JP2002280176A - Thin film el element and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve a problem that it is difficult to realize an element having high efficiency, a low driving voltage and a long service life by a structure composed by stacking a positive hole transporting layer using a positive hole transporting material having a symmetrical structure such as generally used tetraphenyldiamine and an electron transporting luminescent layer. SOLUTION: A positive hole transporting layer formed of a positive hole transporting substance having a specific asymmetrical structure is used as the positive hole transporting layer. For the positive hole transporting layer, a material group having a specific relationship among ionization potentials thereof is used. A layer formed of a specific material is used for the positive hole transporting layer or an electron transporting layer. A phosphorescent substance is included in the luminescent layer, and the content and the driving method thereof have a particular relationship.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-film electroluminescence (EL) device, and more particularly to a self-luminous device which can be used as a light source for various purposes such as a flat type self-luminous display device, communication, lighting and the like. is there.

[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. There are problems such as insufficient characteristics and an increase in cost as a panel. Under such circumstances, the thin-film EL as a new light-emitting element that is self-luminous, has excellent visibility, has a high response speed, and can be expected to be used in a wide range of applications.
Expectations are gathering on the device. In particular, thin-film EL devices that use organic materials that can use simple film-forming processes such as evaporation and coating at room temperature for all or some of the layers of the device are also called organic EL devices. Many studies have been conducted due to the attractiveness of cost.

A thin-film EL element (organic EL element) is one in which electrons and holes are injected from electrodes to obtain light emission by recombination, and many studies have been made for a long time. It was far from being applied to a typical light emitting element.

Under such circumstances, a device proposed by Tang et al. In 1987 (CW Tang and
S. A. Vanslyke: Appl. Phys. Le
tt. 51 (1987) 913. ) Is a device having a transparent hole injecting electrode, a light emitting functional layer, and an electron injecting electrode on a transparent substrate, wherein the light emitting functional layer has a structure in which a hole transport layer and an electron transporting light emitting layer are laminated. Further, MgAg was used 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. With such a thin-film laminated device configuration, light emission can be obtained with high efficiency. Tang
Et al. Have a configuration such as this at a low voltage of 10 V or less.
High brightness of 0 cd / m ² or more and high efficiency of 1.5 lm / W or more are realized. The report of Tang et al. Has been a trigger for ongoing active studies.

[0005] The thin film EL generally studied below is
The (organic EL) element will be outlined.

Each layer of the device is formed by laminating a hole injection electrode, a light emitting function layer, and an electron injection electrode in this order on a transparent substrate.
The light emitting functional layer is often a laminated film such as a hole transporting layer and an electron transporting light emitting layer. 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 structures have been studied for the light emitting functional layer, but basically a structure in which an electron transporting light emitting layer is laminated on a hole transporting layer is widely used. Here, the hole transport layer is formed of a symmetric hole transport material having a para-linked dimer of triphenylamine as a skeleton (for example, N, N'-bis (3-
Methylphenyl) -N, N′-diphenylbenzidine;
N, N'-bis (α-naphthyl) -N, N'-diphenylbenzidine, etc.) is formed to a thickness of several tens nm by vacuum evaporation, and the electron transporting light emitting layer is formed of tris (8-quinolinolato) aluminum or the like. Is formed to a thickness of several tens nm by vacuum evaporation.

Generally, a portion where electrons and holes recombine and emit light is called a light emitting layer. If this portion is near the hole injection electrode or the electron injection electrode, exciton generated by the recombination will cause non-emission. The luminous efficiency is reduced. In order to prevent this phenomenon and to alleviate the influence of the surface condition of the underlying substrate, it is necessary to provide a hole transport layer on the hole injection electrode side and provide an electron transport layer on the electron injection electrode side. It is. Tris (8-quinolinolato) aluminum is a green light-emitting electron-transporting material, and is used as a layer serving as both a light-emitting layer and an electron-transport layer. It is thought that the portion on the electron injection electrode side functions as an electron transport layer. In this specification, not only the light emitting layer portion that actually emits light, but also a portion having a hole transport function contributing to a light emitting function and a portion having an electron transport function are collectively referred to as a light emitting functional layer.

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.

If such elements are arranged in a matrix and scanned in a line-sequential manner to emit light, they are useful not only as simple light-emitting elements but also as display devices for image information. In this case, for example, when driving is performed by sequentially scanning in the vertical direction and emitting light in a matrix of 480 pixels vertically × 640 pixels horizontally,
The light emission time of each pixel is 1/480. For example, in order to obtain an average luminance of 100 candela as the brightness of the panel, the actual light emission luminance of each pixel should be 480 times and emit light at 48,000 candela. .

[0013]

As described above, a multi-layered device structure with separated functions proposed by Tang et al. Is used. In particular, a symmetric compound having a triphenylamine dimer skeleton as a hole transport material is used. In addition, M as an electron injection electrode
By using an alloy of a metal having a low work function such as gAg and a low electron injection barrier and a metal having a relatively large work function and being stable, a sufficient luminance of several hundred candela can be obtained even at a low voltage of several V. Can be realized.

However, N, N'-bis (3-methylphenyl) -N, which has been widely used so far,
A symmetrical compound having a triphenylamine dimer skeleton such as N'-diphenylbenzidine as a skeleton is relatively easy to aggregate, associate, or crystallize because the molecule is relatively planar and symmetrical. It is difficult to uniformly obtain a high hole transport ability. N, N'-bis (α-naphthyl)-, in which one of the phenyl groups of triphenylamine is substituted with a naphthyl group to improve the planarity.
Many studies have been made on materials such as N, N'-diphenylbenzidine for improving characteristics, but at present, there is no device having sufficient characteristics in terms of efficiency and life. In particular, when used as a matrix-type line-sequential scanning display as described above, since the peak luminance is large, the driving voltage increases, power consumption increases, reliability decreases, and the cost of the driving circuit decreases. Besides rising,
The life tends to be shorter than when used in a continuous light emitting state, and an element having a longer life and excellent reliability has been demanded.

[0015]

In view of such a situation,
The authors used materials with various physical properties, laminated functional thin films with various characteristics in various configurations, and evaluated them from the viewpoint of luminous efficiency and life. The present inventors have found that a high-efficiency and long-life element can be realized by using a combination of the above materials or using a specific material in a specific layer configuration, thereby completing the present invention. Particularly, as a hole transporting material, a compound having an asymmetrical triphenylamine moiety and an α-phenylstilbene moiety and having extremely poor planarity was used, and it was found that remarkable improvement in characteristics was observed. The invention has been completed.

Specifically, the thin-film EL device according to the first aspect of the present invention provides a light emitting function provided on a transparent substrate, provided between a hole injection electrode and an electron injection electrode, and at least between the hole injection electrode and the electron injection electrode. And a hole transport material used in the light-emitting functional layer is mainly represented by the following general formula:

[0017]

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(Wherein R1, R2, and R3 may be the same or different and each represent a hydrogen atom, an alkyl group, or an alkoxy group).

The thin film EL device according to the second aspect of the present invention is characterized in that the compound represented by the general formula of the first aspect is [4- (2,2-diphenylvinyl) phenyl] [4- (diphenylamino) phenyl] phenyl A thin film EL device characterized by being an amine.

The thin-film EL device according to the third aspect of the present invention is characterized in that the compound represented by the general formula described in the first aspect is [4- (2,
2-diphenylvinyl) phenyl] (4-t-butylphenyl) {4-[(4-t-butylphenyl) phenylamino] phenyl} amine.

The thin film EL device according to the fourth aspect of the present invention is characterized in that the compound represented by the general formula described in the first aspect is [4- (2,
A thin film EL comprising 2-diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4-methoxyphenyl) phenylamino] phenyl} amine
Element.

In the thin film EL device according to the fifth invention, the compound represented by the general formula described in the first invention is [4- (2,
A thin film EL comprising 2-diphenylvinyl) phenyl] (2-methoxyphenyl) {4-[(2-methoxyphenyl) phenylamino] phenyl} amine
Element.

In the thin film EL device according to the sixth invention, the compound represented by the general formula described in the first invention is [4- (2,
2-diphenylvinyl) phenyl] (2,3-dimethoxyphenyl) ｛4-[(2,3-dimethoxyphenyl)
[Phenylamino] phenyl} amine.

A thin-film EL device according to a seventh aspect of the present invention is a thin-film EL device comprising a transparent substrate and a hole injection electrode and an electron injection electrode, and at least a light emitting function layer provided between the hole injection electrode and the electron injection electrode. Wherein the hole transport material used in the light emitting functional layer is mainly represented by the following general formula:

[0025]

Embedded image

(Wherein R1, R2 and R3 may be the same or different, and include a hydrogen atom, an alkyl group, an alkoxy group,
Represents a substituted or unsubstituted aryl group, and R1 and R2 or R2 and R3 may each form a ring. Where R
4 represents a hydrogen atom or an alkyl group. A thin film EL device characterized by being a compound described in (1).

An organic thin film EL device according to an eighth aspect of the present invention is the organic thin film EL device according to the seventh aspect, wherein the compound represented by the general formula described in the seventh aspect is $ 4-
Thin film EL comprising [4- (2,2-diphenylvinyl) phenyl] phenyl} diphenylamine
Element.

The thin film EL device according to the ninth aspect of the present invention is characterized in that the compound represented by the general formula described in the seventh aspect is {4- [4-
(2,2-diphenylvinyl) phenyl] phenyl} bis (2,3-dimethoxyphenyl) amine.

The thin film EL device according to the tenth aspect of the present invention has
The compound represented by the general formula described in the invention of the above is {4- [4
-(2,2-diphenylvinyl) phenyl] phenyl}
A thin-film EL device comprising di (2H-benzo [d] 1,3-dioxolan-4-yl) amine.

The thin film EL device according to the eleventh aspect of the present invention includes
The compound represented by the general formula described in the invention of the above is {4- [4
-(2,2-diphenylvinyl) phenyl] phenyl}
A thin film EL device characterized by being bis (4-t-butylphenyl) amine.

A twelfth aspect of the present invention is directed to the
The compound represented by the general formula described in the invention of the above is {4- [4
-(2,2-diphenylvinyl) -2-methylphenyl] -3-methylphenyl @ bis (4-t-butylphenyl) amine.

A thirteenth aspect of the present invention is a thin film EL device comprising:
The light-emitting functional layer according to any one of the inventions to the twelfth invention includes a structure in which an electron-transporting light-emitting layer is laminated on at least a hole-transporting layer, and the hole-transporting layer mainly includes the hole-transporting material. This is a thin film EL device characterized by being performed.

Further, the thin-film EL device according to the fourteenth invention is characterized in that
3. The thin-film EL device according to claim 3, wherein the electron-transporting light-emitting layer mainly comprises tris (8-quinolinolato) aluminum or a derivative thereof.

