark spot which is a partially non-light emitting portion. )

(2) Oxidation and exfoliation of cathode (Na, K, Li, Mg, Ca, Al, etc. have been used as metals having a small work function to facilitate electron injection. It reacts with moisture or oxygen in the atmosphere, or the organic layer and the cathode peel off, making it impossible to inject charges.Especially when spin-coating using a polymer compound etc., residual solvent and moisture during film formation And decomposition products accelerate the oxidation reaction of the electrode, causing the electrode to peel off and to generate a partial non-light emitting portion.)

(3) The luminous efficiency is low and the amount of generated heat is large. (Since a current is passed through the organic compound, the organic compound must be placed under a high electric field strength, and it cannot escape heat generation.
Due to the heat, the element is deteriorated or broken due to melting, crystallization, thermal decomposition, etc. of the organic compound. )

(4) Photochemical and electrochemical changes of the organic compound layer (When an electric current is applied to the organic substance, the organic substance is degraded, and defects such as current traps and exciton traps are generated. Element deterioration such as reduction occurs).

Further, practical light emitting devices are used in various environments, but particularly in a high temperature environment, rearrangement of organic molecules such as crystallization, movement and diffusion of organic substances, which are physical changes of organic compounds, occurs. This causes deterioration of display quality and destruction of elements.

Also, the anode and cathode interfaces, which are the interface between the organic material and the inorganic material, particularly the anode interface, have a great effect on the film properties of the organic material layer at the time of film formation, and depending on the state, the organic material layer may be uneven on the anode. Problems such as formation of a film or failure to form a good interface occur.

For this reason, it has been reported that a material such as phthalocyanine, polyphenylenevinylene, a polythiophene vapor-deposited film, or an amine polymer is used for an anode interface of an organic EL light emitting device. However, phthalocyanine (US Pat. No. 4,720,432 or JP-A-63-432)
The use of phthalocyanine itself is microcrystalline and promotes the crystallization of the material placed thereon,
Even if it is good in the initial state, it causes dark spots and uneven light emission in the long term, which is not preferable. In addition, since polyphenylene vinylene uses a wet process such as spin coating, the oxidization of the electrode is rapid because impurities such as moisture and the like in the air are involved, and ionic impurities such as leaving groups when converting from the precursor are mixed. This causes a significant deterioration in luminance and an increase in driving voltage.

The polythiophene vapor-deposited film has a large degree of variation in the degree of polymerization of polythiophene and the time of vapor deposition, has low reproducibility in producing a favorable device, and has a film thickness because polythiophene itself has light absorption in the visible light region. It is difficult to increase the thickness of the ITO, and problems such as insufficient modification of the surface state of the ITO occur. Examples of the amine-based multimer include dendrimer materials (JP-A-4-308688) and tetraamine materials (US Pat. No. 4,396,627).
Although triamine materials (Japanese Patent Application Laid-Open No. 8-193191) have been reported, sufficient heat resistance, in particular, uniformity and stability of a film on an anode in a high-temperature storage state have not been obtained.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide various luminescent colors having high reliability and luminous efficiency, particularly by using optical and electronic functional materials having little physical change, photochemical change and electrochemical change. And to provide an organic EL device.

Further, an organic thin film formed by vapor deposition of a compound having a high amorphous property and a high compatibility with the anode is used to increase the driving voltage and decrease the luminance when driving the device, leak current, and partially emit light. An object of the present invention is to provide an organic EL device which suppresses the appearance and growth of portions, has a small decrease in luminance, has high reliability such as high heat resistance, and has high luminance.

Another object of the present invention is to provide an organic EL device using a multilayer film, which has an optimum work function for a positive electrode and an organic material to be combined and has high heat resistance.

[0016]

This and other objects are achieved by the present invention which is defined below as (1) to (4). (1) An organic EL device having at least one or more organic compound layers, wherein at least one of the organic material layers contains a compound represented by the following formula (I).

[0017]

Embedded image

(In the formula (I), R ₁ , R ₂ , R ₃ , R ₄ , R ₅
And R ₆ each represent a hydrogen atom, an alkyl group, an alkoxy group, a 3-phenyl group, a phenoxy group, an arylamino group or a diarylamino group. Where R ₁ , R ₂ ,
At least one of R ₃ , R ₄ , R ₅ and R ₆ is a 3-phenyl group, an arylamino group or a diarylamino group. (2) An organic EL device having at least a hole injection / transport layer and a light-emitting layer as the organic compound layer, wherein the hole injection / transport layer contains the compound of the above (1). (3) An organic EL device having a hole injection layer and a light emitting layer as the organic compound layer, wherein the hole injection layer contains the compound of the above (1). (4) The organic EL device according to any one of the above (1) to (3), wherein the light emitting layer contains a hole injecting and transporting compound and an electron injecting and transporting compound.

[0019]

In the organic EL device of the present invention, since the compound represented by the above formula (I) is used in the hole (hole) injecting layer or the hole injecting and transporting layer, the organic EL device has a good thin film property and can emit light uniformly without unevenness. It is. It is stable in the atmosphere for more than one year and does not crystallize. Further, in order to optimize the hole injection efficiency, it is characterized by having a triarylamine multimer specific to the molecular structure. Also, it can withstand high temperature driving and emits light efficiently with low driving voltage and low driving current. Further, in the organic EL device of the present invention, the driving voltage does not increase during continuous driving. The maximum emission wavelength of the EL device of the present invention is about 400 to 700 nm.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The organic EL device of the present invention has an organic compound layer, and at least one organic compound layer contains a compound having a skeleton represented by the above formula (I).

