JPH11260559A - Organic thin film el element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic thin film EL(electroluminescent) element not only capable of self-emitting light with excellent visibility at low driving voltage and at high light emitting efficiency but also having long life stably usable for a long period. SOLUTION: A positive hole transporting layer of this organic thin film EL element are made of at least two types of positive hole transporting materials and contains a positive hole transporting material having asymmetric molecular structure or contains at least a main positive hole transporting material and another positive hole transporting material with a molecular weight 2/3 times as low as that of the main positive hole transporting material or lower. On the other hand, the electron injection electrode has a layered structure constituted of layers of mainly aluminum and layers of mainly chromium or the electron injection electrode is coated with a film with 1 μm or thicker produced by plasma polymerization of octafluorocyclobutane.

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 a method of manufacturing the same, for example, a self-luminous device that can be used as a light source for various purposes such as a flat-type self-luminous display device, communication, lighting and other uses. Of the device.

[0002]

2. Description of the Related Art In recent years, LCD panels have been widely used as flat-type display devices, but they still have drawbacks such as slow response speed and narrow viewing angle, and many new systems in which these have been improved have been improved. However, there are problems such as insufficient characteristics and an increase in cost as a panel. Under such circumstances, self-emission, excellent visibility, high response speed, and expectations for organic EL devices as new light-emitting devices that can be expected for a wide range of applications have been gathered.

In an organic EL device, electrons are transferred from an electrode to an organic material layer.
Light is emitted by injecting holes and recombining the holes. Many studies have been made since ancient times, but the luminous efficiency is generally low and is far from practically applicable to light emitting devices.

In such a situation, a device proposed by Tang et al. In 1987 (“Apply Physics”)
Letter 51, 1987, p. 913 "(CWTa
ngand SAVanslyke: Appl. Phys. Let
t. 51 (1987) 913. )) Is an element having a transparent hole injection electrode, an organic thin film layer, and an electron injection electrode on a transparent substrate, wherein the organic thin film layer has a hole transport layer and a light emitting layer (electron transport layer) laminated. And MgAg as an alloy of a metal having a low work function and a low electron injection barrier as an electron injection electrode and a metal having a relatively large work function and being stable.
Was used.

[0005] By using such an electron injection electrode, it is possible to inject electrons with high efficiency and relatively stability, and to obtain high efficiency near the interface between the hole transport layer and the light emitting layer (electron transport layer). Light emission can be obtained. Tang et al. Have such a configuration, and at a low voltage of 10 V or less,
High luminance of d / m ² or more and high efficiency of 1.5 lm / W or more are realized.

[0006] The report of Tang et al. Has triggered active studies even today. The following is a brief description of the organic EL devices that are currently generally studied. In general, an organic EL device is formed by laminating a hole injection electrode, an organic thin film layer, and an electron injection electrode on a transparent substrate in this order, and the organic thin film layer includes a hole transport layer and a light emitting layer (electron transport layer). In many cases, a plurality of laminated films are used. In this way, by making each layer play a role by separating the function, an appropriate material can be selected for each layer, and the characteristics of the element are also improved.

As a transparent substrate, generally, Corning 173 is used.
Glass substrates such as 7 are widely used. Sheet thickness is 0.7
About 1.1 mm is easy to handle from the viewpoint of strength and weight.

As the hole injection electrode, a transparent electrode such as an ITO sputtered film, an electron beam evaporated film, or an ion plating film is used. The film thickness is determined from the required sheet resistance value and the visible light transmittance. However, since the driving current density of the organic EL element is relatively high, the organic EL element may be used at a thickness of 100 nm or more to reduce the sheet resistance. Many.

Various configurations of the organic thin film layer have been studied. A hole transport layer formed by vacuum deposition of a hole transport material such as a triphenyldiamine derivative into a film having a thickness of several tens nm is provided.
In many cases, a layer in which a light emitting material (electron transporting material) such as tris (8-hydroxyquinoline) aluminum is formed to a thickness of several tens nm by vacuum deposition is laminated.

The electron injection electrode is made of Mg proposed by Tang et al.
An alloy of a metal having a low work function and a low electron injection barrier, such as an Ag alloy or an AlLi alloy, and a metal having a relatively large work function and being stable are often used.

[0011]

As described above, a stacked element structure having a function separation according to the proposal of Tang et al. Is used, and a metal such as MgAg having a low work function and a low electron injection barrier is used as an electron injection electrode. By using an alloy with a metal having a large and stable function, a light-emitting element having practical characteristics has been obtained, but a light-emitting element having sufficient performance has not been obtained in terms of its stability or life, In general, even when the light-emitting element is driven at a constant current, there is a problem that the light emission luminance gradually decreases and a non-light-emitting portion called a black point gradually grows to cause a problem on an image.

[0012]

Means for Solving the Problems We have conducted intensive studies to solve this problem, and as a result, have found that the essence of these problems is largely divided into two phenomena. That is, the first cause is deterioration due to crystallization or aggregation of the hole transport layer, and the second cause is oxidation of the electron injection electrode,
Deterioration due to corrosion and the like. The term "alteration" as used herein refers to a change in form, delamination, a change in electrical characteristics such as ionization potential and hole transportability.

Therefore, as a means for suppressing the first cause, we examined the stability of various hole transporting materials mainly in a high-temperature and high-humidity environment, and found that a hole transporting layer composed of specific relatively large and rigid molecules was used. In the present invention, it was found that by mixing a specific other hole transport molecule having a small molecular weight or a specific other hole transport molecule having an asymmetric molecular structure, the change with time can be significantly suppressed. Was completed.

Further, as a means for suppressing the first and second causes, we examined various electrode materials, electrode configurations, and protective layers. As a result, it was found that a Cr layer was laminated as an electrode, and a specific protective layer was formed. It has been found that the use of the compound can greatly suppress the change over time of the element characteristics, and can substantially improve the life of the element, thereby completing the present invention.

Specifically, the organic thin-film EL device according to the first aspect of the present invention comprises an electron injection electrode and a hole injection electrode on a transparent substrate, and at least a space between the electron injection electrode and the hole injection electrode. An organic thin film EL device having a hole transport layer provided therein, wherein the hole transport layer is made of at least two types of hole transport materials and contains a hole transport material having an asymmetric molecular structure. EL element.

Further, in the invention of claim 2 of the present application, the hole transporting layer of claim 1 mainly comprises a compound represented by the general formula (1)
2, R3, R4 and R5 may be the same or different,
R1, R2, and R3 represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group, and R4 and R5 represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom. The organic thin film EL element to be used.

According to a third aspect of the present invention, in the first aspect, the hole transport layer is mainly composed of N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine. The organic thin film EL element to be used.

The invention according to claim 4 of the present application is directed to the hole transport layer according to claim 1 or 2 or 3, wherein the content of the hole transport material having an asymmetric molecular structure is 3% by weight.
This is an organic thin film EL element of 0% or less.

An organic thin-film EL device according to a fifth aspect of the present invention provides an electron-injection electrode and a hole-injection electrode on a transparent substrate, and holes provided at least between the electron-injection electrode and the hole-injection electrode. An organic thin film EL device having a transport layer, wherein the hole transport layer is made of at least two types of hole transport materials, and at least the main hole transport material and 2 /
Organic thin film E containing a hole transport material having a molecular weight of 3 or less
L element.

