JPH09249876A - Light emission element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a light emission element having high brightness, having high utilization efficiency of electric energy, improved in durability and useful for display elements, flat panel, etc., by including a specific compound in an element emitting light by electric energy. SOLUTION: An element having a substance controlling luminescence between positive electrode and negative electrode and emitting light by electric energy contains a compound represented by formula I [(n) is a natural number; X<1> and X<2> are each H, an alkyl, an aralkyl, an aryl, etc., Y is a single bond, an alkyl, an alkylene, a cycloalkyl, etc.; R<1> to R<8> are each H, an alkyl, an aralkyl, an aryl, an amine, a halogen nitro, cyano, etc.]. Furthermore, a compound of formula II (R<1> to R<22> are each H, an alkyl, an aralkyl, an aryl, a cycloalkyl, etc.) is most preferably used in the compound of formula I.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device capable of converting electric energy into light, such as a display device, a flat panel display, a backlight, a lighting, an interior, a sign, a signboard, an electrophotographic machine and an optical signal generator. The present invention relates to a light emitting device that can be used in the field of.

[0002]

2. Description of the Related Art In recent years, active research has been conducted on organic laminated thin-film light emitting devices that emit light when electrons injected from a negative electrode and holes injected from a positive electrode are recombined in an organic phosphor sandwiched between both electrodes. There is. This device is characterized by thinness, high-luminance light emission under a low driving voltage, and multicolor light emission by selecting a fluorescent material.

[0003] It is known from Kodak's C.I. W. Tang et al. (Appl. Phys. Lett. 51 (12)
21, p. 913, 1987). A typical structure of the organic laminated thin film light emitting device presented by Kodak is a hole transporting diamine compound and a light emitting layer on an ITO glass substrate.
-Hydroxyquinoline aluminum and Mg: Ag as a negative electrode were sequentially provided, and a green emission of 1000 cd / m 2 was possible with a driving voltage of about 10V.
In addition to the above-mentioned element components, there are some current organic laminated thin-film light emitting elements that have different configurations such as an electron transport layer, but basically follow the configuration of Kodak Corporation. .

Regarding the carrier transporting material in the organic laminated thin film element, a high carrier transporting ability is required to improve the luminous efficiency against electric power, and an appropriate electron quasi-concentration is required for confining excitons in the emitting layer and improving the carrier injection efficiency. The selection of material is effective. Further, it has been shown that it is also important not to form an exciplex at the interface with the light emitting layer in order to efficiently convert electric energy into light. Film thickness and film forming ability are also important requirements in actual device fabrication. The carrier transport material includes an electron transport material and a hole transport material.

Regarding the electron transport material, oxadiazole derivatives, 8-hydroxyquinoline aluminum and the like are specifically known, but there is not much knowledge and there is room for investigation.

On the other hand, active studies have been conducted on hole transport materials, and specifically, hydrazone compounds (JP-A-57-101844 and JP-A-58-15936) and stilbene compounds ( JP-A-57-14875
No. 0, JP-A-58-197043), triphenylamine compounds (JP-B-58-32372), oxadiazole derivatives (JP-B-34-1096).
6) and phthalocyanine derivatives (JP-A-57-51).
Heterocyclic compounds typified by JP No. 781).

[0007]

As described above, conventionally, in an organic laminated thin film light emitting device, it has a high carrier transport ability, a good film forming property, and thermal stability and electrochemical stability during light emission. A material having both properties has been desired. However, the carrier transporting ability is not sufficient, the heat resistance is low, and the turbulence of the interface is caused by crystallization.

It is an object of the present invention to solve the above problems and provide a highly durable element capable of emitting high brightness light even under a low voltage.

[0009]

In order to achieve the above object, the present invention is an element which emits light by electric energy when a substance controlling light emission exists between the positive electrode and the negative electrode, and the element has the following general formula: A light emitting device comprising a compound represented by (I).