The fifteenth aspect of the present invention provides a thin film EL device comprising:
3. The thin-film EL device according to claim 3, wherein the electron-transporting light-emitting layer is mainly made of tris (4-methyl-8-quinolinolato) aluminum.

A thin-film EL device according to a sixteenth aspect of the present invention is a thin-film EL device comprising a transparent substrate and a hole injection electrode and an electron injection electrode, and at least a light-emitting functional layer provided between the hole injection electrode and the electron injection electrode. Wherein the hole transport material used in the light emitting functional layer has at least the following general formula:

[0036]

Embedded image

(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;
R5 is a hydrogen atom, a lower alkyl group, a lower alkoxy group,
Or a chlorine atom) and a general formula shown below

[0038]

Embedded image

Wherein R 1, R 2, R 3 and R 4 may be the same or different and each represent a hydrogen atom, a lower alkyl group or a lower alkoxy group; ) And a hole transporting material having a lower ionization potential than both of the hole transporting material represented by the chemical formula (4).

The thin-film EL device according to the seventeenth invention is characterized in that
The hole transporting material represented by the formula (3) according to the invention of claim 6,
A thin-film EL device comprising N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine.

The thin-film EL device according to the eighteenth aspect is characterized in that
The hole transport material represented by Chemical Formula 4 in the invention of the sixth or seventeenth invention is 4-N, N-diphenylamino-α-
The thin film as described above, which is phenylstilbene
EL element.

A thin film EL device according to a nineteenth aspect of the present invention is the thin film EL device according to any one of the sixteenth to eighteenth aspects.
And a hole transporting material having a lower ionization potential than either of the hole transporting material represented by the formula (4) and 4-N, N-bis (4-methylphenyl). A thin-film EL device comprising amino-α-phenylstilbene.

The twentieth aspect of the present invention provides a thin film EL device comprising:
The light-emitting functional layer according to any one of the sixth to nineteenth aspects, includes a structure in which an electron-transporting light-emitting layer is laminated on at least a hole-transport layer, and the hole-transport layer is mainly composed of the hole-transport layer. A thin film EL device comprising a material.

A thin-film EL device according to a twenty-first aspect of the present invention comprises
The electron transporting light emitting layer according to the invention is mainly composed of tris (8-quinolinolato) aluminum or a derivative thereof.

The thin-film EL device according to the twenty-second invention is characterized in that
0. The thin-film EL device according to claim 1, wherein the electron-transporting light-emitting layer is mainly made of tris (4-methyl-8-quinolinolato) aluminum.

A thin-film EL device according to a twenty-third aspect of the present invention is a thin-film EL device comprising a transparent substrate and a hole-injection electrode, an electron-injection electrode and at least a light-emitting functional layer provided between the hole-injection electrode and the electron-injection electrode. The electron injection electrode has a laminated structure of an ultrathin metal lithium film and an aluminum film.

The thin-film EL device according to the twenty-fourth aspect of the present invention is characterized in that
3. The thin film EL device according to the third aspect, wherein the ultrathin metal lithium film has a thickness of 5 Å to 25 Å.

Further, a thin-film EL device according to a twenty-fifth aspect of the present invention is a thin-film EL device comprising a transparent substrate and a hole injection electrode and an electron injection electrode, and at least a light-emitting functional layer provided between the hole injection electrode and the electron injection electrode. The electron injection electrode has a laminated structure of a phenyllithium thin film and an aluminum film.

The thin-film EL device according to the twenty-sixth aspect is characterized in that
The light-emitting functional layer according to any one of the third to twenty-fifth aspects includes a structure in which an electron-transporting light-emitting layer is laminated on at least a hole-transporting layer, and the electron-transporting light-emitting layer is mainly composed of tris (8 -Quinolinolato) A thin-film EL device comprising aluminum or a derivative thereof.

The thin-film EL device according to the twenty-seventh aspect is characterized in that
The light-emitting functional layer according to any one of the third to twenty-fifth aspects includes a structure in which an electron-transporting light-emitting layer is laminated on at least a hole-transporting layer, and the electron-transporting light-emitting layer is mainly composed of tris (4 -Methyl-8-quinolinolato) aluminum.

A thin-film EL device according to a twenty-eighth aspect of the present invention has a hole injection electrode and an electron injection electrode on a transparent substrate, and a light-emitting functional layer provided between the hole injection electrode and the electron injection electrode. A thin-film EL element, wherein the thin-film shape of the light-emitting functional layer is such that an average value W1 of a period of in-plane irregularities is a pixel period W2.
The average D1 of the difference between the concave portion and the convex portion measured in a direction perpendicular to the substrate surface, which is smaller than that of D1, is 1 of the film thickness D2 of the light emitting functional layer.
/ 2 or more and W2 or less, and W1
And a ratio W1 / D1 of not less than 10 and a coating type medium resistance conductive layer between the hole injection electrode and the light emitting functional layer.

A thin-film EL device according to a twenty-ninth aspect of the present invention is a thin-film EL device comprising a transparent substrate and at least a hole injection electrode, a coating-type medium-resistance conductive layer, a light-emitting function layer, and an electron injection electrode.
A thin-film EL device, wherein the thin-film shape of the light-emitting functional layer is such that the area of the concave portion as viewed from the light-emitting surface of the substrate is larger than the area of the convex portion.

The thin-film EL device according to a thirtieth aspect of the present invention is characterized in that
The thin film shape of the light emitting functional layer according to the ninth aspect, wherein the average value W1 of the in-plane unevenness period is smaller than the pixel period W2, and the concave and convex portions are measured in the direction perpendicular to the substrate surface. The difference D1 is equal to or more than の of the thickness D2 of the light emitting functional layer and equal to or less than W2, and the ratio W1 between W1 and D1 is W.
1 / D1 is 10 or more.

A thin-film EL device according to a thirty-first aspect of the present invention is characterized in that
The ionization potential of the medium resistance conductive layer according to any one of the eighth invention to the thirtieth invention is from 0.4 eV to -0.2 eV as compared with the ionization potential of the hole transport material used in the light emitting functional layer. Is a thin-film EL element.

A thin-film EL device according to a thirty-second aspect of the present invention is a thin-film EL device comprising a transparent substrate and a hole injection electrode and an electron injection electrode, and at least a light-emitting functional layer provided between the hole injection electrode and the electron injection electrode. A thin-film EL device comprising: the light-emitting functional layer having at least Buckminsterfullerene C60 or C60.
A thin film EL device comprising a layered structure of a hole transport layer containing 70 and an electron transporting light emitting layer.

A thin-film EL device according to a thirty-third aspect of the present invention is a thin-film EL device comprising a transparent substrate and a hole injection electrode and an electron injection electrode, and at least a light emitting function layer provided between the hole injection electrode and the electron injection electrode. Wherein the light-emitting functional layer comprises a laminated structure of at least a hole-transporting light-emitting layer and an electron-transporting layer containing at least buckminsterfullerene C60 or C70. It is.

A thin-film EL device according to a thirty-fourth aspect of the present invention is a thin-film EL device comprising a transparent substrate and a hole injection electrode and an electron injection electrode, and at least a light emitting functional layer provided between the hole injection electrode and the electron injection electrode. A thin-film EL device comprising: the light-emitting functional layer having a stacked structure of at least a hole transport layer containing buckminsterfullerene C60 or C70, a light-emitting layer, and an electron transport layer containing buckminsterfullerene C60 or C70. Is a thin-film EL element.

A thirty-fifth aspect of the present invention provides a thin-film EL device, comprising: a transparent substrate with a hole injection electrode and an electron injection electrode, and at least a light emitting functional layer provided between the hole injection electrode and the electron injection electrode. Wherein the light-emitting functional layer includes a layered structure of a hole transport layer containing at least carbon nanotubes and an electron-transporting light-emitting layer.

A thin-film EL device according to a thirty-sixth aspect is characterized in that a hole injection electrode and an electron injection electrode, and at least a light emitting function layer provided between the hole injection electrode and the electron injection electrode, are formed on a transparent substrate. Wherein the light-emitting functional layer has a laminated structure of at least a hole-transporting light-emitting layer and an electron-transporting layer containing at least carbon nanotubes.

A thirty-seventh aspect of the present invention provides a thin-film EL device, comprising: a transparent substrate with a hole injection electrode and an electron injection electrode, and at least a light emitting functional layer provided between said hole injection electrode and the electron injection electrode. A thin-film EL device comprising: a light-emitting functional layer, wherein the light-emitting functional layer includes a stacked structure of a hole-transporting layer containing at least an organic polysilane having a number average molecular weight of 10,000 or more and an electron-transporting light-emitting layer. EL element.

A thirty-eighth thin film EL device according to the present invention
The hole transport layer containing the organic polysilane according to the invention of the seventh aspect,
The coating film, and the thin film shape of the light emitting function layer, the average value W1 of the period of the in-plane irregularities is smaller than the pixel period W2, and, the concave and convex measured in the direction perpendicular to the substrate surface. The average D1 of the difference between the parts is not less than の of the thickness D2 of the light emitting functional layer and not more than W2, and the ratio W1 / D1 of W1 to D1 is not less than 10. Thin film EL
Element.

A thin-film EL device according to a thirty-ninth aspect of the present invention is a thin-film EL device comprising a transparent substrate and a hole injection electrode and an electron injection electrode, and at least a light emitting function layer provided between the hole injection electrode and the electron injection electrode. Wherein the light emitting functional layer includes a laminated structure of at least an n-type amorphous silicon layer and a hole transporting light emitting layer.
L element.

A thin-film EL device according to a fortieth aspect of the present invention is characterized in that
9. The thin-film EL device according to claim 9, wherein the thickness of the n-type amorphous silicon layer is 50 nm or more and 250 nm or less.

A thin-film EL device according to a forty-first aspect of the present invention provides a thin-film EL device comprising a hole injection electrode and an electron injection electrode on a transparent substrate, and at least a light emitting function layer provided between the hole injection electrode and the electron injection electrode. Wherein the light-emitting functional layer includes at least a layered structure of a hole-transporting layer and an electron-transporting light-emitting layer, and the electron-transporting light-emitting layer mainly includes an electron-transporting host material and a guest When the number of molecules of the phosphorescent material doped with the phosphorescent material is 1/50 or more and 10 times or less of the number of carriers injected into the device during one light emission period. There is provided a thin film EL element.