According to the invention of claim 6 of the present application, the main hole transporting material of the hole transporting layer of claim 5 is represented by the following general formula (1).
(Wherein R1, R2, R3, R4, and R5 may be the same or different; R1, R2, and R3 represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group; R4 and R5 represent a hydrogen atom or a lower alkyl group; , A lower alkoxy group, or a chlorine atom).
It is an element.

According to a seventh aspect of the present invention, in the fifth aspect, the hole transport layer is mainly composed of N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine. The organic thin film EL element to be used.

The invention according to claim 8 of the present application is directed to the hole transporting layer according to claim 5 or 6 or 7, wherein the hole transporting material having a molecular weight of 2/3 or less of the molecular weight of the main hole transporting material is used. Organic thin film E whose content is 30% or less by weight
This is an L element.

According to a ninth aspect of the present invention, there is provided an organic thin film EL device, comprising: an electron injection electrode and a hole injection electrode on a transparent substrate; and a hole provided at least between the electron injection electrode and the hole injection electrode. And the hole transport layer of the organic thin film EL device having a transport layer.
2, R3, R4 and R5 may be the same or different,
R1, R2, and R3 represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group; R4, R5 represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom); (Formula 2) (wherein R1, R
2, R3 and R4 may be the same or different and represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group)
And an organic thin film EL device containing a guest compound represented by the formula:

The invention of claim 10 of the present application is the invention of claim 9
Is N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine, and the guest compound is 4-N, N'-bis (p-methylphenyl) amino-α -An organic thin film EL device that is phenylstilbene.

The invention of claim 11 of the present application is directed to claim 9
Wherein the proportion of the host compound in the hole transport layer is 70% or more by weight and the proportion of the guest compound is 30% or less by weight.

An organic thin-film EL device according to a twelfth aspect of the present invention provides an electron-injection electrode and a hole-injection electrode on a transparent substrate, and holes provided at least between the electron-injection electrode and the hole-injection electrode. And the hole transport layer of the organic thin film EL device having a transport layer.
2, R3, R4 and R5 may be the same or different,
R1, R2, and R3 represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group; R4, R5 represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom); (Formula 3) (wherein R1, R
2, R3 and R4 may be the same or different and represent a hydrogen atom, a chlorine atom, a methyl group, a methoxy group, a dimethylamino group, a diethylamino group, a diphenylamino group, or a dibenzylamino group) An organic thin film EL device containing a compound.

The invention of claim 13 of the present application is directed to claim 1
2, the host compound is N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine, and the guest compound is 1,1-bis (p-diethylaminophenyl) -4,4- This is an organic thin film EL device of diphenyl-1,3-butadiene.

The invention of claim 14 of the present application is the invention of claim 1
2 is an organic thin film EL device in which the proportion of the host compound in the hole transport layer is at least 70% by weight and the proportion of the guest compound is at most 30% by weight.

An organic thin-film EL device according to a fifteenth aspect of the present invention provides an electron-injection electrode and a hole-injection electrode on a transparent substrate, and holes provided at least between the electron-injection electrode and the hole-injection electrode. And the hole transport layer of the organic thin film EL device having a transport layer.
2 may be the same or different and represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a substituted or unsubstituted aryl group, and R3 represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom) And a host compound represented by the general formula (Chemical Formula 2) (wherein R1, R2, R3, R
4 may be the same or different, and represents a hydrogen atom, a lower alkyl group, or a lower alkoxy group).

[0030] The invention of claim 16 of the present application is the invention of claim 1.
5 is N, N'-diphenyl-N, N'-
Bis (3-methylphenyl) -1,1′-biphenyl-
This is an organic thin film EL device in which 4,4′-diamine and a guest compound are 4-N, N′-bis (p-methylphenyl) amino-α-phenylstilbene.

Further, the invention of claim 17 of the present application is the invention of claim 1
5 is an organic thin-film EL device in which the proportion of the host compound in the hole transport layer is 70% or more by weight and the proportion of the guest compound is 30% or less by weight.

The organic thin-film EL device according to the eighteenth aspect of the present invention provides an electron injection electrode and a hole injection electrode on a transparent substrate, and at least a hole provided between the electron injection electrode and the hole injection electrode. And the hole transport layer of the organic thin film EL device having a transport layer.
2 may be the same or different and represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a substituted or unsubstituted aryl group, and R3 represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom) And a host compound represented by the general formula (Chemical Formula 3) (wherein R1, R2, R3, R
4 may be the same or different and represents a hydrogen atom, a chlorine atom, a methyl group, a methoxy group, a dimethylamino group, a diethylamino group, a diphenylamino group, or a dibenzylamino group). Organic thin-film EL device.

Further, the invention of claim 19 of the present application is the invention of claim 1
8 is N, N'-diphenyl-N, N'-
Bis (3-methylphenyl) -1,1′-biphenyl-
4,4′-diamine, the guest compound is 1,1-bis (p
-Diethylaminophenyl) -4,4-diphenyl-
This is an organic thin film EL device of 1,3-butadiene.

[0034] The invention of claim 20 of the present application is the invention of claim 1.
8 is an organic thin film EL device in which the proportion of the host compound in the hole transport layer is 70% or more by weight and the proportion of the guest compound is 30% or less by weight.

An organic thin-film EL device according to a twenty-first aspect of the present invention provides an electron-injection electrode and a hole-injection electrode on a transparent substrate, and at least a hole provided between the electron-injection electrode and the hole-injection electrode. And the hole transport layer of the organic thin film EL device having a transport layer.
2, R3, R4 and R5 may be the same or different,
R1, R2, and R3 represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group; R4, R5 represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom); (Formula 4) (wherein R1, R
2 may be the same or different and represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a substituted or unsubstituted aryl group, and R3 represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom) And an organic thin film EL device containing a guest compound represented by the formula:

The invention of claim 22 of the present application is the invention of claim 2
1 is N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine, and the guest compound is N, N'-diphenyl-N,
This is an organic thin-film EL device which is N'-bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine.

The invention of claim 23 of the present application is the invention of claim 2
1 is an organic thin film EL device in which the proportion of the host compound in the hole transport layer is 70% or more by weight and the proportion of the guest compound is 30% or less by weight.

An organic thin-film EL device according to a twenty-fourth aspect of the present invention is the organic thin-film EL device according to claim 24, wherein at least a hole injection electrode, an organic thin-film layer, and an electron injection electrode are laminated on a transparent substrate. The electrode is an organic thin film EL device having a laminated structure of a layer mainly composed of aluminum and a layer mainly composed of chromium.

An organic thin-film EL device according to a twenty-fifth aspect of the present invention is the organic thin-film EL device according to claim 25, wherein at least a hole injection electrode, an organic thin-film layer, and an electron injection electrode are laminated on a transparent substrate. This is an organic thin film EL device having a lead difluoride layer on an electrode.