Describing the above formula (I), R ₁ ,
R ₂ , R ₃ , R ₄ , R ₅ and R ₆ represent a hydrogen atom, an alkyl group, an alkoxy group, a 3-phenyl group, a phenoxy group, an arylamino group or a diarylamino group. R ₁ and R ₃ and R ₅ , and R ₂ and R ₄ and R
₆ are usually the same but may be different. Examples of the alkyl group include a linear or branched alkyl group having 1 to 6 carbon atoms. As the alkoxy group, those having 1 to 6 carbon atoms in the alkyl portion are preferable, and specific examples include a methoxy group, an ethoxy group, and a t-butoxy group. The phenyl group may have a substituent. Examples of such a substituent include an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group, a methoxy group, an ethoxy group, and the like. And an alkoxy group having 1 to 6 carbon atoms, a phenoxy group and the like. These substituents preferably have a substituent at the 3-position of the mother skeleton. As the arylamino group or the diarylamino group,

[0022]

Embedded image

[0023] Ar ₁ and Ar
₂ represents a phenyl group, an (o, m, p) biphenyl group or an α, β-naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group or a perylenyl group, each of which is an alkyl group having 1 to 3 carbon atoms; It may be substituted with an aryl group, an alkoxy group, an amino group or a benzoyl group. R ₇ is an alkyl group having 1 to 5 carbon atoms.

It is to be noted that carbon atoms which substitute Ar ₁ and Ar ₂ have 1 carbon atom.
Examples of the alkyl groups (1) to (3) include a methyl group, an ethyl group, and a propyl group. The aryl group that substitutes for Ar ₁ and Ar ₂ may be a monocyclic or polycyclic group, Those having 6 to 20 are preferred. In particular,
Examples include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group and a pyrenyl group, and a phenyl group is particularly preferred. These aryl groups may be further substituted, and examples of such a substituent include an alkyl group, an aryl group, an alkoxy group, and an aryloxyl group.
The alkoxy group that substitutes for Ar ₁ and Ar ₂ preferably has 1 to 6 carbon atoms in the alkyl portion, and specific examples include a methoxy group, an ethoxy group, and a t-butoxy group. These may be further substituted. A
The amino group which substitutes for r ₁ and Ar ₂ may be unsubstituted or may have a substituent. Examples of the amino group having a substituent include a dimethylamino group, a diethylamino group, a diphenylamino group, and a phenylbiphenylamino group. A diarylamino group having the above-mentioned Ar ₁ , Ar ₂ , R ₇ such as a bis (biphenyl) amino group, an alkylarylamino group,
And a diarylamino group. The benzoyl group may have a substituent, such a substituent,
Examples are the same as those described for the aryl group.

At least one of R _{1 to} R ₆ , especially 2 to 6, and more preferably 3 to 6, must be a 3 phenyl group and / or an arylamino group and / or a diarylamino group. .

Preferred specific examples of the above formula (I) are shown below.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Table 4]

[0031]

[Table 5]

[0032]

[Table 6]

The compound of the present invention can be provided by condensing a halogenated aromatic with a primary or secondary aromatic amine by an Ullmann reaction. In particular, the compound can be preferably synthesized by condensing an aryl iodide compound and an arylamino or diarylamino compound by an Ullmann reaction.

The compound of the present invention can be analyzed by mass spectrometry, infrared absorption spectrum (IR), and ¹ H nuclear magnetic resonance spectrum (NM).
R) and the like.

These compounds of the present invention are 640 to 20
It has a molecular weight of about 00, has a high melting point of 190-300 ° C. or higher, shows a high glass transition temperature of 80-200 ° C.,
Form a stable amorphous state even at room temperature or higher by transparent vacuum deposition etc., and obtain a smooth and good film,
And it is maintained for a long time. It should be noted that some of the compounds of the present invention do not show a melting point and may exhibit an amorphous state even at a high temperature. Therefore, a thin film can be formed by itself without using a binder resin.

The EL device of the present invention has at least one organic compound layer, and at least one organic compound layer contains the compound of the present invention. FIG. 1 shows a configuration example of the organic EL element of the present invention. The organic EL device shown in FIG. 1 has an anode 3, a hole injection / transport layer 4, a light emitting layer 5, an electron injection / transport layer 6, and a cathode 7 in that order. Conversion filter 9, the organic EL
An organic EL color display is obtained by sequentially laminating and forming the element, the sealing layer 10, and the cover 11.

The light emitting layer has a function of injecting holes (holes) and electrons, a function of transporting them, and a function of generating excitons by recombination of holes and electrons. The hole injection transport layer is
The electron injection transport layer has a function of facilitating injection of holes from the anode, a function of stably transporting holes, and a function of hindering the transport of electrons. These layers have the function of stably transporting electrons and the function of hindering the transport of holes.These layers increase and confine holes and electrons injected into the light emitting layer, optimize the recombination region, Improve luminous efficiency. The electron injecting / transporting layer and the hole injecting / transporting layer are provided as necessary in consideration of the height of each function of electron injection, electron transport, hole injection, and hole transport of the compound used in the light emitting layer. For example, when the compound used for the light-emitting layer has a high hole-injection-transport function or an electron-injection-transport function, the light-emitting layer may be provided without the hole-injection-transport layer or the electron-injection-transport layer. It can be configured to also serve as a transport layer. In some cases, neither the hole injection transport layer nor the electron injection transport layer may be provided. In addition, the hole injection / transport layer and the electron injection / transport layer may be separately provided in a layer having an injection function and a layer having a transport function.