A thin-film EL device according to a forty-second aspect of the present invention comprises a transparent substrate and a hole injection electrode and an electron injection electrode, and at least a light emitting functional layer provided between the hole injection electrode and the electron injection electrode. A light-emitting functional layer, wherein the light-emitting functional layer includes at least a laminated structure of an electron-transporting layer and a hole-transporting light-emitting layer, and the hole-transporting light-emitting layer mainly includes a hole-transporting host material. A phosphorescent material doped as a guest substance, and the number of molecules of the doped phosphorescent material is 1/50 or more and 10 times the number of carriers injected into the device during one light emitting period. A thin film EL device characterized by the following.

A driving method for a thin-film EL device according to a forty-third aspect of the present invention is a method for driving a thin-film EL element, comprising: a hole injection electrode and an electron injection electrode on a transparent substrate; A driving method of the thin-film EL device having a light-emitting functional layer, wherein the light-emitting functional layer includes at least a layered structure of a hole-transporting layer and an electron-transporting light-emitting layer, and the electron-transporting light-emitting layer mainly includes an electron-transporting layer. In a thin-film EL device composed of an active host material and a phosphorescent material doped with a guest substance, the number of carriers injected into the device during one light emission period is reduced by the number of molecules of the doped phosphorescent material. A method for driving a thin-film EL device, wherein the ratio is 1/10 or more and 50 times or less.

A forty-fourth aspect of the invention provides a method of driving a thin-film EL device, comprising: a hole injection electrode and an electron injection electrode on a transparent substrate; and a light emitting function provided at least between the hole injection electrode and the electron injection electrode. A driving method of the thin-film EL device having a light-emitting functional layer, wherein the light-emitting functional layer includes at least a laminated structure of an electron-transporting layer and a hole-transporting light-emitting layer, and the hole-transporting light-emitting layer is mainly positive. In a thin-film EL device composed of a hole-transporting host material and a phosphorescent material doped with a guest substance, the number of carriers injected into the device during one emission period is limited by the number of molecules of the doped phosphorescent material. A method for driving a thin film EL element, wherein the number is 1/10 or more and 50 times or less.

A forty-fifth aspect of the invention is directed to the thin film EL device according to the third aspect.
The thin-film EL device according to any one of 2, 35, 37, 38 and 41, wherein the electron-transporting light-emitting layer is mainly composed of tris (8-quinolinolato) aluminum or a derivative thereof.

The thin-film EL device according to the forty-sixth aspect is characterized in that
The electron-transporting light-emitting layer according to any one of 2, 35, 37, 38 and 41 is mainly composed of tris (4-methyl-
8-quinolinolato) A thin-film EL device comprising aluminum.

A forty-seventh invention provides a method for driving a thin-film EL device, wherein the electron-transporting light-emitting layer according to the forty-third invention is mainly composed of tris (8-quinolinolato) aluminum or a derivative thereof. This is a method for driving an EL element.

A forty-eighth invention provides a method for driving a thin-film EL device, wherein the electron-transporting light-emitting layer according to the forty-third invention is mainly composed of tris (4-methyl-8-quinolinolato) aluminum. This is a method for driving a thin film EL element.

[0072]

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

The thin-film EL device of the present invention comprises a hole injection electrode and an electron injection electrode on a transparent substrate, and at least a light emitting function layer provided between the hole injection electrode and the electron injection electrode. Here, the light emitting functional layer collectively refers to layers involved in a process of emitting light by holes and electrons injected from both electrodes, and as is generally known, actually a hole transport layer and an electron A layered structure with a transportable light-emitting layer, a layered structure of a hole-transport layer, a light-emitting layer, and an electron-transport layer, and a layered structure of layers such as a hole-injection layer and an electron-injection layer. I do.

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. In general, one of the electron injection electrode and the hole injection electrode needs to be transparent, and in many cases, a transparent electrode is provided on a transparent substrate to take out light emission. Light emission may be obtained by forming a film and using the upper electrode as a transparent electrode. Normal,
In many cases, a transparent ITO (indium tin oxide) film is used for the hole injection electrode, and the electron injection electrode is made of a metal having a low work function and a low electron injection barrier, such as an MgAg alloy or an AlLi alloy proposed by Tang et al. An alloy with a metal having a large work function and being stable is often used. The electron injecting electrode may have a laminated structure of a layer that substantially contributes to the injection of electrons into the light emitting functional layer and a layer that has electrical conductivity as an electrode. For example, an electron injection electrode having a laminated structure of a lithium oxide layer and an aluminum layer is used. In this case, it is known that the driving voltage is reduced and the luminous efficiency is improved as compared with the case where only the aluminum layer is used for the electron injection electrode.

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 variously 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. As the hole injection electrode of the present invention, in addition to these ordinary ITO films, a coated film of a transparent conductive paint 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 metals with low work function and low electron injection barrier and metals with relatively high work function and stable, and also compare Al film after forming thin LiF film or Al ₂ O ₃ film Laminated electrodes having various thicknesses and various other electrode configurations can be used.
An electrode having a relatively thick Al film formed on the i-layer exhibits excellent characteristics during pulse driving.

In the first invention of the present application, the essential part is a unique hole transporting material having an asymmetric pentaphenyldiamine moiety and an α-phenylstyryl moiety as represented by the general formula (1). The use of this material makes it possible to stably realize a light-emitting device having a high efficiency and a long life, which cannot be achieved with various conventional symmetric hole transport materials. In particular, compounds having a substituent as exemplified in some of the present application have extremely high efficiency and long life. As the layer structure and the light emitting material, generally known materials can be widely used.

In the seventh invention of the present application, the main part is a unique hole transporting material having an asymmetric triphenylamine moiety and α-phenylstilbene moiety as represented by the general formula (2). The use of this material makes it possible to stably realize a light-emitting device having a high efficiency and a long life, which cannot be achieved with various conventional symmetric hole transport materials. In particular, compounds having a substituent as exemplified in some of the present application have extremely high efficiency and long life. As the layer structure and the light emitting material, generally known materials can be widely used.

In the sixteenth invention of the present application, the main components are a triphenylamine tetramer compound represented by the general formula (Chemical Formula 3) and a general formula (Chemical Formula 4) as a hole transport material. The composition contains a diphenylamino-α-phenylstilbene compound represented by the formula and a hole transporting material having a smaller ionization potential than either of them, and at least three kinds of such hole transporting materials are used. As a result, a highly efficient and long-life light-emitting device that cannot be achieved by various conventional hole transport materials can be stably realized. In particular, as described in the related art, when realizing a display using a passive matrix, a large instantaneous luminance is required by pulse driving. However, the present invention makes it possible to significantly suppress the driving voltage, thereby achieving power consumption efficiency. In addition to the improvement in the life, it is possible to realize a longer life and higher reliability. As other layer configurations and light emitting materials, generally known materials can be widely used.

In the twenty-third invention of the present application, the essential part has an original structure in which an ultra-thin metallic lithium film and an aluminum film are laminated as an electron injection electrode, and other layer constitutions and materials constituting each layer are generally known. Can be widely used.

In the twenty-eighth to thirty-first aspects of the present invention, the essential part is that the light emitting functional layer has a specific thin film shape, and a coating type medium resistance conductive layer is provided between the hole injection electrode and the light emitting functional layer. That is, generally known materials can be widely used for other layer constitutions and materials constituting each layer.

Here, if the resistivity of the conductive layer is too high, the driving voltage becomes high, and if it is too low, the insulating property between adjacent elements deteriorates. In particular, when the thin film EL elements of the present invention are arranged in a matrix to display image information, it is necessary to ensure sufficient insulation between adjacent elements. However, even with such a matrix image display member, the distance between pixels is sufficiently large compared to the thickness of the medium-resistance conductive layer. Therefore, good results can be obtained by using a medium-resistance conductive layer having an appropriate volume resistivity. Can be obtained. Here, the appropriate volume resistivity refers to a resistivity in which the resistance in the thickness direction of the medium-resistance conductive layer is smaller than the resistance of the light emitting element itself, and the resistance between pixels is sufficiently larger than the resistance of the element. The specific resistivity depends on the distance between pixels, panel size, arrangement, and the like. For example, assuming a panel having a pixel size of 70 μm × 210 μm, a distance between pixels of 20 μm, and a column length of 50 mm, the light-emitting characteristics of a thin film EL element forming each pixel are 1 A / cm ² at 3000 V and 3000 A.
0 cd / m ² , the element resistance of each pixel is about 60
kΩ. If the thickness of the medium resistance conductive layer is 50 nm,
When the volume resistivity is 10 ⁶ Ωcm or more, more than half of the drive voltage is applied to the medium-resistance conductive layer, and at least 10 ⁶
Ωcm or less, desirably 10 ⁵ Ωcm or less. Resistance between adjacent pixels (resistance between columns)
Is, 10 ³ [Omega] cm in the following will be the pixel current equal to the column between the leakage current flows when the potential difference between the adjacent columns, at least 10 ³ [Omega] cm or more, preferably 10 ⁴
It needs to be Ωcm or more. That is, the medium resistance conductive layer of the present invention has a thickness of 10 ⁴ to 10 ⁵ Ωc
Refers to a conductive layer having a resistivity of about m.

As the material constituting the medium resistance conductive layer, generally known conductive polymers such as polypyrrole, polythiophene, and polyaniline, or those obtained by combining them with an appropriate dopant can be used widely.

Preferably, the ionization potential is
Compared with the ionization potential of the hole transporting material used in the light emitting functional layer, from 0.4 eV to 0.4 mm.
The range of 2 eV is preferable from the viewpoint of hole injection efficiency.

Here, the period of the unevenness in the in-plane direction refers to the average distance from the hill to the hill or the valley to the valley measured in the in-plane direction of the substrate. The pixel cycle is a numerical value generally called a pixel pitch, and indicates a distance from one end of a pixel to the same end of an adjacent pixel. The average of the difference between the concave portion and the convex portion measured in the direction perpendicular to the substrate surface indicates the average value of the difference between the height of the convex portion vertex and the height of the adjacent concave portion vertex.

In the twenty-ninth aspect of the present invention, the boundary between the concave portion and the convex portion is defined as the positive or negative of the second derivative of the cross-sectional shape curve, that is, the polarization point.

The essence of the invention of the twenty-eighth to thirty-first aspects is to increase the ratio of light emitted from the light-emitting functional layer to the front side of the element on the transparent substrate side. An attempt to extract the emitted light forward as efficiently as possible by appropriately processing the shape of the substrate is disclosed in, for example, G.S. O by Gu et al.
pt. Lett. , Vol. 22, p. 396, (19
97). However, it is not practical from a cost standpoint to process the substrate into a shape that directly emits light as described in this report, and it is possible if the pixels are sufficiently large. Even so, there is a problem that is difficult in the case of fine pixels.