An organic thin-film EL device according to a twenty-sixth aspect of the present invention is the organic thin-film EL device, wherein at least a hole injection electrode, an organic thin-film layer, and an electron injection electrode are laminated on a transparent substrate. This is an organic thin film EL device having a plasma polymerized film of octafluorocyclobutane on an electrode with a thickness of 1 μm or more.

An organic thin-film EL device according to a twenty-seventh aspect of the present invention is the organic thin-film EL device comprising a transparent substrate and at least a hole injection electrode, an organic thin-film layer, and an electron injection electrode laminated on each other. An organic thin film EL device having an octafluorocyclobutane plasma polymerized film on an electrode and a protective layer formed on the plasma polymerized film.

The method of manufacturing an organic thin film EL device according to the invention of claim 28 of the present application is a method of manufacturing an organic thin film EL device having at least a hole injection electrode, an organic thin film layer, and an electron injection electrode laminated on a transparent substrate. A method for producing an organic thin-film EL device, comprising: forming a plasma polymerized film of octafluorocyclobutane on the electron injection electrode; and forming a protective layer on the plasma polymerized film.

An organic thin-film EL device according to a twenty-ninth aspect of the present invention is the organic thin-film EL device according to claim 29, wherein at least a hole injection electrode, an organic thin-film layer, and an electron injection electrode are laminated on a transparent substrate. An organic thin-film EL device having a structure in which aluminum is formed in an island shape and the electron injection electrode is formed thereon.

The method of manufacturing an organic thin-film EL device according to the invention of claim 30 of the present application is a method of manufacturing an organic thin-film EL device in which at least a hole injection electrode, an organic thin-film layer, and an electron injection electrode are laminated on a transparent substrate. Forming an electron injection electrode on the organic thin film by a method, wherein the electron injection electrode is formed after the step of forming aluminum in an island shape on the organic thin film. .

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an organic thin film EL device according to an embodiment of the present invention and a method for manufacturing the same will be described.

The organic thin-film EL device of the present invention comprises an electron injection electrode and a hole injection electrode on a transparent substrate, and at least a hole transport layer provided between the electron injection electrode and the hole injection electrode. However, as is generally known, various laminated structures such as a light emitting layer, an electron transport layer, and a hole injection layer can be used.

The transparent substrate in the present invention may be any as long as it can support the organic thin film EL element of the present invention, and a common glass substrate such as Corning 1737 glass is often used. Can also be used. Generally, one of the electron injection electrode and the hole injection electrode needs to be transparent, and a transparent electrode is provided on a transparent substrate to emit light to the outside. Usually, a transparent ITO (indium tin oxide) film is often used for the hole injection electrode, and the electron injection electrode is made of Ta.
In many cases, an alloy of a metal having a low work function and a low electron injection barrier and a metal having a relatively large work function and being stable, such as an MgAg alloy or an AlLi alloy proposed by ng et al.

The ITO film is formed by a film forming method such as sputtering, electron beam evaporation, or ion plating for the purpose of improving the transparency or reducing the resistivity, and various methods for controlling the resistivity and the shape. Post-processing is often performed. The film thickness is determined from the required sheet resistance value and the visible light transmittance. However, since the driving current density of the organic EL element is relatively high, the organic EL element must be used at a thickness of 100 nm or more to reduce the sheet resistance. There are many.

For the hole injection electrode of the present invention, in addition to these normal ITO films, a transparent conductive paint coating film in which conductive powder is dispersed and other electrodes can be used. The electron injection electrode of the present invention has the above-mentioned MgA
g, AlLi and other alloys of a metal having a low work function and a low electron injection barrier and a metal having a relatively high work function and a stable metal. In addition, after forming a thin Li film first, a relatively thick Al film is formed. Laminated electrode, LiF film and Al ₂ O ₃
It is possible to use a laminated electrode in which an Al film is formed relatively thick after forming a thin film, or various other electrode configurations.

In the invention as set forth in claims 1 to 23 of the present application, the main part is in the hole transport layer, and the transparent substrate, the electron injection electrode, and the hole injection electrode described above are all widely used. Can be done. The light emitting layer is a layer in which a light emitting material (electron transporting material) such as tris (8-hydroxyquinoline) aluminum is formed to a thickness of several tens of nanometers by vacuum evaporation, and the transparent substrate / hole injection electrode / hole transporting layer / Emitting layer /
A configuration in which the layers are stacked like an electron injection electrode, a configuration in which an appropriate luminescent material is doped in a hole transport layer or an electron transport layer, or the like can be used.

In these inventions, a hole transporting material having an asymmetric molecular structure refers to a hole transporting material whose molecular structure is not symmetrical left and right or up and down, for example, 4-N, N '.
Styrylamine derivatives such as -bis (p-methylphenyl) amino-α-phenylstilbene, or 1,1
A hole transport material such as -bis (p-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene, which has a symmetric skeletal molecule but is substantially asymmetric due to the introduction of a relatively large substituent. Can be mentioned. The main hole transporting material in the hole transporting layer refers to the material having the highest content by weight of the hole transporting materials contained in the hole transporting layer. In addition, among the materials that also include the host compound,
The guest compound refers to the material with the highest content by weight, and the guest compound refers to the other material.

In the invention according to claims 24, 29 and 30, the main part is in the electron injection electrode, and the transparent substrate, the hole injection electrode, the hole transport layer, the light emitting layer and the like are all general-purpose ones. Can be used widely. The transparent substrate may be a glass substrate or various resin films described above, and the hole injection electrode may be a general-purpose ITO film. The hole transporting layer may be a layer formed by depositing a hole transporting material such as a triphenyldiamine derivative to a thickness of several tens of nanometers by vacuum deposition. The hole transporting layer according to any one of claims 1 to 23 of the present invention can be used. A transport layer can also be used. The light emitting layer is Tris (8-
A structure in which a luminescent material (electron transporting material) such as (hydroxyquinoline) aluminum is formed to a thickness of several tens of nanometers by vacuum evaporation and laminated as a transparent substrate / hole injection electrode / hole transporting layer / light emitting layer. Alternatively, a configuration in which an appropriate luminescent material is doped in the hole transport layer or the electron transport layer, or the like can be used.

In the invention according to claim 24 of the present application, the laminated structure of a layer mainly composed of aluminum and a layer mainly composed of chromium means that a layer mainly composed of chromium is formed on a normal alloy electron injection electrode of AlLi or the like. Refers to a configuration having a substantially corrosion-resistant layer of chromium. Between each of these layers, or at the lower or upper part, if necessary, an adhesive layer or other layers may be provided for other purposes. The thickness of the layer mainly made of aluminum may be a thickness that can realize the necessary wiring resistance, and is often used in the range of several tens nm to several hundreds nm. The thickness of the layer mainly composed of chromium is such that the lower layer can be sufficiently shielded and protected from oxygen, moisture and other reactive substances due to the substantially high corrosion resistance of the chromium layer. The thickness is preferably at least several nm or more, preferably several tens nm or more. As a film forming method, vacuum evaporation, sputtering, or other ordinary methods can be used.