Further, by controlling the film thickness in consideration of the carrier mobility and carrier density (determined by ionization potential and electron affinity) of the combined light emitting layer, electron injection transport layer and hole injection transport layer. ,
It is possible to freely set a recombination region and a light emission region, and it is possible to design a light emission color, control a light emission luminance and a light emission spectrum by an interference effect between both electrodes, and control a spatial distribution of light emission.

The case where the compound of the present invention is used for a hole injection transport layer will be described. The hole injection transport layer may be formed by depositing the compound of the present invention or dispersing the compound in a resin binder and coating. In particular, a good amorphous film can be obtained by vapor deposition.

When the compound of the present invention is used in the hole injecting and transporting layer, the fluorescent substance used in the light emitting layer may be selected from those having fluorescence of a longer wavelength. One of the fluorescent substances used in combination with the compound
What is necessary is just to select suitably from a kind or more. In such a case, the compound of the present invention can be used also in the light emitting layer.

The hole injecting and transporting layer may be combined with one or more hole injecting and transporting materials. It is particularly preferred that the hole injecting and transporting materials to be combined are laminated on the ITO in ascending order of ionization potential, for example, a hole injecting layer and a hole transporting layer.
It is preferable to use a hole injecting material which has a good thin film property and can form a uniform thin film even on an ITO surface having a variation in hydrophilicity. When an element is formed, vapor deposition can be used, so that a thin film of about 1 to 10 nm can be made uniform and pinhole-free. Further, by adjusting the film thickness, the refractive index, and the like, it is possible to prevent a decrease in efficiency by utilizing an interference light effect such as a light emission color, light emission luminance, and light emission spatial distribution.

The hole transporting layer facing the light emitting layer is disclosed in JP-A-63-295695, JP-A-5-234681,
It is preferable to use the compounds disclosed in JP-A-8-48656 and the like.

Although the compounds of the present invention can be used,
The compound of the present invention has a phenylenediamine skeleton, has a very strong donor property, and easily interacts with a luminescent material such that the fluorescence intensity of an exciplex or the like decreases. Therefore, there are adverse effects such as a decrease in luminous efficiency and a decrease in color purity due to broadening of the emission spectrum, which is not preferable. However, when a light emitting material having no interaction is used, it can be used as a hole (hole) transporting material.

The compound of the present invention can be applied to any of a hole injecting layer, a hole transporting layer, a light emitting layer and a hole injecting and transporting layer. It is preferably used for a layer or a hole injection / transport layer. By using the compound of the present invention for the hole injection layer and providing a hole transport layer with little interaction such as TPD, high luminous efficiency can be maintained.

In the present invention, the light emitting layer may contain a fluorescent substance. Examples of such a fluorescent substance include compounds disclosed in JP-A-63-264892, for example, at least one selected from compounds such as quinacridone, rubrene, and styryl dyes. Also, quinoline derivatives such as metal complex dyes having 8-quinolinol or a derivative thereof as a ligand, such as tris (8-quinolinolato) aluminum, tetraphenylbutadiene, anthracene, perylene, coronene, and 12-phthaloperinone derivatives. Furthermore, a phenylanthracene derivative of Japanese Patent Application No. 6-110569, a tetraarylethene derivative of Japanese Patent Application No. 6-114456, and the like can be mentioned.

Further, it is preferable to use in combination with a host substance capable of emitting light by itself, and it is preferable to use it as a dopant.

The host substance is preferably a quinolinolato complex, and more preferably an aluminum complex having 8-quinolinol or a derivative thereof as a ligand. Such an aluminum complex is disclosed in JP-A-63-26469.
No. 2, JP-A-3-255190, JP-A-5-7073
3, JP-A-5-258859, JP-A-6-2158
No. 74 and the like.

Specifically, first, tris (8-quinolinolato) aluminum, bis (8-quinolinolato) magnesium, bis (benzo {f} -8-quinolinolato) zinc, bis (2-methyl-8-quinolinolato) aluminum Oxide, tris (8-quinolinolato) indium,
Tris (5-methyl-8-quinolinolato) aluminum, 8-quinolinolatolithium, tris (5-chloro-
8-quinolinolato) gallium, bis (5-chloro-8-
Quinolinolato) calcium, 5,7-dichloro-8-quinolinolatoaluminum, tris (5,7-dibromo-
8-hydroxyquinolinolato) aluminum, poly [zinc (II) -bis (8-hydroxy-5-quinolinyl) methane], and the like.