Then, the present inventors prepared substrates of various shapes with various etchant compositions and various temperatures by using a method capable of performing batch processing on the entire substrate surface such as etching. A hole injecting electrode and a medium resistance conductive layer were provided on the upper layer for investigation. From these studies, the present authors provided a coating-type medium-resistance conductive layer between the hole injection electrode and the light-emitting functional layer, and formed the light-emitting functional layer into the above-mentioned shape, thereby obtaining isotropic light emission. The inventors have found that significant efficiency can be improved by taking out most of the light in the horizontal direction on the substrate surface in the front direction of the substrate, and have completed the present invention.

More specifically, by making the average value W1 of the period of the in-plane unevenness smaller than the pixel period W2, the light emitted in the horizontal direction is scattered and extracted in the pixel, and By setting the average D1 of the difference between the concave portion and the convex portion measured in the direction perpendicular to the substrate surface to 以上 or more of the film thickness D2 of the light emitting functional layer, the light emitted in the lateral direction is not scattered. The depth or height of the unevenness is compared with the period by suppressing propagation to the outside of the pixel, and setting the ratio W1 / D1 of W1 to D1 to 10 or more and D1 to W2 or less. By improving the microscopic flatness, the forward reflection efficiency of light emission can be improved and the efficiency can be maximized.

When D1 is not more than 1/2 of D2, the effect of improving the luminous efficiency is small, and preferably 1 or more is used.

If the ratio W1 / D1 of W1 to D1 is less than 10, the flatness is not sufficiently seen microscopically, and sufficient reflection in the forward direction cannot be expected. In addition, in such a shape, in general, sufficient electric conduction of the thin film transparent hole injection layer cannot be obtained, and uniform light emission is often hindered. So W1 / D1 is 10
The number is preferably 20 or more.

Further, by providing the coating type medium resistance conductive layer, it is possible to realize a non-smoothness macroscopically represented by the above-mentioned form, and at the same time, a more microscopically smooth interface. This is obtained by the surface tension of the paint at the time of forming the coating type medium resistance conductive layer.

In the thirty-second aspect of the present invention, the essential part is that buckminsterfullerene C60 or C70 is used for a hole transporting layer which is laminated with an electron transporting light emitting layer to form a light emitting functional layer. As a material for forming each layer, generally known materials can be widely used.

It is known that buckminsterfullerene can obtain extremely high hole mobility, and it has been reported that a highly sensitive photoreceptor is obtained by dissolving it in the coating material of the hole transport layer of an organic photoreceptor. However, as a result of intensive studies on the application to a thin film EL device, the use of a vapor-deposited film of buckminsterfullerene as a hole transport layer has excellent heat resistance, high reliability, long life, and high efficiency. The inventors have found that an EL light-emitting element can be obtained, and have completed the present invention. In particular, due to its excellent hole transporting ability, driving at an extremely low voltage can be realized even when pulse driving is performed in a simple matrix panel driven at high duty. It is considered that the suppression of the driving voltage not only improved the luminous efficiency of the device but also achieved high reliability and long life.

In the thirty-third aspect of the present invention, the essential part is that buckminsterfullerene C60 or C70 is used for an electron transporting layer which is laminated with a hole transporting light emitting layer to form a light emitting functional layer. As a material for forming each layer, generally known materials can be widely used.

It is known that buckminsterfullerene can obtain an extremely high hole mobility, and an extremely high electron mobility is reported. The authors are thin film EL
As a result of diligent studies of application to the device, using a deposited film of buckminsterfullerene as an electron transport layer and combining it with a light emitting layer having a hole transporting property to form a light emitting functional layer having a laminated structure, it has excellent heat resistance and high heat resistance. The inventors have found that a highly reliable EL device having a long life and high efficiency can be obtained, and have completed the present invention. In general, compounds that have a small concentration quenching even in a solid thin film and can be used as a light-emitting material are rich in materials having excellent hole-transport properties rather than those having excellent electron-transport properties. It can be easily designed. In addition, due to the high electron mobility of the electron transport layer, even when pulse driving is performed in a simple matrix panel driven at high duty, driving at an extremely low voltage can be realized. By suppressing this drive voltage,
As a result, it is considered that not only the luminous efficiency of the device was improved, but also high reliability and long life were achieved.

In the thirty-fourth aspect of the present invention, the essential part is that the light-emitting functional layer is formed of buckminsterfullerene C60 or C60.
70, a light-emitting layer, and an electron-transporting layer composed of a deposited film of Buckminsterfullerene C60 or C70. The other layer constitution and the material constituting each layer are as follows. Generally known materials can be widely used.

It is known that buckminsterfullerene can obtain an extremely high hole mobility, and an extremely high electron mobility is reported. The authors are thin film EL
As a result of diligent study of application to the device, by forming a thin-film light-emitting layer as a light-emitting functional layer with a laminated structure sandwiched by a deposited film of buckminsterfullerene, it has excellent heat resistance,
The inventors have found that a highly reliable, long-life, and highly efficient EL light-emitting element can be obtained, and have completed the present invention. In general, there are few compounds that can be used as a light-emitting material with a small concentration quenching even in a solid thin film, and there are not many materials that are sufficiently excellent in charge transfer ability, but buckminsterfullerene is used for a hole transport layer and an electron transport layer, By using a thin film of a material having excellent light-emitting ability for the light-emitting layer, it is possible to easily design devices of various luminescent colors with high efficiency. In addition, due to the charge transport layer having high charge transfer ability, driving at an extremely low voltage can be realized even when pulse driving is performed in a simple matrix panel of high duty driving. It is considered that the suppression of the driving voltage not only improved the luminous efficiency of the device but also achieved high reliability and long life.

Here, the deposited film of buckminsterfullerene does not necessarily have to be used alone, but can be formed by a method such as co-evaporation with an organic hole transport material or an organic electron transport material at an appropriate ratio.

In the thirty-fifth aspect of the present invention, the essential part is that carbon nanotubes are used for a hole transport layer which is laminated with an electron transporting light emitting layer to form a light emitting functional layer. As the material to be used, generally known materials can be widely used.

The hole transport layer does not need to be entirely composed of carbon nanotubes, and its content may be at least 10% by weight, preferably at least 50%.
More preferably, it is at least 70%. The authors are thin film EL
As a result of diligent study of application to the device, using a coating containing carbon nanotubes in the above ratio as a concentration in the total solid content, and using it as a hole transport layer formed by coating, it has excellent heat resistance and high reliability. The present inventors have found that a highly efficient, long-life, high-efficiency EL light-emitting element can be obtained, and have completed the present invention. In particular, even when pulse driving is performed in a simple matrix panel of high duty driving, driving at an extremely low voltage can be realized. It is considered that the suppression of the driving voltage not only improved the luminous efficiency of the device but also achieved high reliability and long life.

Here, carbon nanotubes obtained by a generally known synthesis method such as a discharge method or an electron beam irradiation method can be used. Further, since the carbon nanotubes are unnecessary in the solvent for forming the coating, the carbon nanotubes form the hole transport layer from the state of being dispersed in the coating. It is desirable from the viewpoint of adhesiveness to form a paint together with a hole transporting polymer such as polyvinyl carbazole and obtain a hole transporting layer as a resin dispersion film.

In the thirty-sixth aspect of the present invention, the essential part is that carbon nanotubes are used for an electron transporting layer which is laminated with a hole transporting light emitting layer to form a light emitting functional layer. As the material to be used, generally known materials can be widely used.

The electron transport layer does not need to be entirely composed of carbon nanotubes, and its content may be at least 10% by weight, preferably at least 50%.
More preferably, it is at least 70%. The authors are thin film EL
As a result of diligent study of application to the device, using a paint containing carbon nanotubes in the above ratio as a concentration in the total solid content, and using it as an electron transport layer formed by coating, it has excellent heat resistance and high reliability Thus, they have found that a long-life, high-efficiency EL light-emitting element can be obtained, and have completed the present invention. In particular, even when pulse driving is performed in a simple matrix panel of high duty driving, driving at an extremely low voltage can be realized. It is considered that the suppression of the driving voltage not only improved the luminous efficiency of the device but also achieved high reliability and long life.

Here, carbon nanotubes obtained by a generally known synthesis method such as a discharge method or an electron beam irradiation method can be used. Further, since the carbon nanotubes are unnecessary in the solvent for forming the coating, the carbon nanotubes form the hole transport layer from the state of being dispersed in the coating. It is desirable from the viewpoint of adhesiveness to form a coating with the resin and obtain the electron transport layer as a resin dispersion film. Various electron transporting substances may be dissolved or dispersed at the same time to form a mixed layer.

In the thirty-seventh aspect of the present invention, the essential part is that the hole transport layer contains an organic polysilane having a number average molecular weight of 10,000 or more, and other layer constitutions and materials constituting each layer are generally known. The material can be widely used. In the thirty-seventh invention of the present application,
It refers to a content that contributes to the charge transport, and does not mean a very small addition, and naturally includes a hole transport layer composed of itself.

In particular, when the thin film shape of the light emitting function layer is the specific shape as described above, the efficiency of forward emission of light can be improved and the efficiency can be maximized. Here, the coating film of the organic polysilane has a macroscopic non-smoothness due to the surface tension of the coating material, and at the same time, can realize a more microscopically smooth interface.

According to the thirty-ninth aspect of the present invention, the essential part is that the light emitting functional layer is composed of a hole transporting light emitting layer and an n-type amorphous silicon layer, and other layer constitutions and materials constituting each layer are generally Known materials can be widely used.

In particular, when the thickness of the n-type amorphous silicon layer is 50 nm or more and 250 nm or less, high efficiency and reliability can be obtained. If the film thickness is 50 nm or less, a good amorphous silicon film cannot be obtained, and the density of defect states at the interface with the electrode or the interface with the hole transporting light emitting layer cannot be suppressed sufficiently low, resulting in high light emission. I can't get efficiency. If the film thickness is 250 nm or more, a decrease in luminous efficiency due to light absorption cannot be ignored.

Here, the n-type amorphous silicon film can be formed by a method such as sputtering, laser ablation, optical CVD, or the like, in addition to a film formed by a normal plasma CVD method.

In the inventions of the forty-first and forty-third embodiments, the essential part is that the electron-transporting light-emitting layer comprises an electron-transporting host material
A phosphorescent material doped as a guest material, and the number of molecules of the phosphorescent material is 1/50 or more of the number of carriers injected into the device during one light emission period;
The thickness is not more than 0 times, and generally known materials can be widely used as other layer constitutions and materials constituting each layer. Other drive parameters can be designed as usual. Here, as the number of carriers to be injected, the smaller one of the number of electrons and holes injected into the device is used.