In the invention as set forth in claims 29 and 30 of the present application, forming aluminum in an island shape on the organic thin film means that electron injection is performed on the organic thin film such as the above-described hole transport layer, light emitting layer and electron transport layer. Before forming the electrode, it refers to forming aluminum in an island shape.Specifically, a normal thin film forming method such as evaporation and sputtering can be used, but before aluminum covers the organic thin film in a film shape. , Indicating that the formation is performed up to the stage where the island is still formed. Also in the present invention, a general-purpose electron injection electrode such as AlLi can be widely used as the electron injection electrode to be formed later as described above. If the coverage at the time of forming aluminum in an island shape is too high, the function as an electron injection electrode is substantially performed by aluminum, so that the driving voltage is high and the characteristics are impaired. On the other hand, if it is too low, sufficient effects cannot be obtained from the viewpoint of life, and the effects of the present invention cannot be obtained. Effective coverage in the present invention is 10% or more and 90% in area ratio.
Or less, preferably 20% or more and 80% or less.

In the invention according to the twenty-fifth to twenty-eighth aspects of the present invention, the main part is a protective layer formed on the electron injection electrode, and the transparent substrate, the hole injection electrode, the hole transport layer, the light emitting layer,
As the organic thin film layer such as the electron transport layer and the electron injection electrode, general-purpose materials can be widely used. The transparent substrate may be a glass substrate or various resin films described above, and the hole injection electrode may be a general-purpose ITO film. The hole transporting layer may be a layer formed by depositing a hole transporting material such as a triphenyldiamine derivative to a thickness of several tens of nanometers by vacuum deposition. The hole transporting layer according to any one of claims 1 to 23 of the present invention can be used. A transport layer can also be used.

The light emitting layer is a layer formed by forming a light emitting material (electron transporting material) such as tris (8-hydroxyquinoline) aluminum to a thickness of several tens of nm by vacuum deposition. The transparent substrate / hole injection electrode / hole transporting layer is used. A layered structure such as a layer / light-emitting layer, a structure in which an appropriate light-emitting material is doped in a hole transport layer or an electron transport layer, or the like can be used.

The electron injection electrode is made of MgAg alloy or AlL
A wide range of commonly used materials such as an alloy of a metal having a low work function and a low electron injection barrier, such as an i-alloy, and a metal having a relatively large work function and being stable can be used. The protective layer formed on the electron injecting electrode does not need to be formed immediately above and in contact with the electron injecting electrode. If necessary, an adhesive layer or another layer can be provided for other purposes. The role of the protective layer in the present invention is to shield and protect the organic thin film layer carried between the hole injection electrode and the electron injection electrode and the electrodes themselves from oxygen, moisture and other reactive substances penetrating from outside the device. And plays a role by having the layer outside the electron injection electrode.

In the invention according to claim 25 of the present application, 2
The lead fluoride layer can be formed by vacuum evaporation or other normal thin film forming method. Specifically, lead difluoride powder obtained as a normal reagent is resistance-heated on a boat, A film deposited by vacuum deposition or the like can be used. 2
The thickness of the lead fluoride layer may be thick enough to be formed without pinholes over the entire surface of the film.
Preferably it is about 100 to 1000 nm.

The plasma polymerized film of octafluorocyclobutane in the invention as set forth in claims 26 to 28 of the present application is obtained by introducing a commercially available octafluorocyclobutane into a vacuum chamber, and performing a normal high-frequency discharge, microwave discharge, direct current discharge under reduced pressure. A polymer film formed on an electron injection electrode by plasma formed by means such as discharge.

An organic thin-film EL element formed at least up to a hole injection electrode / organic thin-film layer / electron injection electrode on a transparent substrate is supported in a vacuum chamber having a usual exhaust device, and octafluorocyclobutane is appropriately charged. Introduced to a pressure, formed plasma by appropriate electrodes and discharge means,
It is sufficient that a polymer film of octafluorocyclobutane can be formed with a film thickness of 1 μm or more. However, since a uniform film can be easily formed over a relatively large area, 13.56 MHz which is industrially used for a capacitively coupled parallel plate electrode is generally used. High frequency power supply or a high frequency power supply of about 50 to 300 kHz is often used.

The pressure may be any pressure at which the plasma can be stably maintained by the connected and supplied electromagnetic field, but is usually 0.01 to 100 Torr, preferably 0.1 to 1 Torr.
It is often used in the range of 0 Torr. The film thickness of the polymer film of octafluorocyclobutane needs to be 1 μm or more, and if the film thickness is less than 1 μm, a sufficient effect of the present invention cannot be obtained. The effect is greater when the film thickness is larger, but a sufficient effect is usually obtained with a film thickness of several μm.

The essential part of the invention according to claim 27 of the present application is that an organic thin film EL element formed at least up to a hole injection electrode / organic thin film layer / electron injection electrode on a transparent substrate and a protective layer. It has a plasma polymerized film of octafluorocyclobutane, and the protective layer formed on the organic thin film layer held between the hole injection electrode and the electron injection electrode and those electrodes themselves from the outside of the device. What is necessary is just to be excellent in the performance of shielding and protecting from invading oxygen, moisture and other reactive substances.

The essential part of the invention according to claim 28 of the present application is that an organic thin film EL element having at least a hole injection electrode / organic thin film layer / electron injection electrode formed on a transparent substrate is
After the step of forming a plasma polymerized film of octafluorocyclobutane, there is a step of forming a protective layer thereon, and the step of forming the protective layer is carried between the hole injection electrode and the electron injection electrode. Any process may be used as long as it is possible to form a protective layer having excellent performance of shielding and protecting the organic thin film layers and their electrodes themselves from oxygen, moisture and other reactive substances penetrating from outside the device.

In the invention according to claims 27 and 28, since the protective layer is formed on the octafluorocyclobutane plasma polymerized film as described above, the lower organic thin film EL element itself is formed in the film forming step. Plasma CVD, light CV without deteriorating the characteristics of
Any film that can be formed by D, sputtering, laser ablation, or other methods can be used. That is, unlike the formation of a protective layer on a normal organic thin-film EL element, the present invention is characterized in that a protective layer having a protection performance truly suitable for an organic thin-film EL element can be formed and used.

For example, among specific amorphous carbon thin films formed from high-energy active species obtained from a specific plasma state, there is an extremely hard, dense, and chemically-defined diamond-like thin film (DLC). Also has a stable thin film,
Suitable for a protective layer of an organic thin film EL device. However, since such a protective layer is formed from a high-energy active species, the characteristics of the underlying organic thin-film EL element itself are deteriorated in the film-forming process, and the protective layer cannot be used. By employing the present invention, an organic thin film EL device having such an excellent protective layer can be obtained.

Next, the present invention will be described in more detail based on specific embodiments. (Example 1) As a substrate having a hole injection electrode formed on a transparent substrate, a commercially available glass substrate with ITO (manufactured by Sanyo Vacuum Co., Ltd., size 100 × 100 mm × t = 0.7 mm, sheet resistance about 14Ω / □) ) And patterned by photolithography so that the emission area becomes 10 × 10 mm due to the overlap with the electron injection electrode.

For the substrate treatment after photolithography, the substrate is immersed in a commercially available resist stripping solution (a mixed solution of dimethyl sulfoxide and n-methyl-2-pyrrolidone) for stripping, rinsed with acetone, and further immersed in fuming nitric acid for 1 minute. Then, the resist was completely removed.