In addition to 8-quinolinol or a derivative thereof, an aluminum complex having another ligand may be used, such as bis (2-methyl-
8-quinolinolato) (phenolato) aluminum (III)
, Bis (2-methyl-8-quinolinolato) (ortho-
Cresolato) aluminum (III), bis (2-methyl-
8-quinolinolato) (meth-cresolate) aluminum
(III), bis (2-methyl-8-quinolinolato) (para-cresolato) aluminum (III), bis (2-methyl-8-quinolinolato) (ortho-phenylphenolate)
Aluminum (III), bis (2-methyl-8-quinolinolato) (meth-phenylphenolato) aluminum (II
I), bis (2-methyl-8-quinolinolato) (para-
Phenylphenolato) aluminum (III), bis (2-
Methyl-8-quinolinolato) (2,3-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,6-dimethylphenolato) aluminum (III), bis (2-methyl- 8-quinolinolato)
(3,4-dimethylphenolato) aluminum (III),
Bis (2-methyl-8-quinolinolato) (3,5-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III) ), Bis (2-methyl-8)
-Quinolinolato) (2,6-diphenylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,4,6-triphenylphenolato) aluminum (III), bis (2-methyl- 8-quinolinolato)
(2,3,6-trimethylphenolato) aluminum (I
II), bis (2-methyl-8-quinolinolato) (2,
3,5,6-tetramethylphenolato) aluminum (I
II), bis (2-methyl-8-quinolinolato) (1-naphthrat) aluminum (III), bis (2-methyl-8
-Quinolinolato) (2-naphthrat) aluminum (II
I), bis (2,4-dimethyl-8-quinolinolato)
(Ortho-phenylphenolato) aluminum (III),
Bis (2,4-dimethyl-8-quinolinolato) (para-
Phenylphenolato) aluminum (III), bis (2,
4-dimethyl-8-quinolinolato) (meta-phenylphenolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (3,5-dimethylphenolato) aluminum (III), bis (2 4-dimethyl-8
-Quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III), bis (2-methyl-4-ethyl-8-quinolinolato) (para-cresolato) aluminum (III), bis (2-methyl) -4-methoxy-8-quinolinolato) (para-phenylphenolato) aluminum (III), bis (2-methyl-5-cyano-8-quinolinolato) (ortho-cresolato) aluminum (III),
Bis (2-methyl-6-trifluoromethyl-8-quinolinolato) (2-naphthrat) aluminum (III);

In addition, bis (2-methyl-8-quinolinolato) aluminum (III) -μ-oxo-bis (2-
Methyl-8-quinolinolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) aluminum
(III) -μ-oxo-bis (2,4-dimethyl-8-quinolinolato) aluminum (III), bis (4-ethyl-
2-methyl-8-quinolinolato) aluminum (III)-
μ-oxo-bis (4-ethyl-2-methyl-8-quinolinolato) aluminum (III), bis (2-methyl-4
-Methoxyquinolinolato) aluminum (III) -μ-oxo-bis (2-methyl-4-methoxyquinolinolato)
Aluminum (III), bis (5-cyano-2-methyl-
8-quinolinolato) aluminum (III) -μ-oxo-
Bis (5-cyano-2-methyl-8-quinolinolato) aluminum (III), bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) -μ
-Oxo-bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) and the like.

Other host materials include Japanese Patent Application No.
Also preferred are phenylanthracene derivatives described in -110569 and tetraarylethene derivatives described in Japanese Patent Application No. 6-114456.

The light emitting layer is preferably a mixed layer of at least one or more hole injecting / transporting compounds and at least one or more electron injecting / transporting compounds, in addition to being combined with the above host material. Preferably, the mixed layer contains a dopant. The content of the compound in such a mixed layer is 0.01 to 20 wt%,
More preferably, the content is 0.1 to 15% by weight. When the content of the compound is large (1 wt% or more) and affects carrier transport, the dopant may be used as a mixed layer material. When used in combination with a host substance, the emission wavelength characteristics of the host substance can be changed, light emission shifted to a longer wavelength becomes possible, and the luminous efficiency and stability of the device are improved.

In the mixed layer, a carrier hopping conduction path is formed, so that each carrier moves in a material having a polarity predominant, and carrier injection of the opposite polarity is less likely to occur, so that the organic compound is less likely to be damaged. However, there is an advantage that the device life is extended, but by including the above-mentioned dopant in such a mixed layer, the emission wavelength characteristic of the mixed layer itself can be changed, and the emission wavelength can be shifted to a longer wavelength. And the emission intensity is increased, and the stability of the device is improved.

The hole injecting and transporting compound and the electron injecting and transporting compound used in the mixed layer may be selected from the following compounds for the hole injecting and transporting layer and the compounds for the electron injecting and transporting layer, respectively. Among them, as the electron injecting and transporting compound, it is preferable to use a quinoline derivative, furthermore, a metal complex having 8-quinolinol or a derivative thereof as a ligand, particularly tris (8-quinolinolato) aluminum (AlQ3). It is also preferable to use the above-mentioned phenylanthracene derivatives and tetraarylamine derivatives.

Examples of the compound for the hole injecting and transporting layer include amine derivatives having strong fluorescence, for example, the above-described hole transporting materials such as tetraphenyldiamine derivatives, styrylamine derivatives, and amine derivatives having an aromatic condensed ring. It is preferable to use

The mixing ratio is determined in consideration of the respective carrier mobilities and carrier concentrations. In general, the weight ratio of the compound of the hole injecting / transporting compound to the compound having the electron injecting / transporting function is: 1/99 to 99/1, and even 1
0/90 to 90/10, especially 20/80 to 80/20
Degree).

Further, the thickness of the mixed layer is preferably less than the thickness of the organic compound layer from the thickness corresponding to one molecular layer, more preferably 1 to 85 nm.
Further, the thickness is preferably 5 to 60 nm, particularly preferably 5 to 50 nm.

As a method for forming the mixed layer, co-evaporation in which evaporation is performed from different evaporation sources is preferable. However, when the vapor pressures (evaporation temperatures) are approximately the same or very close, they are mixed in advance in the same evaporation board. Alternatively, it can be deposited. In the mixed layer, it is preferable that the compounds are uniformly mixed, but in some cases, the compounds may exist in an island shape. The light-emitting layer is generally formed to a predetermined thickness by vapor-depositing an organic fluorescent substance or by dispersing and coating the resin in a resin binder.