[0010]

Embedded image (Here, n represents a natural number, X ¹ and X ² may be the same or different, and may be a hydrogen atom, an alkyl group,
It represents at least one kind of substituent selected from an aralkyl group, an aryl group and a cycloalkyl group. Y represents a single bond, an alkyl chain, an alkylene chain, a cycloalkyl chain, an aryl chain or an aralkyl chain. R ^{1 to} R ⁸ may be the same or different and each is a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a cycloalkyl group, a fluoroalkyl group, an amino group, a halogen, a nitro group, a cyano group, a hydroxyl group. And at least one kind of substituent selected from alkoxy groups. )

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The positive electrode of the present invention is a conductive metal oxide such as tin oxide, indium oxide or indium tin oxide (ITO), or gold, silver or chromium, as long as it is transparent for extracting light. Although not particularly limited, such as metals such as, inorganic conductive substances such as copper iodide and copper sulfide, and conductive polymers such as polythiophene, polypyrrole, polyaniline, etc., it is particularly preferable to use ITO glass or Nesa glass. The resistance of the transparent electrode is not limited as long as a current sufficient for light emission of the element can be supplied, but is preferably low from the viewpoint of power consumption of the element. For example, an ITO substrate of 300Ω / □ or less will function as an element electrode, but since it is now possible to supply a substrate of about 10Ω / □, use a substrate with a low resistance of 20Ω / □ or less. Is especially desirable. The thickness of ITO can be arbitrarily selected according to the resistance value, but normally 100
Often used between ~ 300 nm. Further, as the glass substrate, soda lime glass, non-alkali glass or the like is used, and the thickness only needs to be sufficient to maintain the mechanical strength.
As for the glass material, non-alkali glass is preferable because it is better to have less ions eluted from the glass,
Soda lime glass coated with a barrier such as SiO2 is also commercially available and can be used. The ITO film forming method is not particularly limited, such as an electron beam vapor deposition method, a sputtering method, and a chemical reaction method.

The negative electrode in the present invention is not particularly limited as long as it is a substance capable of efficiently injecting electrons or a substance (for example, an electron transport layer) adjacent to the substance that controls light emission (for example, an electron transport layer). Generally, platinum, gold, silver, copper, iron, tin, aluminum, indium, lithium, sodium, potassium,
Examples include calcium and magnesium. In order to increase the electron injection efficiency and improve the device characteristics, lithium, sodium, potassium, calcium, magnesium or an alloy containing these low work function metals is effective.
However, these low work function metals are generally unstable in the atmosphere, and platinum, gold, silver, and
It is preferable to stack metals such as copper, iron, tin, aluminum, and indium, alloys using these metals, inorganic substances such as silica and titania, and polymers such as polyvinyl alcohol and vinyl chloride. The method for producing these electrodes is not particularly limited as long as conduction can be established by resistance heating method vapor deposition, electron beam vapor deposition method, sputtering method, ion plating method, coating method or the like.

The structure of the substance that controls light emission in the present invention is as follows:
1) hole-transporting material / light-emitting material, 2) hole-transporting material / light-emitting material / electron-transporting material, 3) light-emitting material / electron-transporting material, and 4) a form in which the above combination substances are mixed in one layer,
Any of these may be used. That is, in addition to the multilayer laminated structure of 1) to 3) above, it is possible to provide a single layer of a light emitting material or a layer containing a light emitting material and a hole transport material and / or an electron transport material as in 4).

The hole-transporting material in the present invention contains a compound represented by the following general formula (I).

[0015]

Embedded image (Here, n represents a natural number, X ¹ and X ² may be the same or different, and may be a hydrogen atom, an alkyl group,
It represents at least one kind of substituent selected from an aralkyl group, an aryl group and a cycloalkyl group. Y represents a single bond, an alkyl chain, an alkylene chain, a cycloalkyl chain, an aryl chain or an aralkyl chain. R ^{1 to} R ⁸ may be the same or different and each is a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a cycloalkyl group, a fluoroalkyl group, an amino group, a halogen, a nitro group, a cyano group, a hydroxyl group. And at least one kind of substituent selected from alkoxy groups. )

When the compound represented by the above formula (I) used in the present invention is used in various vapor deposition methods and the like, if the molecular weight is too large, it may decompose without sublimation, so the molecular weight exceeds about 1000. It is desirable that n is not present, and n is preferably 5 or less, more preferably 3 or less. However, this is not the case when a film is formed by a coating method or the like.