Washing of the ITO surface is performed sufficiently on both sides of the back surface of the substrate, while sufficiently supplying a 0.238% aqueous solution of tetramethylammonium hydroxide.
Mechanical rubbing with a nylon brush was performed.

Thereafter, the substrate was sufficiently rinsed with pure water and spin-dried. Before vapor deposition of the organic thin film EL element, a commercially available plasma reactor (PR41 manufactured by Yamato Scientific Co., Ltd.) was used.
Mold), oxygen flow rate 20 sccm, pressure 0.2 Torr
After performing an oxygen plasma treatment for 1 minute under the conditions of r and a high frequency output of 300 W, the substrate was placed in a vapor deposition tank.

The vacuum evaporation apparatus used was a modified version of a commercially available high vacuum evaporation apparatus (model EBV-6DA, manufactured by Japan Vacuum Engineering Co., Ltd.). The main evacuation device is a turbo molecular pump (TC 1500, manufactured by Osaka Vacuum Co., Ltd.) with an evacuation speed of 1500 l / min, and the ultimate degree of vacuum is about 1 × 10 ^−6.
Torr or less, and all depositions are 2-3 × 10 ⁻⁶ To
Performed in the range of rr. All evaporations were performed by connecting a direct current power supply (PAK10-70A, manufactured by Kikusui Electronics Co., Ltd.) to a tungsten resistance heating evaporation boat.

The ITO thus arranged in the vacuum layer
N, N'-bis (4'-diphenylamino-4-biphenylyl)-as a hole transport layer on a glass substrate
N, N'-diphenylbenzidine (manufactured by Hodogaya Chemical Co., Ltd.) and 4-N, N'-bis (p-methylphenyl)
Amino-α-phenylstilbene,
Co-deposition was performed at a deposition rate of m / s and 0.01 nm / s to form a film with a thickness of about 80 nm. 4-N, N'-bis (p-
Methylphenyl) amino-α-phenylstilbene is
It was synthesized as follows.

Diphenylbromomethane dissolved in dry toluene is added dropwise over a period of 3 hours while 80 ml of ethyl phosphate is kept at 140 to 145 ° C. while drying and stirring, and the generated bromoethane is distilled off.

It takes another 3 hours after dropping to raise the liquid temperature to 180.
C., the toluene was distilled off, and 88.4 g of 1,4 was distilled off under reduced pressure (nitrogen atmosphere: 1 mmHg, 140-165 ° C.).
Diethyl 1-diphenylmethylphosphonate was obtained. 26.0 g of diethyl 1,1-diphenylmethylphosphonate, 23.4 g of 4-N, N'-diphenylaminobenzaldehyde and 160 ml of dry DMF thus obtained were dried and stirred at a liquid temperature of 21 to 23 [deg.] C. at t. -BuOK1
After adding 1.4 g over 1 hour, stirring was further continued at 21 to 23 ° C. for 4 hours, then poured into pure ice water with stirring, washed thoroughly with water, and filtered by suction. A sufficient vacuum drying was performed at 50 ° C. to obtain a yield of 36.7 g.

Further, toluene / n-hexane = 2/1
Column purification (internal diameter 35 mm, activated alumina (Aluminium Oxide90 active, ne manufactured by MERCK) using a mixed solvent of (vol. Ratio) as a developing solvent.
utral, active1) 17 cm, silica gel (Merck Silica Gel 60, 70-230)
mesh) 17 cm) twice to obtain 20.0 g of 4-
N, N′-bis (p-methylphenyl) amino-α-phenylstilbene (mp = 91.7 ° C.) was obtained.

Next, tris (8-hydroxyquinoline) aluminum (manufactured by Dojindo Co., Ltd.) was used as a light emitting layer (electron transport layer) at a deposition rate of 0.3 nm / s to a thickness of about 40 n.
m.

Next, as an electron injection electrode, an AlLi alloy (manufactured by Kojundo Chemical Co., Ltd., Al / Li weight ratio 99/1)
To form only Li at a low temperature at a deposition rate of about 0.1 nm / s to a film thickness of about 1 nm. Then, the AlLi alloy is further heated to remove only Al from the state where Li has been exhausted to about 1. A film was formed to a film thickness of about 100 nm at a deposition rate of 5 nm / s to obtain a laminated electron injection electrode.

The organic thin film EL device thus prepared was leaked with dry nitrogen in the vapor deposition tank, and then, under a dry nitrogen atmosphere, a lid made of Corning 7059 glass was used as an adhesive (manufactured by Anelva Co., trade name: Supermarket). Back seal 953
-7000) to make a sample.

The organic thin film EL device samples thus obtained were evaluated as follows. The drive is a DC constant current power supply (manufactured by Advantest Corporation, product name: Multi-channel current voltage controller TR616)
The brightness is measured by a luminance meter (manufactured by Tokyo Optical Machine Co., Ltd., trade name: Topcon Luminescence Meter BM-8).
Was measured by

Emission image quality such as uneven brightness and black spots (non-light-emitting portions) was observed with a 50-fold optical microscope. The initial evaluation was performed in a normal laboratory environment at room temperature and normal humidity 12 hours after the glass lid was adhered after the device was deposited, and the luminous efficiency (cd /
A), the driving voltage at the time of light emission at 500 cd / m ² , the density of black spots observable with a microscope (pieces / mm ² ), and the average diameter of the black spots (μm) were evaluated. The initial luminance is 500 cd / m ²
A continuous light emission test was performed in a normal laboratory environment of normal temperature and normal humidity with a constant current drive at a current value of.

From this test, the luminance was reduced by half (250 cd / m
² ), the black spot density after driving for 500 hours (particles / mm ² ), and the average black spot diameter (μm) were evaluated. The sample was stored in a high-temperature and high-humidity (60 ° C. 90% RH) environment for 500 hours to obtain a luminous efficiency (cd / A) of 50%.
The driving voltage at the time of light emission of 0 cd / m ^{2, the} density of black spots observable with a microscope (pieces / mm ² ), and the average diameter of the black spots (μm) were evaluated. The results of these evaluations are shown in (Table 1).

[0081]

[Table 1]

According to the present embodiment, not only is it possible to obtain light emission with excellent visibility by self-emission at a low drive voltage with high light emission efficiency, but also a small decrease in luminance in a continuous light emission test,
Sufficiently long half-life of luminance, low number of black spots (non-light-emitting portions), excellent light emission with high image quality, and increased number of black spots during continuous light emission and storage in a high-temperature, high-humidity environment Thus, a long-life organic thin-film EL element that can be used stably for an extremely long period of time with a small increase in black spot size was realized.

Example 2 In the formation of the hole transport layer of Example 1, 4-N, N'-bis (p-methylphenyl)
Instead of amino-α-phenylstilbene, 1,1-
An organic thin film EL element sample was prepared in the same manner as in Example 1 except that bis (p-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene (manufactured by Annan Co., Ltd.) was used. Evaluation was performed similarly. The results are shown in (Table 1).

Example 3 In the formation of the hole transporting layer of Example 1, N, N'-bis (4'-diphenylamino-
Instead of 4-biphenylyl) -N, N'-diphenylbenzidine, N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-biphenyl-4,
An organic thin film EL element sample was prepared in the same manner as in Example 1 except that 4′-diamine (manufactured by Dojindo Co., Ltd.) was used, and was evaluated in the same manner as in Example 1. The results are shown in (Table 1).