In the present invention, an electron injection transport layer may be provided. Tris (8-quinolinolato) is used for the electron injection transport layer.
Quinoline derivatives such as organometallic complexes having 8-quinolinol or its derivatives such as aluminum (AlQ3) as ligands, oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro substitution A fluorene derivative or the like can be used. The electron injection / transport layer may also serve as the light emitting layer. In such a case, it is preferable to use tris (8-quinolinolato) aluminum or the like. The electron injecting and transporting layer may be formed by vapor deposition or the like, similarly to the light emitting layer.

When the compound of the present invention is used in a light-emitting layer, a conventional organic E
Various organic compounds used for the L element, for example, JP-A-63-295695, JP-A-2-191694
And various organic compounds described in JP-A-3-792 and the like. For example, for the hole injecting and transporting layer, an aromatic tertiary amine, a hydrazone derivative, a carbazole derivative, a triazole derivative, an imidazole derivative, an indole derivative, and the like can be used.For the electron injecting and transporting layer, aluminum quinolinol and the like can be used. Organic metal complex derivatives, oxadiazole derivatives, pyridine derivatives, pyrimidine derivatives, quinoline derivatives, quinoxaline derivatives, diphenylquinone derivatives, perylene derivatives, fluorene derivatives, and the like can be used.

The thickness of the light emitting layer, the thickness of the hole injecting and transporting layer, and the thickness of the electron injecting and transporting layer are not particularly limited, and vary depending on the design and forming method of the recombination region and the light emitting region. The thickness is preferably about 500 nm, especially about 10 to 200 nm.

The thickness of the hole injecting / transporting layer and the thickness of the electron injecting / transporting layer depend on the design of the recombination / light emitting region, but may be about the same as the thickness of the light emitting layer or about 1/10 to 10 times. .

When the injection layer and the transport layer for electrons or holes are separated from each other, it is preferable that the injection layer has a thickness of 1 nm or more and the transport layer has a thickness of 20 nm or more.

At this time, the upper limits of the thickness of the injection layer and the transport layer are generally about 100 nm for the injection layer and about 500 nm for the transport layer. Such a film thickness is the same when two injection / transport layers are provided.

Further, by controlling the film thickness in consideration of the carrier mobility and carrier density (determined by ionization potential and electron affinity) of the combined light emitting layer, electron injection transport layer and hole injection transport layer, recombination can be achieved. It is possible to freely set the region and the light emitting region, and it becomes possible to design the light emission color, control the light emission luminance and light emission spectrum by the interference effect of both electrodes, and control the spatial distribution of light emission.

For the cathode, it is preferable to use a material having a small work function, for example, Li, Na, K, Mg, Al, Ag, In, or an alloy containing at least one of these.
The cathode preferably has fine crystal grains, and particularly preferably has an amorphous state. The thickness of the cathode is 1
It is preferable to set the thickness to about 0 to 1000 nm.

In addition, Al or a fluorine compound is deposited and sputtered at the end of the formation of the electrode, thereby improving the sealing effect.

In order for the EL element to emit light from the surface, at least one of the electrodes must be transparent or translucent.
Since the material of the cathode is limited as described above, it is preferable to determine the material and the thickness of the anode such that the transmittance of emitted light is preferably 80% or more. In particular,
For example, ITO (tin-doped indium oxide), IZO
(Zinc-doped indium oxide), SnO ₂ , Ni, A
It is preferable to use u, Pt, Pd, polypyrrole, or the like for the anode. Further, the thickness of the anode is preferably about 10 to 500 nm. It is necessary that the driving voltage be low in order to improve the reliability of the element. However, it is preferable that the driving voltage be 10 to 30 Ω / □ (80 to 300 nm in thickness).
O. Actually, the thickness and optical constants of ITO should be designed so that the interference effect due to reflection at the ITO interface can satisfy high light extraction efficiency and high color purity.

In a large device such as a display, wiring of Al or the like may be used because the resistance of ITO increases.

Although there is no particular limitation on the material of the substrate, in the illustrated example, a transparent or translucent material such as glass or resin is used in order to extract emitted light from the substrate side. Further, a color filter film, a fluorescence conversion filter film, a dielectric reflection film may be used for the substrate, or the substrate itself may be colored to control the emission color.

When an opaque material is used for the substrate, the order of lamination shown in FIG. 1 may be reversed.

As the color filter film, a color filter used in a liquid crystal display or the like may be used. However, the characteristics of the color filter are adjusted according to the light emitted from the organic EL, and the extraction efficiency and color purity are adjusted. Should be optimized.

Further, if a color filter capable of cutting off short-wavelength external light which is absorbed by the EL element material or the fluorescence conversion layer is used, the light resistance of the element and the display contrast are improved.

An optical thin film such as a dielectric multilayer film may be used in place of the color filter.

Next, a method for manufacturing the EL device of the present invention will be described.

The cathode and the anode are preferably formed by a vapor phase growth method such as a vapor deposition method or a sputtering method.

For forming the hole injection transport layer, the light emitting layer and the electron injection transport layer, it is preferable to use a vacuum deposition method since a uniform thin film can be formed. When a vacuum deposition method is used, a homogeneous thin film having an amorphous state or a crystal grain size of 0.1 μm or less can be obtained. If the crystal grain size exceeds 0.1 μm, the light emission becomes non-uniform, the driving voltage of the device must be increased, and the charge injection efficiency is significantly reduced.

The conditions for vacuum deposition are not particularly limited.
Degree of vacuum of 0 ^-5 Torr or less, deposition rate is 0.01 to 1 nm
/ Sec. Further, it is preferable to form each layer continuously in a vacuum. If they are formed continuously in a vacuum, impurities can be prevented from adsorbing at the interface between the layers, so that high characteristics can be obtained. Further, the driving voltage of the element can be reduced, and the growth and generation of dark spots can be suppressed.