Here, one light emitting period refers to a light emitting time per individual pulse in pulse driving, and assuming a passive matrix panel having 640 pixels in width and 480 pixels in height and divided into upper and lower parts by driving, the driving duty is Is 1/24
0, the frame rate is 60 Hz, and one light emission period is 69
μs. Compared with the number of carriers injected per unit area during this one light emission period, the number of molecules of the phosphorescent material contained in the thin film EL element per unit area is 1 /
When the ratio is 50 or more and 10 times or less, a highly efficient light-emitting panel can be realized even with a phosphorescent material which is generally said to have a low light emission transition probability.

This is because the emission transition probability of a phosphorescent substance is generally low, it takes a long time to emit light from an excited state and return to a ground state, and even when carriers are continuously injected or pulse driving is performed. If the amount of carriers injected during one emission period is too large compared to the number of molecules of the phosphorescent material, high efficiency can be obtained because many carriers cannot contribute to the excitation of the phosphorescent material. Absent.

As a result of intensive studies on the relationship between the light emission period and the concentration of the phosphorescent material, the present inventors have found that a remarkably high efficiency can be obtained when the above relationship is satisfied, thereby completing the present invention.

Specifically, in order to obtain an average luminance of 270 cd / m ² at a frame rate of 60 Hz and a duty of 1/240, if the aperture ratio is 60%, the peak luminance is 10800.
0 cd / m ^{2 is} required, the peak current is 10800 A / m ² if the efficiency is 10 cd / A, and 5 × 10 18 carriers / m ² must be injected during one light emitting period when the light emitting time is applied. is there. On the other hand, when the electron transporting host material is Al
If q ₃ and the film thickness are 50 nm, the number of host molecules is approximately 1
It becomes 0 ²⁰ pieces / m ² . That is, in this case, at a doping concentration of 0.1% or more and 50% or less in molar concentration,
Significantly higher efficiencies are obtained. On the other hand, as is generally known, when a host material is doped with a light emitting material as a guest material, an efficiency reduction called concentration quenching is recognized unless the concentration is sufficiently low. That is, in practicing the present invention, in order to avoid such a decrease in efficiency, the doping concentration is preferably designed to be at least 10 mol% or less, preferably several mol% or less. These designs differ depending on the molecular weight, specific gravity, etc. of the material,
It is optimized mainly by the film thickness (the film thickness of the guest material doped region), the frame rate, and the duty ratio. That is, the driving method of the present invention can be described as a driving method that satisfies the above relationship.

In the inventions of the forty-second and forty-fourth aspects, the essential part is that the hole-transporting light-emitting layer comprises a hole-transporting host material,
A phosphorescent material doped as a guest material, and the number of molecules of the phosphorescent material is 1/50 or more of the number of carriers injected into the device during one light emission period;
The thickness is not more than 0 times, and generally known materials can be widely used as other layer constitutions and materials constituting each layer. Other drive parameters can be designed as usual.

Next, a more detailed description will be given based on specific examples.

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 Corporation, size 100 × 100 mm × t =
0.7 mm, sheet resistance of about 14 Ω / □), and the emission area is 1.4 × 1.4 mm due to overlap with the electron injection electrode.
It was patterned by photolithography so that Substrate treatment after photolithography is performed by immersing in a commercially available resist stripping solution (a mixed solution of dimethyl sulfoxide and N-methyl-2-pyrrolidone), stripping, rinsing with acetone, and immersing in fuming nitric acid for 1 minute. Then, the resist was completely removed. The surface of the ITO was sufficiently cleaned on both sides of the back surface of the substrate, and mechanically rubbed and cleaned with a nylon brush while sufficiently supplying a 0.238% aqueous solution of tetramethylammonium hydroxide. Then, it was sufficiently rinsed with pure water and spin-dried. Then, in a commercially available plasma reactor (PR41 type, manufactured by Yamato Scientific Co., Ltd.), an oxygen flow rate of 20 sccm,
Oxygen plasma treatment was performed for 1 minute under the conditions of a pressure of 0.2 Torr and a high-frequency output of 300 W, and then placed in a vapor deposition tank.

As the vacuum evaporation apparatus, an apparatus obtained by modifying a commercially available high vacuum evaporation apparatus (model EBV-6DA, manufactured by Japan Vacuum Engineering Co., Ltd.) was used. 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
[4- (2,2) on the glass substrate
2-Diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4-methoxyphenyl) phenylamino] phenyl} amine was formed at a deposition rate of 0.3 nm / s to a film thickness of about 80 nm.

Here, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4
[-Methoxyphenyl) phenylamino] phenyl diamine was synthesized and obtained as follows.

In a 300 ml four-necked flask, 27.6 g of N, N'-diphenyl-p-phenylenediamine, 50 g of p-iodoanisole, 75 ml of nitrobenzene, K ₂
30 g of CO ₃ , 7.2 g of copper powder and I ₂ (trace) were added, and the mixture was gently refluxed for 24 hours with stirring while distilling off the generated water. After that, steam distillation was performed. When no distillate was generated, the residue was cooled and the residue was extracted with toluene. After the toluene is distilled off, alumina column chromatography is performed using a toluene solvent. After distilling off toluene, recrystallization was performed with a toluene: ethanol (1: 3) solvent, and 35.3 g of N, N′-diphenyl-N,
N′-bis (p-methoxyphenyl) -p-phenylenediamine was obtained. mp = 132-4 [deg.] C.

Then, in a 200 ml four-necked flask, 20.4 g of POCl 3 was added at 25 ° C. in a mixture of 20.4 g of N-methylformanilide and 17 ml of o-dichlorobenzene.
(12 ml) is added dropwise over 1 hour. Thereafter, 35 g of N, N′-diphenyl-N, N′-bis (p-methoxyphenyl) -p-phenylenediamine obtained above was added,
Stirring is further continued at 90-95 ° C for 2 hours. Cooled after the reaction, poured into 10% -H ₂ SO ₄ 70ml, toluene extraction. The toluene solution was washed successively with water, 5% -Na ₂ CO ₃ and water, and dried over Na ₂ SO ₄ . After toluene is distilled off, silica column chromatography is performed using a toluene solvent. After distilling off the toluene,
Recrystallized with ethanol. 16.9 g of orange crystals, p-
[N- (p-methoxyphenyl) -N- {pN'-phenyl-N '-(p-methoxyphenyl) aminophenyl}]-aminobenzaldehyde was obtained. mp = 160
-1 ° C.

Next, 9.9 was added to a 200 ml three-neck flask with diethyl-1,1-diphenylmethylphosphonate.
g, p- [N- (p-methoxyphenyl)-obtained above.
N- {p-N'-phenyl-N '-(p-methoxyphenyl) aminophenyl}]-aminobenzaldehyde 1
Dissolve 6.4 g in dry DMF (65 ml) and add t-BuOK
4.4 g are added at 21-33 ° C over 30 minutes. Thereafter, stirring is continued at 20 to 25 ° C. for 3.5 hours. Then, pour into 300 ml of ice water while stirring. After extracting with toluene, washing with water and distilling off toluene, alumina column chromatography was performed using a toluene solvent to obtain 0.7 g of [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4.
-[(4-Methoxyphenyl) phenylamino] phenyl diamine was obtained. mp = 271-2 [deg.] C.

Next, tris (8
-Quinolinolato) aluminum (manufactured by Dojin Chemical Co., Ltd.)
Was formed to a film thickness of about 50 nm at a deposition rate of 0.3 nm / s.

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 thin-film EL device thus prepared is
After the inside of the vapor deposition tank was leaked with dry nitrogen, a lid made of Corning 7059 glass was attached with an adhesive (manufactured by Anelva Co., trade name: Super Back Seal 953-7) under a dry nitrogen atmosphere.
000) to make a sample.

The thin-film EL element samples thus obtained were evaluated as follows.

The initial evaluation was carried out in a normal laboratory environment at room temperature and normal humidity 12 hours after the glass lid was adhered after the deposition of the device, and the luminous efficiency (cd / A) and the driving voltage at the time of light emission of 500 cd / m ² were obtained. Was 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 time when the luminance reached half (250 cd / m ² ) was evaluated as the life.

As a DC drive power source, a DC constant current power source (manufactured by Advantest Co., Ltd., product name: Multi-channel current voltage controller TR6163) is used to measure the voltage-current characteristics, and the luminance is measured by a luminance meter (manufactured by Tokyo Optical Machinery Co., Ltd.) Name Topcon Luminescence Meter B
M-8). Luminance image quality such as uneven brightness and black spots (non-light-emitting portions) was observed with a 50-fold optical microscope.

The pulse drive uses a self-made constant current pulse drive circuit, the pulse cycle is 100 Hz (10 ms), the duty is 1/240 (pulse width 42 μs), the pulse waveform is a square wave, and the pulse current value is set to various values. Was evaluated. The luminance was measured by a luminance meter (trade name: Topcon Luminescence Meter BM-8, manufactured by Tokyo Optical Machine Co., Ltd.), and the pulse drive voltage when the average luminance was 270 cd / m ² was evaluated. The initial luminance is 270 cd / m
^At a pulse voltage value of ² , continuous pulse driving was performed in a normal laboratory environment at normal temperature and normal humidity to perform a continuous light emission test. From this test, the time when the luminance reached half (135 cd / m ² ) was evaluated.

The results of these evaluations are shown in (Table 1).

[0132]

[Table 1]

According to this embodiment, high luminous efficiency is obtained,
Light emission with excellent visibility is obtained by self-emission at low drive voltage,
Even in the continuous light emission test, a thin-film EL element which has a small decrease in luminance, has no problems such as black spots and luminance unevenness, and can be used stably for an extremely long period of time was realized.

In particular, even at the time of pulse driving corresponding to the driving of an actual panel, the driving voltage is high and the driving voltage is low, the brightness is small even in the continuous light emission test, there is no problem such as black spots and uneven brightness, and the operation is performed for an extremely long time. A thin-film EL element that can be used stably was realized.

Example 2 In the formation of the hole transporting layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl [4- (2,2-diphenylvinyl) phenyl] instead of [amino] phenyl} amine
A thin film EL device sample was prepared in the same manner as in Example 1 except that [4- (diphenylamino) phenyl] phenylamine was used, and evaluation was performed as described in Example 1.

Table 1 shows the results.

Example 3 In the formation of the hole transporting layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) @ 4-[(4-methoxyphenyl) phenyl [4- (2,2-diphenylvinyl) phenyl] instead of [amino] phenyl} amine
A thin film EL device sample was prepared in the same manner as in Example 1 except that (4-t-butylphenyl) {4-[(4-t-butylphenyl) phenylamino] phenyl} amine was used. Evaluation was performed as described.

Table 1 shows the results.

Example 4 In the formation of the hole transporting layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl [4- (2,2-diphenylvinyl) phenyl] instead of [amino] phenyl} amine
A thin film EL device sample was prepared in the same manner as in Example 1 except that (2-methoxyphenyl) {4-[(2-methoxyphenyl) phenylamino] phenyl} amine was used. An evaluation was performed.