Example 4 In the formation of the hole transport layer of Example 1, N, N'-bis (4'-diphenylamino-
Instead of 4-biphenylyl) -N, N'-diphenylbenzidine, N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-biphenyl-4,
4'-diamine (manufactured by Dojindo Co., Ltd.)
—N, N′-bis (p-methylphenyl) amino-α-
Instead of phenylstilbene, 1,1-bis (p-diethylaminophenyl) -4,4-diphenyl-1,3
-An organic thin film EL element sample was prepared in the same manner as in Example 1 except that butadiene (manufactured by Annan Co., Ltd.) was used.
Evaluation was performed in the same manner as in Example 1.

The results are shown in (Table 1). (Example 5) In the formation of the hole transport layer of Example 1, 4
—N, N′-bis (p-methylphenyl) amino-α-
Instead of phenylstilbene, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-
Organic thin film EL was prepared in the same manner as in Example 1 except that biphenyl-4,4'-diamine (manufactured by Dojindo Co., Ltd.) was used.
An element sample was prepared and evaluated in the same manner as in Example 1.

The results are shown in (Table 1). (Example 6) In the formation of the hole transport layer of Example 1,
N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine and 4-N,
Instead of co-evaporation of N′-bis (p-methylphenyl) amino-α-phenylstilbene, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1 ′
A hole transport layer was similarly formed using only -biphenyl-4,4'-diamine (manufactured by Dojindo Corporation) at a deposition rate of 0.3 nm / s.

In the formation of the electron injecting electrode of Example 1, after forming a laminated electron injecting electrode composed of Li / Al from an AlLi alloy, a Cr powder (manufactured by Kojundo Chemical Co., Ltd.) was used. An electron injection electrode having a thickness of about 100 nm was formed at a deposition rate of 0.5 nm / s to form a three-layer structure of Li / Al / Cr.

Except for forming the hole transport layer and the electron injection electrode in the same manner as in Example 1, the organic thin film EL was used.
An element sample was prepared and evaluated in the same manner as in Example 1.

The results are shown in (Table 1). (Example 7) In the formation of the hole transport layer of Example 1,
N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine and 4-N,
Instead of co-evaporation of N′-bis (p-methylphenyl) amino-α-phenylstilbene, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1 ′
A hole transport layer was similarly formed using only -biphenyl-4,4'-diamine (manufactured by Dojindo Corporation) at a deposition rate of 0.3 nm / s.

Further, following the formation of the electron injection electrode of Example 1, a lead difluoride layer (about 100 nm thick) was formed at a deposition rate of about 1 nm / s from lead difluoride powder (manufactured by Kojundo Chemical Co., Ltd.). Was formed as a protective layer.

An organic thin film EL device sample was prepared in the same manner as in Example 1 except that the hole transport layer was formed and the protective layer was formed on the electron injection electrode in the same manner as in Example 1. Was evaluated.

The results are shown in (Table 1). (Example 8) In the formation of the hole transport layer of Example 1,
N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine and 4-N,
Instead of co-evaporation of N′-bis (p-methylphenyl) amino-α-phenylstilbene, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1 ′
A hole transport layer was similarly formed using only -biphenyl-4,4'-diamine (manufactured by Dojindo Corporation) at a deposition rate of 0.3 nm / s.

Further, following the formation of the electron injection electrode of Example 1, a plasma polymerized film of octafluorocyclobutane having a film thickness of about 3 μm was formed as a protective layer as follows.

For the formation of the octafluorocyclobutane plasma polymerized film, a self-made plasma CVD device different from the high vacuum vapor deposition device used for producing the organic thin film EL device was used.

The configuration of the apparatus is a plasma CVD apparatus having a normal capacitively-coupled parallel plate electrode, and two electrodes (made of SUS304, 120 m in length) arranged in parallel at an interval of 20 mm.
In the case of m × 120 mm × t = 2 mm), one is connected to a high frequency power supply (RFS-200, manufactured by Nippon Vacuum Engineering Co., Ltd.), and the other is an organic thin film EL element formed up to the electron injection electrode as in Example 1. And a configuration that can be connected to ground or a DC power supply. The exhaust device is connected to a rotary pump (D-650DK, manufactured by Nippon Vacuum Engineering Co., Ltd.) having an exhaust speed of 650 liter / min via a valve, and octafluorocyclobutane (4Nup, manufactured by Kanto Denka Kogyo Co., Ltd.) is connected to a mass flow controller (S-Tech). (Manufactured by Co., Ltd.).

The organic thin-film EL element formed up to the electron injection electrode as in Example 1 is arranged on the above-mentioned electrode for arranging the organic thin-film EL element with the electrode connected to the ground,
After exhausting to 0.01 Torr, the flow rate was 100 sccm.
Then, octafluorocyclobutane was introduced into the vacuum chamber, and the exhaust speed was adjusted with a valve so that the pressure became 0.4 Torr. Plasma polymerization was performed at a high frequency power of 100 W for 20 minutes, and a polymer film having a thickness of about 3 μm was formed on the organic thin film EL element formed up to the electron injection electrode as in Example 1.

An organic thin film EL device sample was prepared in the same manner as in Example 1 except that the hole transport layer was formed in this manner, and the plasma polymerized film of octafluorocyclobutane was formed on the electron injection electrode. Evaluation was performed in the same manner as in Example 1.

The results are shown in (Table 1). (Example 9) In the formation of the hole transport layer of Example 1,
N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine and 4-N,
Instead of co-evaporation of N′-bis (p-methylphenyl) amino-α-phenylstilbene, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1 ′
A hole transport layer was similarly formed using only -biphenyl-4,4'-diamine (manufactured by Dojindo Corporation) at a deposition rate of 0.3 nm / s.

Following the formation of the electron injection electrode of Example 1, a plasma polymerized film of octafluorocyclobutane having a thickness of about 3 μm was formed in the same manner as in Example 8.

Following the formation of this octafluorocyclobutane plasma polymerized film, a 200 nm-thick diamond-like thin film was formed as follows using the same plasma CVD apparatus.

The formation of the diamond-like thin film was performed as follows following the formation of the plasma polymerized film of octafluorocyclobutane. After stopping the supply of octafluorocyclobutane and evacuating the inside of the vacuum chamber to 0.01 Torr, methane (manufactured by Osaka Oxygen Co., Ltd., 4N
up) was introduced into the vacuum chamber, and the pumping speed was adjusted with a valve so that the pressure became 0.4 Torr. A DC power supply of -300 V is connected to the substrate arrangement electrode via an LC circuit, and a film is formed at a high frequency power of 200 W for 40 minutes, and the film thickness is about 3 μm.
On the octafluorocyclobutane plasma polymerized film,
Further, a diamond-like thin film having a thickness of about 200 nm was formed.

The same procedure as in Example 1 was carried out except that the hole transport layer was formed in this manner, the octafluorocyclobutane plasma polymerized film was formed on the electron injection electrode, and the diamond-like thin film was formed thereon. Then, an organic thin film EL element sample was prepared and evaluated in the same manner as in Example 1.