In the case where a plurality of compounds are contained in one layer when a vacuum evaporation method is used for forming each of these layers, it is preferable to co-deposit each boat containing the compounds by individually controlling the temperature.

The EL device of the present invention is usually used as a DC drive type EL device, but can be driven by AC drive or pulse drive. The applied voltage is usually about 2 to 20V.

[0081]

EXAMPLES Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention.

<Synthesis Example 1> 4,4 ', 4''-tris [-N- (3-
Synthesis of biphenyl) -N-phenylamino] triphenylamine (HIM21: Exemplified Compound No. 1)

In a 200 ml reaction vessel, 28.5 g of 4,4 ′, 4 ″ -triiodotriphenylamine, 57 g of N- (m-biphenyl) -aniline, 4.3 g of activated copper powder, 43 g of potassium carbonate and decalin 50 ml was added, and the mixture was heated at 220 ° C. in an oil bath for 24 hours in an Ar atmosphere. After completion of the reaction, 200 ml of toluene was added, and the mixture was filtered to remove insolubles. The filtrate was washed with water and dried over sodium sulfate. After drying, the solvent was distilled off from the filtrate, the residue was purified four times by a silica gel column (developing solvent: n-hexane / toluene mixed solvent), and recrystallized repeatedly from a hexane / toluene mixed solvent and ethyl acetate. 4,4 ', 4''-Tris (-N
-(3-Biphenyl) -N-phenylamino] triphenylamine (15 g) was obtained.

2 g of this was purified by sublimation to obtain 1.8 g of a transparent glassy solid.

Mass spectrometry: m / e 974 (M ⁺ ), 975 (M + 1 ⁺ ) Infrared absorption spectrum: shown in FIG. ¹ H-NMR spectrum: shown in FIG. Differential scanning calorimetry (DSC): Melting point 218 ° C Glass transition temperature (DSC) 89 ° C

<Synthesis Example 2> 4,4 ', 4''-tris [-N, N-bis (3-biphenyl) amino] triphenylamine (HI
M22: Synthesis of Exemplified Compound No. 19) In a 200 ml reaction vessel, 18.5 g of 4,4 ′, 4 ″ -triiodotriphenylamine and bis (m-biphenyl) amine 47 were added.
g, 2.3 g of activated copper powder, 27 g of potassium carbonate, and 50 ml of decalin.
Heated at 0 ° C. for 48 hours. After the completion of the reaction, add toluene for 20 minutes.
0 ml was added, the mixture was filtered to remove insolubles, and the filtrate was washed with water and dried over sodium sulfate. After drying, the solvent was distilled off from the filtrate, reprecipitated with THF and methanol, and the solid collected by filtration was purified four times by a silica gel column (developing solvent: n-hexane / toluene mixed solvent), and again with THF and methanol. Reprecipitate and vacuum-dry the filtered solid, 4,4 ', 4''
-18 g of tris [-N, N-bis (3-biphenyl) amino] triphenylamine were obtained.

[0087] Of these, 2 g was purified by sublimation to obtain 1.8 g of a transparent glassy solid.

Mass spectrometry: m / e 1202 (M ⁺ ), 1203 (M + 1 ⁺ ) Infrared absorption spectrum: shown in FIG. ¹ H-NMR spectrum: shown in FIG. Differential scanning calorimetry (DSC): Melting point Not observed Glass transition temperature (DSC) 106 ° C

<Synthesis Example 3> 4,4 ′, 4 ″ -tris ｛-N- [N-
Synthesis of phenyl-N-3-tolyl- (aminophenyl)]-N-phenylamino-triphenylamine (HIM23: Exemplified Compound No. 30) N, N`-diphenyl-1,4-phenylenediamine in a 200 ml reaction vessel 17.5 g, 3-g iodotoluene 13 g, activated copper powder 0.3 g, potassium carbonate 50 g and decalin 50
and 200 ml of oil bath temperature in Ar atmosphere
For 24 hours. After the reaction, add 100 ml of toluene
In addition, the mixture was filtered to remove insolubles, and the filtrate was washed with water and dried over sodium sulfate. After drying, the solvent was distilled off from the filtrate, the residue was washed with acetone, and the residue was purified twice by a silica gel column (developing solvent: n-hexane / toluene mixed solvent) to give N, N`-diphenyl-N- 20 g of 3-tolyl-1,4-phenylenediamine were obtained.

Next, 4,4 ′, 4 ″-was placed in a 200 ml reaction vessel.
18.5 g of triiodotriphenylamine and 13.8 g of N, N`-diphenyl-N-3-tolyl-1,4-phenylenediamine
g of activated copper powder, 0.3 g of potassium carbonate, 26 g of potassium carbonate, and 50 ml of decalin.
Heated at 00 ° C. for 48 hours. After the reaction is complete, add
After adding 00 ml, the mixture was filtered to remove insolubles, and the filtrate was washed with water and dried over sodium sulfate. After drying, the solvent was distilled off from the filtrate, and the residue was purified twice using a silica gel column (developing solvent: n-hexane / toluene mixed solvent) to give 4,4 ', 4''
-Tris ｛-N- [N-phenyl-N-3-tolyl- (aminophenyl)]-Nphenylamino｝ triphenylamine 4.
0 g was obtained.

2 g of this was purified by sublimation to obtain 1.8 g of a transparent glassy solid.