Table 1 shows the results.

Example 5 In the formation of the hole transporting layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl [4- (2,2-diphenylvinyl) phenyl] instead of [amino] phenyl} amine
A thin film EL device sample was prepared in the same manner as in Example 1 except that (2,3-dimethoxyphenyl) {4-[(2,3-dimethoxyphenyl) phenylamino] phenyl} amine was used. Evaluation was performed as described.

The results are shown in (Table 1).

(Example 6) In the formation of the hole transport layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl A thin film EL device sample was prepared in the same manner as in Example 1 except that {4- [4- (2,2-diphenylvinyl) phenyl] phenyl} diphenylamine was used instead of [amino] phenyl} amine.

Here, {4- [4- (2,2-diphenylvinyl) phenyl] phenyl} diphenylamine was obtained by synthesizing as follows.

92.4 g of biphenyl and 420 ml of AcOH are placed in a 1000 ml four-necked flask, and water is added at 80 ° C. until the solution becomes turbid (about 90 ml). Then _{conc-H 2 SO 4 18ml,} 2 61.2g, iodate 24 g, the CCl ₄ 48 ml was added, stirred vigorously until the color of iodine disappeared (about 3 hours). After that the liquid temperature is 60 ℃
After lowering to a degree, pour into 1800 ml of water while stirring. The crystals are separated by filtration, washed with water and dried. Distillation under reduced pressure (bp5: 160-180 ° C) in an oil bath, 113.2 g
Of p-iodobiphenyl was obtained.

Next, 27 g of diphenylamine and p-iodobiphenyl 4 obtained above were placed in a 300 ml four-necked flask.
5 g, 100 ml of nitrobenzene, 45 g of K ₂ CO ₃ , 10.8 g of copper powder, and I ₂ (trace) were added, and the mixture was refluxed gently for 24 hours with stirring while distilling off the generated water. After that, steam distillation was carried out. When no distillate was generated, the residue was cooled and washed with water until the residue (harz) was neutralized (harz solidified).
After extracting with toluene and distilling off toluene, alumina column chromatography is performed with a small amount of a toluene solvent. After distilling off toluene, the residue was recrystallized with ethanol containing toluene to obtain 48.3 g of diphenylbiphenylamine. mp = 105-6
° C.

[0147] Next, N-neck was placed in a 200 ml four-necked flask.
36 g of methylformanilide, o-dichlorobenzene 3
21 ml of POCl3 in a mixture of 0 ml at 25 ° C.
Drops take time. Thereafter, 42 g of the diphenylbiphenylamine obtained above is added, and stirring is further continued at 90 to 95 ° C. for 2 hours. After the reaction was cooled, 10% -H ₂ SO ₄ 70
Then, the mixture was poured into the resulting mixture and extracted with toluene. The toluene solution is water,
5% -Na ₂ CO _3, successively washed with water, and dried over Na ₂ SO _4. After distilling off toluene, silica column chromatography was performed with a toluene solvent. After the toluene was distilled off, the residue was recrystallized from ethanol to obtain 24.6 g of 4- (4) as pale yellow crystals.
-N, N-diphenylaminophenyl) benzaldehyde was obtained. mp = 124.5-5.5 [deg.] C.

Then, in a 200 ml three-necked flask, diethyl-1,1-diphenylmethylphosphonate 21.4 was added.
g, 24.5 g of 4- (4-N, N-diphenylaminophenyl) benzaldehyde obtained above in dry DMF13
0 ml and dissolve 9.4 g of t-BuOK at 21-33 ° C.
It takes 1 hour to add. Thereafter, stirring is continued at 20 to 25 ° C. for 4 hours. Then, pour into 300 ml of ice water while stirring. After extracting with toluene, washing with water and distilling off toluene, alumina column chromatography is performed using a toluene solvent. After distilling off the solvent, the residue was dissolved in AcOEt, and then ethanol was added for crystallization, followed by suction filtration, and 15 g of {4- [4- (2,2-
[Diphenylvinyl) phenyl] phenyl} diphenylamine was obtained. mp = 142.5-3.5 [deg.] C.

The samples prepared as described above using the materials synthesized as described above were evaluated as described in Example 1.

Table 1 shows the results.

(Example 7) In the formation of the hole transport layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl A thin film was prepared in the same manner as in Example 1 except that {4- [4- (2,2-diphenylvinyl) phenyl] phenyl} bis (2,3-dimethoxyphenyl) amine was used instead of [amino] phenyl} amine. An EL element sample was prepared and evaluated as described in Example 1.

The results are shown in (Table 1).

Example 8 In the formation of the hole transporting layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl Except that {4- [4- (2,2-diphenylvinyl) phenyl] phenyl} di (2H-benzo [d] 1,3-dioxolan-4-yl) amine was used in place of amino] phenyl} amine In the same manner as in Example 1, a thin film EL element sample was prepared and evaluated as described in Example 1.

The results are shown in (Table 1).

Example 9 In the formation of the hole transporting layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl A thin film was prepared in the same manner as in Example 1 except that {4- [4- (2,2-diphenylvinyl) phenyl] phenyl} bis (4-t-butylphenyl) amine was used instead of [amino] phenyl} amine. An EL element sample was prepared and evaluated as described in Example 1.

The results are shown in (Table 1).

(Example 10) In the formation of the hole transport layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl Instead of [amino] phenyl} amine, {4- [4- (2,2-diphenylvinyl) -2]
-Methylphenyl] -3-methylphenyl} bis (3-
A thin-film EL device sample was prepared in the same manner as in Example 1 except that t-butylphenyl) amine was used, and was evaluated as described in Example 1.

The results are shown in (Table 1).

(Example 11) In the formation of the hole transport layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl Amino] phenyl} amine, N, N′-bis (4′-diphenylamino-4-
Biphenylyl) -N, N'-diphenylbenzidine at 0.3 nm / s, 4-N, N-diphenylamino-α-
Phenylstilbene at 0.01 nm / s, 4-N, N-
A thin film EL device sample was prepared in the same manner as in Example 1 except that bis (4-methylphenyl) amino-α-phenylstilbene was co-evaporated at a rate of 0.01 nm / s. An evaluation was performed.

Table 1 shows the results.

(Example 12) In the formation of the hole transporting layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl Instead of [amino] phenyl} amine, N, N′-bis (α-naphthyl) -N, N′-diphenylbenzidine was deposited at a rate of 0.3 nm / s,
A hole transport layer having a thickness of 80 nm was obtained.

In forming the electron injecting electrode, phenyl lithium (manufactured by Kanto Chemical Co., Ltd.) was formed as an electron injecting electrode at a rate of 0.1 nm / s to a thickness of 1 nm, and then aluminum (High Purity Chemical Co., Ltd.) was used. 1 nm /
The film was formed to a thickness of 100 nm at a speed of s to obtain a laminated electron injection electrode.

In all other respects, thin film EL device samples were prepared in the same manner as in Example 1 and evaluated as described in Example 1.

Table 1 shows the results.

(Example 13) A commercially available ITO used in Example 1 as a substrate having a hole injection electrode formed on a transparent substrate was used.
With glass substrate (manufactured by Sanyo Vacuum Corporation, size 100 ×
100 mm × t = 0.7 mm, sheet resistance about 14Ω /
Instead of □), an ITO film was formed by sputtering using a glass substrate whose surface shape was processed by etching. The ITO film was formed to a thickness of 200 nm, and the sheet resistance obtained a value of about 20 Ω / □.

A commercially available medium-resistance conductive polymer paint was applied to the above substrate by spin coating, and dried to form a film having a thickness of 50 nm. The shape of the surface of the medium resistance conductive layer is adjusted by the surface shape of the substrate by etching, the viscosity adjustment of the conductive polymer paint, and the application conditions. W1 = 10 μm, D1 = 1
An 80 nm shape was obtained. The area of the concave portion was about three times the area of the convex portion.

In the formation of the hole transport layer, [4-
Instead of (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4-methoxyphenyl) phenylamino] phenyl} amine, N, N′-bis (α-naphthyl) -N, N′-diphenylbenzidine was evaporated at a rate of 0.3 nm / s to obtain a hole transport layer having a thickness of 80 nm.

In all other respects, a thin film EL device sample was prepared in the same manner as in Example 1, and evaluation was performed as described in Example 1.

The results are shown in (Table 1).

(Example 14) In the formation of the hole transport layer in Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl Instead of [amino] phenyl} amine, Buckminsterfullerene C60 (Science Laboratories, purity 4N) was 0.3 nm / s,
0.3 n of N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine
A thin-film EL device sample was prepared in the same manner as in Example 1 except that m / s and 4-N, N-diphenylamino-α-phenylstilbene were co-evaporated at a rate of 0.01 nm / s. The evaluation was performed as described in the above section.

The results are shown in (Table 1).

(Example 15) Instead of the substrate in which the hole injection electrode was formed on the transparent substrate in Example 1, a commercially available ITO was used as the substrate in which the electron injection electrode was formed on the transparent substrate.
With glass substrate (manufactured by Sanyo Vacuum Corporation, size 100 ×
100 mm × t = 0.7 mm, sheet resistance about 14Ω /
Using □), patterning was performed by photolithography so that the emission area was 1.4 × 1.4 mm due to the overlap with the hole injection electrode.

Instead of the hole transporting layer formed on the transparent electrode, Bachminsterfullerene C60 (Science Laboratories, purity 4) was used as an electron transporting layer.
N) was co-evaporated at a deposition rate of 0.3 nm / s and tris (8-quinolinolato) aluminum (manufactured by Dojindo Co., Ltd.) at a deposition rate of 0.3 nm / s to form a film with a thickness of about 80 nm.

Next, instead of the electron transporting light emitting layer, 4,4′-bis (2,2-diphenyl-1-vinyl) -1,1′-biphenyl (DPVBi,
(Synthesized by the production method described in WO96 / 22273) to a film thickness of about 50 nm at an evaporation rate of 0.3 nm / s.

Next, as a hole injection electrode, platinum (Pt, manufactured by Kojundo Chemical Co., Ltd.) was formed to a film thickness of about 100 nm at a deposition rate of 1 nm / s.

In all other respects, thin film EL device samples were prepared in the same manner as in Example 1, and evaluations were made as described in Example 1.

Table 1 shows the results.

(Example 16) In the formation of the hole transporting layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl Instead of [amino] phenyl} amine, Buckminsterfullerene C60 (Science Laboratories, purity 4N) was 0.3 nm / s,
0.3 n of N, N'-bis (4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine
m / s, 4-N, N-diphenylamino-α-phenylstilbene was co-evaporated at a rate of 0.01 nm / s to obtain a hole transport layer having a thickness of 80 nm.