In the compound represented by the above formula (I) used in the present invention, n is preferably 1-5, and X ¹ , X ²
In the description of, an alkyl group refers to a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, a propyl group and a butyl group, which is unsubstituted or substituted with an amino group, a hydroxyl group or an alkoxy group. It doesn't matter. Since the alkyl group does not directly participate in hole transport and improves the amorphous property of the molecule, it is preferable that the proportion of the alkyl group in the molecule is not so large, and C1 to C4 is preferable. Further, the aryl group refers to an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group, a terphenyl group, a pyrenyl group, etc., which is an alkyl group, an amino group, a hydroxyl group even if it is unsubstituted. Alternatively, it may be substituted with an alkoxy group or the like. Among aryl groups, those having strong conjugation are desirable, and therefore, a phenyl group, a naphthyl group, a phenanthryl group, a pyrenyl group and the like are preferable. Further, the aralkyl group refers to an aromatic hydrocarbon group via an aliphatic hydrocarbon such as a benzyl group or a phenylethyl group, and even if the aliphatic hydrocarbon and the aromatic hydrocarbon are both unsubstituted, an alkyl group, an amino group It may be substituted with a group, a hydroxyl group or an alkoxy group. The aliphatic hydrocarbon moiety in the aralkyl group is not directly involved in hole transport and therefore should not be too large, and is preferably C1 to C2. The aromatic hydrocarbon group in the aralkyl group is preferably one having strong conjugation, and therefore, a phenyl group, a naphthyl group, a phenanthryl group, a pyrenyl group and the like are preferable. In addition, the cycloalkyl group refers to a saturated alicyclic hydrocarbon group such as cyclopropyl, cyclopentyl, and cyclohexyl, which is unsubstituted or substituted with an alkyl group, an aryl group, an amino group, a hydroxyl group, an alkoxy group, or the like. It doesn't matter. Since the cycloalkyl group does not directly participate in hole transport and improves the amorphous property of the molecule, it is preferable that the ratio of the cycloalkyl group in the molecule is not too large, and cyclohexyl is preferable from the viewpoint of the stability of the molecule. Among the substituents of X, the expanded conjugated system is advantageous for hole transport, and therefore X is preferably a conjugated group such as an aryl group.

In the present compound, in the explanation of Y, the alkyl chain means an aliphatic hydrocarbon chain, which may be unsubstituted or
It may be substituted with an aryl group, an amino group, a hydroxyl group or an alkoxy group. Since the alkyl chain is not directly involved in hole transport, it is better not to be so large, and C1 to C3 is preferable. The alkylene chain represents an unsaturated aliphatic hydrocarbon chain, which may be unsubstituted or substituted with an alkyl group, an aryl group, an amino group, a hydroxyl group, an alkoxy group, or the like, but is conjugated. Is desirable. The cycloalkyl chain means a cyclic hydrocarbon chain, which may be unsubstituted or substituted with an alkyl group, an aryl group, an amino group, a hydroxyl group or an alkoxy group. The aryl chain refers to an aromatic hydrocarbon chain such as a phenyl chain, a biphenyl chain, a naphthyl chain, a terphenyl chain,
This may also be unsubstituted or substituted with an alkyl group, an aryl group, an amino group, a hydroxyl group, an alkoxy group or the like. The aralkyl chain refers to an aromatic hydrocarbon chain via an aliphatic hydrocarbon chain. Both the aliphatic hydrocarbon and the aromatic hydrocarbon are unsubstituted or substituted with an alkyl group, an amino group, a hydroxyl group or an alkoxy group. It does not matter if it is done. Among the substituents of Y, Y has a role of connecting a carbazole ring and an amino group, and therefore Y is preferably a conjugated chain such as an alkylene chain or an aryl chain, and more preferably an aryl chain.

From the above, specifically, the following general formula (II)
Are preferred.