Mass spectrometry: m / e 1289 (M ⁺ ), 1290 (M + 1 ⁺ ) Infrared absorption spectrum: shown in FIG. ¹ H-NMR spectrum: shown in FIG. ¹³ C-NMR spectrum: shown in FIG. Differential scanning calorimetry (DSC): melting point not observed, glass transition point 111 ° C

<Synthesis Example 4> 4,4 ′, 4 ″ -tris ｛-N- [N-
Synthesis of phenyl-N-4-tolyl- (aminophenyl)]-N-phenylamino-triphenylamine (HIM24: Exemplified Compound No. 29) The synthesis was performed in the same manner as in Synthesis Example 1. However, 4-iodotoluene was used instead of 3-iodotoluene.

Mass spectrometry: m / e 1289 (M ⁺ ), 1290 (M + 1 ⁺ ) Infrared absorption spectrum: shown in FIG. ¹ H-NMR spectrum: shown in FIG. ¹³ C-NMR spectrum: shown in FIG. Differential scanning calorimetry (DSC): Melting point not observed, glass transition point 118 ° C

Example 1 A glass substrate having an ITO transparent electrode (anode) having a thickness of 100 nm was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, pulled up from boiling ethanol, dried, and exposed to UV ozone. After the cleaning, the substrate was fixed to a substrate holder of a vapor deposition apparatus, and the pressure was reduced to 1 × 10 ⁻⁶ Torr.

Next, the compound 4,4 ′, 4 ″ -tris of the present invention
(-N- (3-biphenyl) -N-phenylamino) triphenylamine (HIM21: Exemplified Compound No. 1) was deposited at a deposition rate of 2 nm.
/ Sec to form a hole injection layer with a thickness of 50 nm.

N, N, N`, N`-tetrakis (-m-biphenyl) benzidine (TPD-105) having the following structure was
Evaporation was performed at a deposition rate of 2 nm / sec to a thickness of 20 nm to form a hole transport layer.

[0098]

Embedded image

Next, while maintaining the reduced pressure state, a tris (8-
(Quinolinolato) aluminum (AlQ3) was deposited at a deposition rate of 0.2 nm / sec to a thickness of 50 nm.

[0100]

Embedded image

Further, while maintaining the reduced pressure state, the MgAg
(Weight ratio 10: 1) at a deposition rate of 0.2 nm / sec.
The cathode is formed by vapor deposition to a thickness of
0 nm was deposited to obtain an EL device.

[0102] When a current flows by applying a voltage to the EL element, 23800cd / m ² at 14V · 800mA / cm ²
Green (emission maximum wavelength λmax = 520 nm, chromaticity coordinate x =
(0.31y = 0.57) was confirmed, and the luminescence was stable for 10,000 hours or more in a dry argon atmosphere. There was no appearance and growth of partial non-light-emitting portions. Luminance half-life is 5 with constant current drive of 10 mA / cm ²
00 hr (Initial luminance 380 cd / m ² Drive voltage rise 2.5
V).

Further, the device manufactured in the same manner was heated at 85 ° C.
When left in a high-temperature bath, no unevenness was observed on the light emitting surface even after 500 hours. No dark spots of 0.1 mm or more were generated or grown.

Example 2 An element was manufactured in the same manner as in Synthesis Example 1. However, HIM22 (exemplified compound No. 19) was used instead of HIM21 (exemplified compound No. 1).

[0105] When a current flows by applying a voltage to the EL element, 20480cd / m ² at 14V · 753mA / cm ²
Green (emission maximum wavelength λmax = 520 nm, chromaticity coordinate x =
(0.31y = 0.56) was confirmed, and this light emission was stable for 10,000 hours or more in a dry nitrogen atmosphere.
There was no appearance and growth of partial non-light-emitting portions. The half life of the luminance is 500 hours with a constant current drive of 10 mA / cm ^2.
(393 cd / m ² drive voltage rise 2.0 V), the first time.

Further, the device manufactured in the same manner was heated at 85 ° C.
When left in a high-temperature bath, no unevenness was observed on the light emitting surface even after 500 hours. No dark spots of 0.1 mm or more were generated or grown.

Example 3 An element was produced in the same manner as in Synthesis Example 1. However, HIM23 (Exemplary Compound No. 30) was used instead of HIM21 (Exemplary Compound No. 1).

[0108] When a current flows by applying a voltage to the EL element, 19500cd / m ² at 13V · 553mA / cm ²
Green (maximum emission wavelength λmax = 515 nm, chromaticity coordinate x =
0.3 y = 0.57) was confirmed, and this light emission was stable for 10,000 hours or more in a dry nitrogen atmosphere.
There was no appearance and growth of partial non-light-emitting portions. The half life of the luminance is 500 hours with a constant current drive of 10 mA / cm ^2.
(340 cd / m ² drive voltage rise 2.0V),

Further, the device manufactured in the same manner was heated at 85 ° C.
When left in a high-temperature bath, no unevenness was observed on the light emitting surface even after 500 hours. No dark spots of 0.1 mm or more were generated or grown.

<Example 4> An element was produced in the same manner as in Synthesis Example 1. However, HIM24 (Exemplary Compound No. 29) was used instead of HIM21 (Exemplary Compound No. 1).

[0111] When a current flows by applying a voltage to the EL element, 21700cd / m ² at 14V · 753mA / cm ²
Green color (emission maximum wavelength λmax = 535 nm, chromaticity coordinate x =
(0.32y = 0.56) was confirmed, and the luminescence was stable in a dry nitrogen atmosphere for 10,000 hours or more.
There was no appearance and growth of partial non-light-emitting portions. The half life of the luminance is 500 hours with a constant current drive of 10 mA / cm ^2.
(388 cd / m ² drive voltage rise 2.0 V),

Further, the device manufactured in the same manner was heated at 85 ° C.
When left in a high-temperature bath, no unevenness was observed on the light emitting surface even after 500 hours. No dark spots of 0.1 mm or more were generated or grown.