Next, the following light emitting layer and electron transport layer were formed in place of the electron transporting light emitting layer.

The light emitting layer was formed to a thickness of about 10 nm by co-evaporation of tris (8-quinolinolato) aluminum (manufactured by Dojin Chemical Co., Ltd.) at an evaporation rate of 0.3 nm / s.

The electron transport layer was made of Buckminsterfullerene C60 (Science Laboratories, purity 4).
N) was co-evaporated at a deposition rate of 0.3 nm / s and tris (8-quinolinolato) aluminum (manufactured by Dojindo Co., Ltd.) at a deposition rate of 0.3 nm / s to form a film having a thickness of about 50 nm.

A thin film EL device sample was prepared in the same manner as in Example 1 except for the above, and evaluation was performed as described in Example 1.

The results are shown in (Table 1).

(Example 17) In the formation of the hole transporting layer in Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl Instead of [amino] phenyl} amine, 2 parts by weight of carbon nanotubes (CNT, synthesized by an arc discharge method) and polyvinyl carbazole (PV
K) 1 part by weight and tetrahydrofuran (THF) 100
A thin-film EL element sample was prepared in the same manner as in Example 1 except that a hole transport layer in which carbon nanotubes were dispersed in polyvinyl carbazole was formed to a thickness of about 80 nm using a paint consisting of parts by weight. Evaluation was performed as described in 1.

The results are shown in (Table 1).

(Example 18) Instead of the substrate in which the hole injection electrode was formed on the transparent substrate in Example 1, a commercially available ITO was used as the substrate in which the electron injection electrode was formed on the transparent substrate.
With glass substrate (manufactured by Sanyo Vacuum Corporation, size 100 ×
100 mm × t = 0.7 mm, sheet resistance about 14Ω /
Using □), patterning was performed by photolithography so that the emission area was 1.4 × 1.4 mm due to the overlap with the hole injection electrode.

In place of the hole transport layer formed on the transparent electrode, a carbon nanotube (C
NT, synthesized by arc discharge method) Using an paint composed of 2 parts by weight, 1 part by weight of polyvinyl carbazole (PVK), and 100 parts by weight of tetrahydrofuran (THF), an electron transporting layer in which carbon nanotubes are dispersed in polyvinyl carbazole is used. The film was formed to a thickness of about 80 nm.

Next, instead of the electron transporting light emitting layer, 4,4′-bis (2,2-diphenyl-1-vinyl) -1,1′-biphenyl (DPVB) was used as a hole transporting light emitting layer.
i, synthesized by the production method described in WO 96/22273)
Was formed to a film thickness of about 50 nm at a deposition rate of 0.3 nm / s.

Next, as a hole injection electrode, platinum (Pt, manufactured by Kojundo Chemical Co., Ltd.) was formed at a deposition rate of 1 nm / s to a film thickness of about 100 nm.

In all other respects, a thin film EL device sample was prepared in the same manner as in Example 1, and the evaluation was performed as described in Example 1.

The results are shown in (Table 1).

Example 19 A commercially available ITO used in Example 1 as a substrate having a hole injection electrode formed on a transparent substrate was used.
With glass substrate (manufactured by Sanyo Vacuum Corporation, size 100 ×
100 mm × t = 0.7 mm, sheet resistance about 14Ω /
Instead of □), an ITO film was formed by sputtering using a glass substrate whose surface shape was processed by etching. The ITO film was formed to a thickness of 200 nm, and the sheet resistance obtained a value of about 20 Ω / □.

On the above substrate, [4-
Instead of (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4-methoxyphenyl) phenylamino] phenyl} amine, methylphenylpolysilane (MW = 30000, organic synthesis) by spin coating (Manufactured by Kagaku Co., Ltd.) from a toluene solution and dried to form a film having a thickness of 80 nm.

The shape of the surface of the hole transport layer is determined by adjusting the surface shape of the substrate by etching, adjusting the viscosity of the polysilane solution,
Adjusted according to coating conditions, W1 = 10 μm, D1 = 180
nm shape was obtained. The area of the concave portion is about 3 times the area of the convex portion.
It was twice.

In all other respects, thin film EL device samples were prepared in the same manner as in Example 1 and evaluated as described in Example 1.

The results are shown in (Table 1).

Example 20 In the formation of the hole transport layer of Example 19, methylphenylpolysilane (MW = 30) was used.
000, manufactured by Organic Synthetic Chemistry Co., Ltd.) was applied from a toluene solution.
(Science Laboratory Co., Ltd., purity 4N) 1 part by weight and methylphenylpolysilane (MW = 30000,
1 part by weight of Organic Synthetic Chemical Co., Ltd.) and 100 parts by weight of o-dichlorobenzene were applied from a coating material to form an organic thin film in the same manner as in Example 19 except that a hole transport layer having a thickness of 80 nm was formed. Example 1 was prepared by preparing an EL element sample.
The evaluation was performed as described in the above section.

The results are shown in (Table 1).

(Example 21) In the formation of the hole transport layer of Example 19, methylphenylpolysilane (MW = 30) was used.
000, manufactured by Organic Synthetic Chemical Co., Ltd.) from a toluene solution, 1 part by weight of carbon nanotubes (CNT, synthesized by an arc discharge method) and methylphenylpolysilane (MW = 30000, manufactured by Organic Synthetic Chemical Co., Ltd.) Parts by weight with tetrahydrofuran (THF) 10
An organic thin-film EL device sample was prepared in the same manner as in Example 19 except that a hole transport layer having a thickness of 80 nm was formed by applying a coating material mixed with 0 parts by weight, and evaluated as described in Example 1. went. The results are shown in (Table 1).

Example 22 In the formation of the electron transporting layer of Example 15, as the electron transporting layer, buckminsterfullerene C60 (Science Laboratories, purity 4N) and tris (8-quinolinolato) aluminum (Dohjin Chemical Co., Ltd.) were used. Example 15 except that an n-type amorphous silicon film (formed by a normal plasma CVD method using monosilane as a raw material) was formed to a film thickness of about 100 nm instead of the film thickness of about 80 nm. Then, a thin film EL element sample was prepared and evaluated as described in Example 1.

The results are shown in (Table 1).

Example 23 In the formation of the electron transporting layer of Example 15, as the electron transporting layer, buckminsterfullerene C60 (Science Laboratories, purity 4N) and tris (8-quinolinolato) aluminum (Dohjin Chemical Co., Ltd.) were used. Instead of forming a film of about 80 nm in thickness, an n-type amorphous silicon film (formed by a normal plasma CVD method using monosilane as a raw material) was formed to a thickness of about 100 nm.

Next, in forming the hole transporting light emitting layer,
4,4'-bis (2,2-diphenyl-1-vinyl)-
1,1′-biphenyl (DPVBi, WO96 / 222
73) at a deposition rate of 0.3 nm / s to a thickness of about 50 nm instead of N, N ′.
-Bis (α-naphthyl) -N, N′-diphenylbenzidine (manufactured by Kanto Chemical Co., Ltd.) at 0.3 nm / s, Cou
marin540 (C540, manufactured by Lambda Physique Co., Ltd.) was co-evaporated at a rate of 0.003 nm / s to form a hole-transporting light-emitting layer having a thickness of about 50 nm.

Otherwise, the procedure of Example 15 was repeated to form a thin film E.
An L element sample was prepared and evaluated as described in Example 1.

The results are shown in (Table 1).

(Example 24) In the formation of the hole transport layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl Amino] phenyl} amine, N, N′-bis (4′-diphenylamino-4-
Biphenylyl) -N, N'-diphenylbenzidine at 0.3 nm / s, 4-N, N-diphenylamino-α-
Phenylstilbene was co-evaporated at a rate of 0.01 nm / s to obtain a hole transport layer having a thickness of about 80 nm.

Next, tris (8-
Instead of forming (quinolinolato) aluminum (manufactured by Dojin Chemical Co., Ltd.) at a deposition rate of 0.3 nm / s to a film thickness of about 50 nm, tris (8-quinolinolato) aluminum (manufactured by Dojindo Co., Ltd.) is 0.3 nm / s. , 2,3
7,8,12,13,17,18-octaethyl-21
H-23H-porphine platinum (2) (PtOE
P, Porphyrin Products Co., Ltd.)
A thin-film EL element sample was prepared in the same manner as in Example 1 except that a 50 nm-thick electron transporting light-emitting layer was formed by co-evaporation at a rate of nm, and evaluation was performed as described in Example 1. .

The results are shown in (Table 1).

(Example 25) In the formation of the hole transporting layer of Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl Amino] phenyl} amine, N, N′-bis (4′-diphenylamino-4-
Biphenylyl) -N, N'-diphenylbenzidine at 0.3 nm / s, 4-N, N-diphenylamino-α-
Phenylstilbene was added at 0.01 nm / s, 2, 3, 7,
8,12,13,17,18-octaethyl-21H-
23H-porphine platinum (2) (PtOEP, manufactured by Porphyrin Products Co., Ltd.) was co-evaporated at a rate of 0.003 nm to obtain a hole-transporting luminescent layer having a thickness of about 50 nm in the same manner as in Example 1. Then, a thin film EL element sample was prepared and evaluated as described in Example 1.

The results are shown in (Table 1).

(Comparative Example 1) In the formation of the hole transport layer in Example 1, [4- (2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) ｛4-[(4-methoxyphenyl) phenyl Instead of [amino] phenyl} amine, N, N′-bis (α-naphthyl) -N, N′-diphenylbenzidine (manufactured by Kanto Chemical Co., Ltd.) is 0.3 nm.
A thin-film EL element sample was prepared in the same manner as in Example 1 except that the film was formed to a film thickness of about 80 nm at a rate of / s, and evaluation was performed as described in Example 1.

The results are shown in (Table 1).

(Comparative Example 2) In the formation of the stacked electron injection electrode of Comparative Example 1, only Li was added at a low temperature from an AlLi alloy (manufactured by Kojundo Chemical Co., Ltd., Al / Li weight ratio 99/1) to about 0.1%. A thin-film EL element sample was prepared in the same manner as in Example 1 except that the film was formed to a thickness of about 4 nm instead of forming the film to a thickness of about 1 nm at a deposition rate of 1 nm / s. An evaluation was performed.

The results are shown in (Table 1).

(Comparative Example 3) In forming the electron transporting layer of Example 15, as the electron transporting layer, Buckminsterfullerene C60 (Science Laboratories, purity 4N) and tris (8-quinolinolato) aluminum (Dojindo Chemical Co., Ltd.) were used. Thin film EL device in the same manner as in Example 15 except that only Tris (8-quinolinolato) aluminum (manufactured by Dojindo Co., Ltd.) was formed to a film thickness of about 80 nm instead of forming a film thickness of about 80 nm. Samples were prepared and evaluated as described in Example 1.