[Chemical 6] (Here, n represents a natural number, Ar is an aryl group, Ar '
Represents an aryl chain. R ^{1 to} R ⁸ may be the same or different, and may be a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a cycloalkyl group, a fluoroalkyl group, an amino group, a halogen, a nitro group, a cyano group,
It represents at least one kind of substituent selected from a hydroxyl group and an alkoxy group. ) Here, as the aryl group, a phenyl group, a naphthyl group,
Examples thereof include a biphenyl group, a phenanthryl group, a terphenyl group, a pyrenyl group, and the like, and a phenyl group in which a substituent is easily introduced can be simply used. Examples of the aryl chain include a phenyl chain, a biphenyl chain, a naphthyl chain, a terphenyl chain and the like. However, it is preferable that the distance between the carbazole ring and the amino group is not too long, and the phenyl chain is most preferable.

From the above, specifically, the following general formula (II
Most preferred are the compounds of I).

Embedded image (Here, n represents a natural number, R ^{1 to} R ²² may be the same or different, and may be a hydrogen atom, an alkyl group,
It represents at least one kind of substituent selected from an aralkyl group, an aryl group, a cycloalkyl group, a fluoroalkyl group, an amino group, a halogen, a nitro group, a cyano group, a hydroxyl group and an alkoxy group. ) Here, in the description of R ^{1 to} R ²² , the alkyl group refers to an aliphatic hydrocarbon group, which may be unsubstituted or substituted with an aryl group, an amino group, a hydroxyl group, an alkoxy group or the like. Absent. Aliphatic hydrocarbons for amino groups,
Aromatic hydrocarbons, including those substituted with alicyclic hydrocarbons, etc., further, aliphatic hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons are each unsubstituted, alkyl group, aryl group, amino group, It may be substituted with a hydroxyl group or an alkoxy group. The aryl group means an aromatic hydrocarbon group, which may be unsubstituted or substituted with an alkyl group, an amino group, a hydroxyl group or an alkoxy group. Further, the aralkyl group refers to an aromatic hydrocarbon group via an aliphatic hydrocarbon, and the aliphatic hydrocarbon and the aromatic hydrocarbon group may be an alkyl group, an amino group, a hydroxyl group or an alkoxy group, etc. It may be replaced. The cycloalkyl group means a saturated alicyclic hydrocarbon group, which may be unsubstituted or substituted with an alkyl group, an aryl group, an amino group, a hydroxyl group or an alkoxy group. The fluoroalkyl group represents an aliphatic hydrocarbon group partially and / or entirely substituted with fluorine. The alkoxy group refers to an aliphatic hydrocarbon group via an ether bond, and even if the aliphatic hydrocarbon group is unsubstituted,
It may be substituted with an aryl group, an amino group, a hydroxyl group or an alkoxy group. Among the substituents of R, a methyl group or an ethyl group is preferable in order to prevent structural traps due to the overlapping of carbazolyl rings, break the symmetry to improve the amorphous property, and prevent crystallization from occurring. Since the stability of the carbocation of the transport material contributes to hole transport, electron donating groups such as methoxy group and dimethylamino group are also preferable.

The typical structural formulas of the hole transport material in the present invention are shown below, but the present invention is not limited thereto.

[0022]

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The hole transport material in the present invention is carbazo-
It can be synthesized by oxidative polymerization using iron chloride or the like by introducing an amino group from a phenol or carbazol derivative by applying the Ullman reaction. By adjusting the conditions of oxidative polymerization, compounds having various molecular weights can be obtained. In addition, by introducing an amino group into the carbazole or the carbazole derivative after the oxidative polymerization, by-products during the oxidative polymerization can be suppressed.

When this compound is used as a hole transport material, it can be used alone, but when it is used in combination with a derivative, crystallization is less likely to occur. In addition, N, N'-diphenyl-N, N'-di (3
-Methylphenyl) -4,4'-diamine and other triphenylamines, N-isopropylcarbazol and other tertiary amines, pyrazoline derivatives, stilbene compounds, hydrazone compounds, oxadiazole derivatives and phthalocyanine derivatives Heterocyclic compounds represented by C60
The same effect can be obtained when used together with.