<Example 5> An element was manufactured in the same manner as in Example 1. However, the interface between the hole transport layer (TPD105) and the electron injection / transport / light-emitting layer (AlQ3) was co-evaporated to 20 nm.
They were mixed (mixing ratio 1: 1).

When a voltage was applied to this EL element to flow a current, the EL element was 21400 cd / m ² at 980 mA / cm ² at 16 V.
Green (emission maximum wavelength λmax = 525 nm, chromaticity coordinate x =
0.3 y = 0.56) was confirmed, and the luminescence was stable for 10,000 hours or more in a dry nitrogen atmosphere. There was no appearance and growth of partial non-light-emitting portions.
The half-life of luminance is 30, with a constant current drive of 10 mA / cm ² .
00 hr (330 cd / m ² drive voltage rise 1.5 V).

Further, the device fabricated in the same manner was heated at 85 ° C.
, No unevenness was observed on the light emitting surface even after 500 hours. No dark spots of 0.1 mm or more were generated or grown.

<Comparative Example 1> An element was produced in the same manner as in Synthesis Example 1. However, instead of HIM21, 4,4 ′, 4 ″ -tris (-N- (3-methylphenyl) -N-phenylamino) triphenylamine (MTDATA) was used.

[0117] When a current flows by applying a voltage to the EL element, 21700cd / m ² at 13V · 518mA / cm ²
Green (emission maximum wavelength λmax = 520 nm, chromaticity coordinate x =
(0.32y = 0.56) was confirmed. The half-life of the luminance was 500 hr (initial luminance: 381 cd / m ² , driving voltage rise: ^2.5 V) by driving at a constant current of 10 mA / cm ² .

Further, the device manufactured in the same manner was heated at 85 ° C.
When left in a high-temperature bath, the light emitting surface became uneven in 10 hours. The generation and growth of dark spots was also remarkable.

<Comparative Example 2> An element was produced in the same manner as in Example 1. However, instead of HIM21, copper phthalocyaninyl was used in a thickness of 10 nm. When a voltage was applied to this EL element to cause a current to flow, 14 V · 532 mA /
Green of 21000 cd / m ^{2 in} cm ² (maximum emission wavelength λmax =
Light emission of 528 nm and chromaticity coordinates x = 0.32y = 0.57) was confirmed. The half-life of luminance is 10 mA / cm ² constant current drive (initial luminance 381 cd / m ² , drive voltage rise 3.0
V), it was confirmed up to 200 hours, but the dark spots grew so strongly that accurate measurement of luminance was not possible.

Further, the device manufactured in the same manner was heated at 85 ° C.
When left in a high-temperature bath, the light emitting surface became uneven in 100 hours. The generation and growth of dark spots was also remarkable.

[0121]

As described above, the organic E using the compound of the present invention
For the L element, a driving voltage rise and a decrease in luminance during driving of the element,
Suppress the leakage of current, the appearance and growth of partial non-light emitting parts,
A decrease in luminance is small, high luminance, high reliability such as high heat resistance, an optimum work function for the positive electrode and the organic material to be combined can be provided, and an element with high continuous emission reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a configuration example of an organic EL device of the present invention.

FIG. 2 is an infrared absorption spectrum diagram of Synthesis Example 1.

FIG. 3 is a ¹ H-NMR spectrum diagram of Synthesis Example 1.

FIG. 4 is an infrared absorption spectrum diagram of Synthesis Example 2.

FIG. 5 is a ¹ H-NMR spectrum diagram of Synthesis Example 2.

FIG. 6 is an infrared absorption spectrum diagram of Synthesis Example 3.

FIG. 7 is a ¹ H-NMR spectrum diagram of Synthesis Example 3.

FIG. 8 is a ¹³ C-NMR spectrum diagram of Synthesis Example 3.

9 is an infrared absorption spectrum diagram of Synthesis Example 4. FIG.

FIG. 10 is a ¹ H-NMR spectrum diagram of Synthesis Example 4.

11 is a ¹³ C-NMR spectrum diagram of Synthesis Example 4. FIG.

[Explanation of symbols]

 2 Substrate 3 Anode 4 Hole injection / transport layer 5 Light emitting layer 6 Electron injection / transport layer 7 Cathode 8 Color filter 9 Fluorescence conversion filter 10 Sealing layer 11 Cover

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Junji Aoya 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation

Claims (4)

[Claims] 1. An organic EL device having at least one or more organic compound layers, wherein at least one of the organic material layers contains a compound represented by the following formula (I). Embedded image (In the formula (I), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are
Each represents a hydrogen atom, an alkyl group, an alkoxy group, a 3-phenyl group, a phenoxy group, an arylamino group, or a diarylamino group. Where R ₁ , R ₂ , R ₃ ,
At least one of R _4, R ₅ and R ₆ is 3-phenyl group, an arylamino group or a diarylamino group. ) 2. An organic EL device having at least a hole injecting and transporting layer and a light emitting layer as the organic compound layer, wherein the hole injecting and transporting layer contains the compound of claim 1. 3. An organic EL comprising a hole injection layer and a light emitting layer as the organic compound layer, wherein the hole injection layer contains the compound of claim 1.
element. 4. The organic EL device according to claim 1, wherein the light emitting layer contains a hole injecting and transporting compound and an electron injecting and transporting compound.