The results are shown in (Table 1). Example 10 In the formation of the hole transport layer of Example 1,
N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine and 4-N,
Instead of co-evaporation of N′-bis (p-methylphenyl) amino-α-phenylstilbene, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1 ′
A hole transport layer was similarly formed using only -biphenyl-4,4'-diamine (manufactured by Dojindo Corporation) at a deposition rate of 0.3 nm / s.

In forming the electron injection electrode of Example 1, aluminum was formed on the tris (8-hydroxyquinoline) aluminum deposited film at a deposition rate of about 0.1 nm / s to a thickness of about 5 nm. The film thickness referred to here is a crystal vibration type film thickness meter (CRTM-100 manufactured by Japan Vacuum Engineering Co., Ltd.)
This is a numerical value on the display of 0), and it has been confirmed that it is actually an island-like state before becoming a film. Subsequent to the formation of the island-shaped aluminum, a laminated electron injection electrode composed of Li / Al was formed from an AlLi alloy in the same manner as in Example 1.

An organic thin film EL was produced in the same manner as in Example 1 except that the hole transport layer and the electron injection electrode were formed in this manner.
An element sample was prepared and evaluated in the same manner as in Example 1.

The results are shown in (Table 1). (Comparative Example 1) In the formation of the hole transport layer of Example 1,
N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine and 4-N,
Instead of co-evaporation of N′-bis (p-methylphenyl) amino-α-phenylstilbene, N, N′-bis (4′-diphenylamino-4-biphenylyl) -N,
Using only N′-diphenylbenzidine, 0.3 nm
An organic thin film EL device sample was prepared in the same manner as in Example 1 except that the hole transport layer was similarly formed at a deposition rate of / s, and the evaluation was performed in the same manner as in Example 1.

The results are shown in (Table 1). (Comparative Example 2) In the formation of the hole transport layer of Example 1,
N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine and 4-N,
Instead of co-evaporation of N′-bis (p-methylphenyl) amino-α-phenylstilbene, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1 ′
Organic thin film in the same manner as in Example 1 except that a hole transport layer was similarly formed at a deposition rate of 0.3 nm / s using only -biphenyl-4,4'-diamine (manufactured by Dojindo Corporation). An EL element sample was prepared and evaluated in the same manner as in Example 1.

The results are shown in (Table 1). (Comparative Example 3) In the formation of the hole transport layer of Example 1,
N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine and 4-N,
Instead of co-evaporation of N′-bis (p-methylphenyl) amino-α-phenylstilbene, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1 ′
-Biphenyl-4,4'-diamine (manufactured by Dojin Chemical Co., Ltd.) and rubrene (manufactured by Tokyo Chemical Industry Co., Ltd.) were co-evaporated at a deposition rate of 0.3 nm / s and 0.015 nm / s, respectively, to form a film. Example 1 except that the thickness was about 80 nm.
An organic thin film EL element sample was prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1.

The results are shown in (Table 1).

[0111]

As described above, according to the present invention, the hole transport layer is composed of at least two types of hole transport materials and contains a hole transport material having an asymmetric molecular structure. The hole transporting layer is composed of at least two or more kinds of hole transporting materials, and contains at least a main hole transporting material and a hole transporting material having a molecular weight of 2/3 or less of its molecular weight, or Having a layered structure of a layer mainly composed of aluminum and a layer mainly composed of chromium, or having a lead difluoride layer as a protective layer on the electron injection electrode, or an octa layer on the electron injection electrode. By having a plasma polymerized film of fluorocyclobutane with a thickness of 1 μm or more, or High luminous efficiency by having a polymerized film and a protective layer formed on the plasma polymerized film, or by forming an electron injection electrode after forming aluminum in an island shape on an organic thin film. In addition to the self-emission at low driving voltage, excellent light emission with excellent visibility can be obtained, and even in a continuous light emission test, the luminance decrease is small, a sufficiently long luminance half life can be obtained, and the black point (non-light emitting part) Light emission with excellent image quality is obtained.
Further, it is an object of the present invention to provide a long-life organic thin-film EL element which has a small increase in the number of black spots and a small increase in the size of black spots even during continuous light emission or storage in a high-temperature and high-humidity environment, and can be used stably for an extremely long period of time. It is possible.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hisanori Sugiura 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Yoshinobu Murakami 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (30)