The light-emitting material in the present invention is not particularly limited, but in addition to anthracene and pyrene, which have been known as light-emitting materials for a long time, and 8-hydroxyquinoline aluminum described above, for example, Bisstyrylanthracene derivative, tetraphenylbutadiene derivative, coumarin derivative, oxadiazole derivative,
Distyrylbenzene derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, oxadiazole derivatives, thiadiazolopyridine derivatives, and polymer systems include polyphenylenevinylene derivatives, polyparaphenylene derivatives, and polythiophene derivatives. As the dopant added to the light emitting material, the above-mentioned rubrene, quinacridone derivative, phenoxazone 660, DCM1, perinone, perylene, coumarin 540 and the like can be used as they are.

As the electron transporting material in the present invention,
It is necessary to efficiently transport the electrons from the negative electrode between the electrodes to which an electric field is applied, the electron injection efficiency is high, and it is desirable to efficiently transport the injected electrons. For this purpose, it is required that the material has a high electron affinity, a high electron mobility, a high stability, and a small amount of impurities serving as traps during production and use. Examples of the substance satisfying such a condition include oxadiazole derivative and 8-hydroxyquinoline aluminum, but are not particularly limited.

The materials used for the hole transporting layer, the light emitting layer and the electron transporting layer described above can be used to form each layer independently, but as the polymer binder, polyvinyl chloride, polycarbonate, polystyrene, Poly (N-vinylcarbazo-
), Polymethyl methacrylate, polybutyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, hydrocarbon resin, ketone resin, phenoxy resin, polysulfone, polyamide,
Solvent-soluble resins such as ethyl cellulose, vinyl acetate, ABS resin, polyurethane resin, phenol resin, xylene resin, petroleum resin, urea resin, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin,
It is also possible to use the resin dispersed in a curable resin such as a silicone resin.

The method of forming the substance that controls the light emission in the present invention is not particularly limited to resistance heating vapor deposition, electron beam vapor deposition, sputtering method, molecular lamination method, coating method, etc. Beam evaporation is preferable in terms of characteristics. The layer thickness cannot be limited because it depends on the resistance value of the substance that controls light emission, but empirically it is 10 to 10.
It is selected from the range of 00 nm.

The electric energy in the present invention mainly refers to a direct current, but it is also possible to use a pulse current or an alternating current. The current value and voltage value are not particularly limited,
Considering the power consumption and life of the device, the maximum brightness should be obtained with the lowest possible energy.

The light emitting device of the present invention preferably constitutes a display for displaying by a matrix and / or segment system.

The matrix in the present invention is a matrix in which pixels for display are arranged, and a character or an image is displayed by a set of pixels. The shape and size of the pixel depend on the application. For example, square pixels with a side of 300 μm or less are usually used for displaying images and characters on personal computers, monitors, and televisions, and in the case of large displays such as display panels, use pixels with a side of mm order. become. In the case of monochrome display, pixels of the same color may be arranged, but in the case of color display, red, green, and blue pixels are displayed side by side. In this case, there are typically a delta type and a stripe type. Since the light emitting device of the present invention can emit red, green and blue light, multi-color or full-color display can be performed by using the above-mentioned display method. The driving method of this matrix may be either a line-sequential driving method or an active matrix. Line-sequential drive has the advantage that the structure is simple,
In consideration of operating characteristics, the active matrix may be superior in some cases, and it is necessary to use the active matrix properly according to the application.

In the segment type according to the present invention, a pattern is formed so as to display predetermined information, and a predetermined area is made to emit light. Examples include time and temperature display on digital clocks and thermometers, operation status display of audio equipment and electromagnetic cookers, and panel display of automobiles. The matrix display and the segment display may coexist in the same panel.

The light emitting device of the present invention is preferably a backlight. The backlight in the present invention is mainly used for the purpose of improving the visibility of a display device that does not emit light, and is used for a liquid crystal display device, a timepiece, an audio device, an automobile panel, a display board, a sign, and the like. In particular, as a backlight for a liquid crystal display device, in particular, a personal computer for which thinning has been a problem, it is difficult to reduce the thickness because the conventional type is composed of a fluorescent lamp and a light guide plate. The backlights in are characterized by being thin and lightweight.