The results are shown in (Table 1).

(Comparative Example 4) In forming the electron transporting layer of Example 15, as the electron transporting layer, buckminsterfullerene C60 (Science Laboratories, purity 4N) and tris (8-quinolinolato) aluminum (Dojin Chemical Co., Ltd.) (Manufactured by Dojin Chemical Co., Ltd.) was formed to a film thickness of about 80 nm instead of forming a film having a thickness of about 80 nm.

Next, 4,4'-
Bis (2,2-diphenyl-1-vinyl) -1,1′-
Instead of biphenyl (DPVBi, synthesized by the production method described in WO96 / 22273), N, N'-bis (α
-Naphthyl) -N, N'-diphenylbenzidine (manufactured by Kanto Chemical Co., Ltd.) at 0.3 nm / s.
540 (C540, manufactured by Lambda Physique Co., Ltd.) at a rate of 0.003 nm / s.
Was formed.

Otherwise, the procedure of Example 15 was repeated to form a thin film E
An L element sample was prepared and evaluated as described in Example 1.

The results are shown in (Table 1).

(Comparative Example 5) In Comparative Example 1, tris (8-quinolinolato) aluminum (manufactured by Dojindo Co., Ltd.) was formed as an electron transporting light emitting layer at a deposition rate of 0.3 nm / s to a film thickness of about 50 nm. Instead, 4,4′-bis (2,2-diphenyl-1-vinyl) -1,1′-biphenyl (DPVBi, WO96) is used as a hole transporting light emitting layer.
/ 22273) by 0.3 nm
A thin film EL device sample was prepared in the same manner as in Comparative Example 1 except that the film was formed to a film thickness of about 50 nm at a deposition rate of / s, and evaluation was performed as described in Example 1.

The results are shown in (Table 1).

(Comparative Example 6) In Comparative Example 1, tris (8-quinolinolato) aluminum (manufactured by Dojindo Co., Ltd.) was formed as an electron transporting light emitting layer at a deposition rate of 0.3 nm / s to a film thickness of about 50 nm. Instead, tris (8-quinolinolato) aluminum (manufactured by Dojindo Co., Ltd.) is 0.3 nm / s, Coumarin 540 (C540,
Lambda Physique Co., Ltd.) was co-evaporated at a rate of 0.003 nm / s to form a thin film EL device sample in the same manner as in Comparative Example 1 except that an electron transporting light emitting layer having a film thickness of about 50 nm was formed. The evaluation was performed as described in Example 1.

The results are shown in (Table 1).

(Comparative Example 7) A thin film EL element sample was prepared in the same manner as in Example 24, and the evaluation of the pulse constant current drive was performed at a drive duty of 1/64 and a frame rate of 60 Hz.
The evaluation was performed as described in Example 1 except that the evaluation was performed.
The results are shown in (Table 1).

(Comparative Example 8) A thin-film EL element sample was prepared in the same manner as in Example 25, and the pulse constant current drive was evaluated by a drive duty of 1/64 and a frame rate of 60 Hz.
The evaluation was performed as described in Example 1 except that the evaluation was performed.

The results are shown in (Table 1).

[0228] device structure of Examples and Comparative Examples in Table 1 are abbreviated by abbreviations, Alq ₃ is
Tris (8-quinolinolato) aluminum, C540
Is Coumarin540, TPT is N, N'-bis (4'-diphenylamino-4-biphenylyl)-
N, N'-diphenylbenzidine, PS is 4-N, N
-Diphenylamino-α-phenylstilbene, NPD
Is N, N′-bis (α-naphthyl) -N, N′-diphenylbenzidine, 4-M2PPDA-PS is [4-
(2,2-diphenylvinyl) phenyl] (4-methoxyphenyl) {4-[(4-methoxyphenyl) phenylamino] phenyl} amine and PPDA-PS are [4
-(2,2-diphenylvinyl) phenyl] [4- (diphenylamino) phenyl] phenylamine, 4-Bu
2PPDA-PS is [4- (2,2-diphenylvinyl) phenyl] (4-t-butylphenyl) {4-
[(4-t-butylphenyl) phenylamino] phenyl diamine, 2-M2PPDA-PS is [4- (2,
2-diphenylvinyl) phenyl] (2-methoxyphenyl) {4-[(2-methoxyphenyl) phenylamino] phenyl} amine, 2,3-M2PPDA-PS
Is [4- (2,2-diphenylvinyl) phenyl]
(2,3-Dimethoxyphenyl) {4-[(2,3-dimethoxyphenyl) phenylamino] phenyl} amine, DPABiPS is {4- [4- (2,2-diphenylvinyl) phenyl] phenyl} diphenylamine,
2,3-M2DPABiPS is {4- [4- (2,2
-Diphenylvinyl) phenyl] phenyl} bis (2,
3-dimethoxyphenyl) amine, DO2DPABiP
S represents {4- [4- (2,2-diphenylvinyl) phenyl] phenyl} di (2H-benzo [d] 1,3-dioxolan-4-yl) amine, 4-Bu2DPABiP
S is {4- [4- (2,2-diphenylvinyl) phenyl] phenyl} bis (4-t-butylphenyl) amine, 4-Bu2DPA-2MP-3MPS is {4-
[4- (2,2-diphenylvinyl) -2-methylphenyl] -3-methylphenyl} bis (3-t-butylphenyl) amine, DPVBi is 4,4′-bis (2
2-diphenyl-1-vinyl) -1,1′-biphenyl, PtEOP is 2,3,7,8,12,13,1
7,18-octaethyl-21H-23H-porphine platinum (2), PVK is polyvinylcarbazole, C60 is buckminsterfullerene C60, C60
NT is a carbon nanotube, na-Si is n-type amorphous silicon, Al is aluminum, Li is lithium, PhLi is phenyllithium, Pt is platinum,
, And described in order from the ITO electrode side, separated by / as a symbol indicating the laminated configuration from the left. Numbers in parentheses indicate film thickness in nm, and + indicates co-evaporation.

[0229]

As described above, the thin film EL device according to the present invention and the method of driving the same have been described. However, the present invention relates to a hole injection electrode and an electron injection electrode, and at least the hole injection electrode and the electron injection A thin-film EL element having a light-emitting function layer provided between the electrode and the light-emitting layer, wherein the light-emitting function layer uses a specific material disclosed in the claims of the present application as a hole-transporting material, or By using the specific hole transport layer disclosed in the claims of the present application, or by using the specific electron injection electrode disclosed in the claims of the present application, or by using the specific electron transport disclosed in the claims of the present application. By using layers
Alternatively, by obtaining a specific light emitting functional layer shape by a specific element configuration disclosed in the claims of the present application, or by using a combination of the specific hole transport layer and the electron transport layer disclosed in the claims of the present application Having high luminous efficiency by using a specific phosphor content disclosed in the claims of the present application, or by a specific driving method disclosed in the claims of the present application,
It has no defects such as unevenness and black spots, emits light with excellent visibility by self-emission at a low driving voltage, has a small decrease in luminance even in a continuous light emission test, consumes little power, and can be used stably for an extremely long time This can realize a thin film EL element.

Also, even in the case of pulse driving corresponding to actual passive matrix panel driving, it has a low driving voltage, high efficiency and high reliability, can be used stably for an extremely long time with little power consumption. This can realize a thin film EL element.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toru Kawase 1006 Oaza Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Hitoshi Hisada 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Shinichi Mizuguchi 1006 Odaka Kazuma, Kadoma City, Osaka Pref. 1006 Kadoma, Kamon, Fumonma-shi Matsushita Electric Industrial Co., Ltd. F-term (reference) 3K007 AB03 AB06 AB11 AB17 DB03

Claims (8)

[Claims] 1. A thin-film EL device having a hole injection electrode, an electron injection electrode, and a light-emitting functional layer provided at least between the hole injection electrode and the electron injection electrode on a transparent substrate, The light emitting functional layer includes at least a layered structure of a hole transporting layer and an electron transporting light emitting layer, and the electron transporting light emitting layer is mainly composed of an electron transporting host material and a phosphorescent light emitting material doped as a guest substance. The number of molecules of the configured and doped phosphorescent material is １ ／ of the number of carriers injected into the device during one light emitting period.
A thin film EL device characterized by being at least 0 and at most 10 times. 2. A thin-film EL device having a hole injection electrode and an electron injection electrode on a transparent substrate and at least a light emitting function layer provided between the hole injection electrode and the electron injection electrode. The light emitting functional layer includes at least a laminated structure of an electron transporting layer and a hole transporting light emitting layer, and the hole transporting light emitting layer is mainly composed of a hole transporting host material and phosphorescent light doped as a guest substance. The number of molecules of the phosphorescent material that is made of a material and doped is 1/5 of the number of carriers injected into the device during one light emitting period.
A thin film EL device characterized by being at least 0 and at most 10 times. 3. A method for driving a thin-film EL device having a hole injection electrode and an electron injection electrode on a transparent substrate and at least a light-emitting functional layer provided between the hole injection electrode and the electron injection electrode. The light emitting functional layer includes at least a layered structure of a hole transport layer and an electron transporting light emitting layer, and the electron transporting light emitting layer is mainly composed of an electron transporting host material and phosphorescence doped as a guest substance. In a thin film EL device composed of a light emitting material, the number of carriers injected into the device during one light emitting period is
A method for driving a thin film EL element, wherein the number of molecules of the doped phosphorescent material is 1/10 or more and 50 times or less. 4. A method for driving a thin-film EL device having a hole injection electrode, an electron injection electrode, and a light emitting functional layer provided at least between the hole injection electrode and the electron injection electrode on a transparent substrate. The light emitting functional layer includes at least a laminated structure of an electron transporting layer and a hole transporting light emitting layer, and the hole transporting light emitting layer is mainly doped with a hole transporting host material and a guest substance. In a thin-film EL device composed of phosphorescent light-emitting materials, the number of carriers injected into the device during one emission period is
A method for driving a thin film EL element, wherein the number of molecules of the doped phosphorescent material is 1/10 or more and 50 times or less. 5. The thin film EL device according to claim 1, wherein the electron transporting light emitting layer is mainly composed of tris (8-quinolinolato) aluminum or a derivative thereof. 6. The thin film E according to claim 1, wherein the electron transporting light emitting layer is mainly composed of tris (4-methyl-8-quinolinolato) aluminum.
L element. 7. The method according to claim 3, wherein the electron transporting light emitting layer is mainly composed of tris (8-quinolinolato) aluminum or a derivative thereof. 8. The method according to claim 3, wherein the electron transporting light emitting layer is mainly made of tris (4-methyl-8-quinolinolato) aluminum.