[Claims] An organic thin-film EL device comprising an electron injection electrode, a hole injection electrode, and a hole transport layer provided at least between the electron injection electrode and the hole injection electrode on a transparent substrate. An organic thin-film EL device, wherein the hole transport layer is made of at least two types of hole transport materials and contains a hole transport material having an asymmetric molecular structure. 2. The method according to claim 1, wherein the hole transporting layer has the following general formula: (Wherein R1, R2, R3, R4, and R5 may be the same or different; R1, R2, and R3 represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group; R4 and R5 represent a hydrogen atom or a lower alkyl group; , A lower alkoxy group, or a chlorine atom). 3. The method according to claim 1, wherein said hole transport layer is mainly composed of N, N'-bis (4'-diphenylamino-4-biphenylyl)-.
2. The organic thin film EL device according to claim 1, wherein the organic thin film EL device is made of N, N'-diphenylbenzidine. 4. The content of the hole transporting material having an asymmetric molecular structure in the hole transporting layer is 30% by weight.
The organic thin film EL device according to claim 1, wherein: 5. An organic thin-film EL device having an electron injection electrode, a hole injection electrode, and at least a hole transport layer provided between the electron injection electrode and the hole injection electrode on a transparent substrate. Wherein the hole transport layer is made of at least two types of hole transport materials, and contains at least a main hole transport material and a hole transport material having a molecular weight of 2/3 or less of its molecular weight. Thin film EL element. 6. A main hole transport material of the hole transport layer,
Wherein R1, R2, R3, R4, and R5 may be the same or different, and R1, R2, and R3 represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group;
4. The organic thin film EL device according to claim 5, wherein R5 is a hole transporting material represented by a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom. 7. The method according to claim 7, wherein the hole transport layer is mainly composed of N, N'-bis (4'-diphenylamino-4-biphenylyl) -N,
The organic thin-film EL device according to claim 5, wherein the organic thin-film EL device is constituted by N'-diphenylbenzidine. 8. The content of the hole transport material having a molecular weight of not more than 2/3 of the molecular weight of the main hole transport material in the hole transport layer is not more than 30% by weight. The organic thin-film EL device according to any one of claims 5 to 7, wherein 9. An organic thin-film EL device comprising an electron injection electrode, a hole injection electrode, and a hole transport layer provided at least between the electron injection electrode and the hole injection electrode on a transparent substrate. Wherein the hole transport layer has at least a general formula (Formula 1)
(Wherein R1, R2, R3, R4, and R5 may be the same or different; R1, R2, and R3 represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group; R4 and R5 represent a hydrogen atom or a lower alkyl group; , A lower alkoxy group or a chlorine atom) and a host compound represented by the following general formula: (Wherein R1, R2, R3, and R4 may be the same or different and each represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group). EL element. 10. The method according to claim 10, wherein the host compound is N, N'-bis (4'-diphenylamino-4-biphenylyl) -N,
N′-diphenylbenzidine, wherein the guest compound is 4-
The organic thin film EL device according to claim 9, wherein the organic thin film EL device is N, N'-bis (p-methylphenyl) amino-α-phenylstilbene. 11. The weight ratio of the host compound in the hole transporting layer is 70% or more, and the weight ratio of the guest compound is 30% or less in the hole transport layer. 11. The organic thin film EL device according to 9 or 10. 12. An organic thin-film EL device having an electron injection electrode and a hole injection electrode on a transparent substrate and at least a hole transport layer provided between the electron injection electrode and the hole injection electrode. Wherein the hole transport layer has at least the general formula (Chemical Formula 1) (wherein R1, R2, R3, R4, and R5 may be the same or different, and R1, R2, and R3 are a hydrogen atom, a lower alkyl group, An alkoxy group, and R4 and R5 each represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom), and a host compound represented by the following general formula: (Wherein R1, R2, R3, and R4 may be the same or different and include a hydrogen atom, a chlorine atom, a methyl group, a methoxy group,
A dimethylamino group, a diethylamino group, a diphenylamino group, or a dibenzylamino group). 13. The method according to claim 13, wherein the host compound is N, N'-bis (4'-diphenylamino-4-biphenylyl) -N,
N′-diphenylbenzidine, wherein the guest compound is 1,
13. The organic thin-film EL device according to claim 12, wherein the organic thin-film EL device is 1-bis (p-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene. 14. The weight ratio of the host compound in the hole transport layer is 70% or more, and the weight ratio of the guest compound is 30% or less in the hole transport layer. 14. The organic thin film EL device according to 12 or 13. 15. An organic thin-film EL device having an electron injection electrode and a hole injection electrode on a transparent substrate and at least a hole transport layer provided between the electron injection electrode and the hole injection electrode. Wherein the hole transport layer has at least the following general formula: (Wherein R 1 and R 2 may be the same or different and represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a substituted or unsubstituted aryl group, and R 3 represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or A host compound represented by the general formula (Chemical Formula 2)
R2, R3, and R4 may be the same or different and each represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group). 16. The method according to claim 16, wherein the host compound is N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1 ′.
-Biphenyl-4,4'-diamine, wherein the guest compound is 4-N, N'-bis (p-methylphenyl) amino-
The organic thin-film EL device according to claim 15, wherein the organic thin-film EL device is α-phenylstilbene. 17. The method according to claim 17, wherein the proportion of the host compound in the hole transport layer is at least 70% by weight, and the proportion of the guest compound is at most 30% by weight. Item 17. The organic thin film EL device according to Item 15 or 16. 18. An organic thin-film EL device comprising an electron injection electrode, a hole injection electrode, and a hole transport layer provided at least between the electron injection electrode and the hole injection electrode on a transparent substrate. Wherein the hole transport layer has at least a general formula (Chemical Formula 4) (wherein R 1 and R 2 may be the same or different;
A host compound represented by a hydrogen atom, a lower alkyl group, a lower alkoxy group, a substituted or unsubstituted aryl group, and R 3 represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom); (Wherein R1, R2, R3, and R4 may be the same or different and include a hydrogen atom, a chlorine atom, a methyl group, a methoxy group, a dimethylamino group, a diethylamino group, a diphenylamino group, or a dibenzylamino And a guest compound represented by the following formula: 19. The method according to claim 19, wherein the host compound is N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1 '.
-Biphenyl-4,4'-diamine, wherein the guest compound is 1,1-bis (p-diethylaminophenyl) -4,
19. The organic thin-film EL device according to claim 18, wherein the organic thin-film EL device is 4-diphenyl-1,3-butadiene. 20. The method according to claim 20, wherein the proportion of the host compound in the hole transport layer is at least 70% by weight, and the proportion of the guest compound is at most 30% by weight. Item 20. The organic thin-film EL device according to item 18 or 19. 21. An organic thin-film EL device having an electron injection electrode, a hole injection electrode, and a hole transport layer provided at least between the electron injection electrode and the hole injection electrode on a transparent substrate. Wherein the hole transport layer has at least the general formula (Chemical Formula 1) (wherein R1, R2, R3, R4, and R5 may be the same or different, and R1, R2, and R3 are a hydrogen atom, a lower alkyl group, Represents an alkoxy group, and R4 and R5 represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom, and a host compound represented by the general formula (Formula 4) (wherein R1 and R2 are the same or different. May be
A hydrogen atom, a lower alkyl group, a lower alkoxy group, a substituted or unsubstituted aryl group, and R3 represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a chlorine atom). An organic thin-film EL device characterized by the following. 22. The method according to claim 20, wherein the host compound is N, N′-bis (4′-diphenylamino-4-biphenylyl) -N,
N′-diphenylbenzidine, wherein the guest compound is N,
22. The organic thin-film EL device according to claim 21, wherein the organic thin-film EL device is N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine. 23. The weight ratio of the host compound in the hole transport layer is 70% or more, and the weight ratio of the guest compound is 30% or less in the hole transport layer. 23. The organic thin film EL device according to 21 or 22. 24. An organic thin-film EL device comprising a transparent substrate on which at least a hole injection electrode, an organic thin-film layer, and an electron injection electrode are laminated, wherein the electron injection electrode is a layer mainly composed of aluminum. And an organic thin film EL having a laminated structure of layers mainly composed of chromium
element. 25. An organic thin-film EL device comprising a transparent substrate on which at least a hole injection electrode, an organic thin-film layer, and an electron injection electrode are laminated, wherein a lead difluoride layer is provided on the electron injection electrode. An organic thin-film EL device characterized by the above-mentioned. 26. An organic thin film EL device comprising a transparent substrate and at least a hole injection electrode, an organic thin film layer, and an electron injection electrode laminated thereon, wherein a plasma polymerized film of octafluorocyclobutane is formed on the electron injection electrode. Having a thickness of 1 μm or more. 27. An organic thin film EL device comprising a transparent substrate and at least a hole injection electrode, an organic thin film layer, and an electron injection electrode laminated thereon, wherein a plasma polymerized film of octafluorocyclobutane is formed on the electron injection electrode. And a protective layer formed on the plasma polymerized film. 28. A method of manufacturing an organic thin-film EL device comprising a transparent substrate and at least a hole injection electrode, an organic thin-film layer, and an electron injection electrode laminated on each other, wherein octafluorocyclobutane is formed on the electron injection electrode. A method for manufacturing an organic thin film EL device, comprising: forming a plasma polymerized film; and forming a protective layer on the plasma polymerized film. 29. An organic thin film EL device comprising a transparent substrate and at least a hole injecting electrode, an organic thin film layer, and an electron injecting electrode laminated thereon, after forming aluminum in an island shape on the organic thin film. And an organic thin-film EL device comprising the electron injection electrode. 30. A method of manufacturing an organic thin-film EL device comprising a transparent substrate and at least a hole injection electrode, an organic thin-film layer, and an electron injection electrode laminated on each other. The method of manufacturing an organic thin-film EL device, wherein, in the forming step, the electron injection electrode is formed after the step of forming aluminum in an island shape on the organic thin film.