[0034]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 A glass substrate (15 Ω / □) on which an ITO transparent conductive film was deposited to a thickness of 150 nm was cut into a predetermined size and after etching,
Washing was performed. This was installed in a vacuum vapor deposition apparatus and evacuated until the degree of vacuum in the apparatus became 5 × 10 −4 Pa or less. First, the following compound was vapor-deposited to a thickness of 150 nm, and 8-hydroxyquinoline aluminum was vapor-deposited to a thickness of 100 nm. Next, magnesium is 50 nm and aluminum is 15 nm.
An element having a size of 5 × 5 mm was prepared by vapor deposition of 0 nm. The light emission starting voltage of this light emitting element is 4.5 V, and the maximum brightness is 180
It was 00 cd / m2. The glass transition temperature of HTL1 was 140 ° C., and continuous light emission was possible for 1000 hours or longer.

[0036]

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Example 2 A device prepared in exactly the same manner as in Example 1 except that the following compounds were used, had a light emission starting voltage of 4.8 V and a maximum brightness of 2.
It was 4000 cd / m 2. The glass transition temperature of HTL2 was 152 ° C., and continuous light emission was possible for 1000 hours or longer.

[0038]

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Comparative Example 1 A device obtained in exactly the same manner as in Example 1 except that the triphenyldiamine compound (TPD) was used had a light emission starting voltage of 5.2 V and a maximum luminance of 12000 cd / m 2. The glass transition temperature of TPD was 69 ° C., and the non-light emitting portion increased in several hundred hours, and a remarkable decrease in brightness was observed.

[0040]

INDUSTRIAL APPLICABILITY The present invention can provide a high-brightness light emitting device with high utilization efficiency of electric energy and improved durability.

Claims (10)

[Claims] 1. A device which emits light by electric energy when a substance controlling light emission exists between a positive electrode and a negative electrode, wherein the device contains a compound represented by the following general formula (I). Light emitting element. Embedded image (Here, n represents a natural number, X ¹ and X ² may be the same or different, and may be a hydrogen atom, an alkyl group,
It represents at least one kind of substituent selected from an aralkyl group, an aryl group and a cycloalkyl group. Y represents a single bond, an alkyl chain, an alkylene chain, a cycloalkyl chain, an aryl chain or an aralkyl chain. R ^{1 to} R ⁸ may be the same or different and each is a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a cycloalkyl group, a fluoroalkyl group, an amino group, a halogen, a nitro group, a cyano group, a hydroxyl group. And at least one kind of substituent selected from alkoxy groups. ) 2. The light emitting device according to claim 1, wherein the compound is represented by the following general formula (II). Embedded image (Here, n represents a natural number, Ar is an aryl group, Ar '
Represents an aryl chain. R ^{1 to} R ⁸ may be the same or different, and may be a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a cycloalkyl group, a fluoroalkyl group, an amino group, a halogen, a nitro group, a cyano group,
It represents at least one kind of substituent selected from a hydroxyl group and an alkoxy group. ) 3. The light emitting device according to claim 1, wherein the compound is an N, N-diphenylaminophenylcarbazole derivative represented by the following general formula (III). Embedded image (Here, n represents a natural number, R ^{1 to} R ²² may be the same or different, and may be a hydrogen atom, an alkyl group,
It represents at least one kind of substituent selected from an aralkyl group, an aryl group, a cycloalkyl group, a fluoroalkyl group, an amino group, a halogen, a nitro group, a cyano group, a hydroxyl group and an alkoxy group. ) 4. The light emitting device according to claim 1, wherein the compound is a hole transport material. 5. A light emitting device having at least a positive electrode, a hole transport material,
The light emitting device according to claim 1, which is composed of a light emitting material and a negative electrode. 6. The positive electrode, the hole transporting material, the light emitting material and the negative electrode of the light emitting element have a laminated structure.
The light-emitting element according to any one of the preceding claims. 7. A light emitting device having at least a positive electrode, a hole transport material,
The light emitting device according to claim 1, which is composed of a light emitting material, an electron transporting material, and a negative electrode. 8. The light emitting device according to claim 7, wherein the positive electrode, the hole transporting material, the light emitting material, the electron transporting material and the negative electrode of the light emitting device have a laminated structure. 9. The light emitting device according to claim 1, wherein the light emitting device constitutes a display for displaying by a matrix and / or segment system. 10. The light emitting device according to claim 1, wherein the light emitting device is a backlight.