JPH1126163A - Light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting device making high bright emission possible even at low voltage and with high durability by including a compound having a imino stilbene skeleton. SOLUTION: A compound contained in a light emitting device is represented by the formula. In the formula, R1 -R11 may be the same or different and represent at least one kind of substituted group selected from the group comprising a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a cycroalkyl group, a fluoroalkyl group, an amino group, a halogen atom, a nitro group, a cyano group, a hydroxyl group, an alkoxy group, and an aryl ether group. As the aryl group used in R9 , a non-substituted aromatic hydrocarbon group or an aromatic hydrocarbon group substituted with an alkyl group, an amino group, a hydroxyl group, or an alkoxy group is listed. The compound has an imino stilbene skeleton and is suitable especially as a hole carrying material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, active research has been conducted on organic thin-film light emitting devices that emit light when electrons injected from a negative electrode and holes injected from a positive electrode recombine in an organic phosphor sandwiched between both electrodes. I have. This element 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 configuration of the organic multilayer thin film light emitting device presented by Kodak Company is a diamine compound having a hole transporting property and a light emitting layer on an ITO glass substrate.
-Hydroxyquinoline aluminum, and Mg: Ag as a negative electrode were sequentially provided, and green light emission of 1000 candela / m 2 was possible at a driving voltage of about 10 V. The present organic laminated thin-film light-emitting element, in addition to the above-mentioned element components, may have a modified configuration such as an electron transport layer, but basically follows the configuration of Kodak Company .

[0004] With respect to the carrier transporting material in the organic laminated thin film element, a high carrier transporting capability is required for improving the luminous efficiency with respect to power. Selection of the material is effective. Furthermore, it has been shown that it is important not to form an exciplex at the interface with the light emitting layer in order to efficiently convert electric energy into light. The film thickness and film forming ability are also important requirements in actual device fabrication. The carrier transporting material includes an electron transporting material and a hole transporting material.

[0005] Specific examples of electron transporting materials include oxadiazole derivatives and aluminum 8-hydroxyquinoline.

On the other hand, hole transport materials include hydrazone-based compounds (JP-A-57-101844 and JP-A-58-15936) and stilbene-based compounds (JP-A-57-148750; 1958-19704
No. 3), a triphenylamine-based compound (JP-B-58)
JP-A-32372, JP-A-5-198377,
JP-A-4-308688), oxadiazole derivatives (JP-B-34-10966) and phthalocyanine derivatives (JP-A-57-51781) are known.

[0007]

As described above, conventionally, an organic laminated thin-film light-emitting element has a high carrier transport ability, a good film-forming property, and a thermal stability and an electrochemical stability during light emission. A material having both properties has been desired. However, conventional materials have insufficient carrier transporting ability, have low heat resistance, and have many problems such as interface disorder due to crystallization.

An object of the present invention is to solve such a problem and to provide a highly durable element which can emit light with high luminance even at a low voltage.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an element in which a substance which emits light exists between a positive electrode and a negative electrode and which emits light by electric energy, wherein the element has the following general formula (I):
This is achieved by a light emitting device comprising a compound having an iminostilbene skeleton represented by

[0010]

Embedded image (Where R1 to R11 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, a hydroxyl group, Represents an at least one substituent selected from a group, an alkoxy group, and an aryl ether group, wherein the aryl group used for R9 is unsubstituted or substituted with an alkyl group, an amino group, a hydroxyl group, or an alkoxy group. An object of the present invention is an element in which a substance which emits light exists between a positive electrode and a negative electrode and which emits light by electric energy, wherein the element has the following general formula (II) This is achieved by a light-emitting device comprising a compound having an iminostilbene skeleton represented by the formula (1).

[0011]

Embedded image (Where n represents a natural number, and R1 to R11 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, a hydroxyl group, an alkoxy group, and an aryl ether group.) The object of the present invention is to provide a light-emitting substance between a positive electrode and a negative electrode, This is achieved by a light-emitting element which emits light by energy, the light-emitting element including a compound having an iminostilbene skeleton represented by the following general formula (IV).

[0012]

Embedded image (Where X represents a single bond, an alkyl chain, an alkylene chain, a cycloalkyl chain, an aryl chain, an aralkyl chain, an alkyl ether chain, or an aryl ether chain.
R40 may be the same or different, and each 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, a hydroxyl group, an alkoxy group and At least one selected from aryl ether groups
Represents a type of substituent. )

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A positive electrode according to the present invention is made of a conductive metal oxide such as tin oxide, indium oxide, indium tin oxide (ITO), or gold, silver, chromium, if it is transparent to extract light. Metals such as, for example, inorganic conductive substances such as copper iodide and copper sulfide, and conductive polymers such as polythiophene, polypyrrole, and polyaniline are not particularly limited, but 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 having a resistance of 300Ω / □ or less functions as an element electrode, but a substrate having a resistance of about 20Ω / □ or less should be used because a substrate of about 10Ω / □ can be supplied at present. Is particularly desirable. The thickness of the ITO can be arbitrarily selected according to the resistance value.
It is often used between ３００300 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 material of the glass, alkali-free glass is preferable because it is better that ions eluted from the glass are small,
Soda lime glass provided with a barrier coat such as SiO ₂ is also commercially available and can be used. The method of forming the ITO film is not particularly limited, such as an electron beam evaporation 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 injecting electrons efficiently or a substance (for example, an electron transport layer) adjacent to the substance which controls light emission. Generally, platinum, gold, silver, copper, iron, tin, aluminum, indium, lithium, sodium, potassium,
Examples include calcium and magnesium. In order to improve the device characteristics by increasing the electron injection efficiency, 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 air, and platinum, gold, silver,
It is preferable to stack a metal such as copper, iron, tin, aluminum and indium, or an alloy using these metals, and an inorganic substance such as silica and titania, and a polymer such as polyvinyl alcohol and vinyl chloride. The method for producing these electrodes is not particularly limited, as long as electrical conduction can be achieved, such as resistance heating evaporation, electron beam evaporation, sputtering, ion plating, and coating.

The structure of the substance that controls light emission in the present invention is as follows:
1) a hole transporting material / a light emitting material, 2) a hole transporting material / a light emitting material / an electron transporting material, 3) a light emitting material / an electron transporting material, and 4) a form in which a combination of the above substances is mixed.
Any of these may be used. That is, in addition to the above-described multilayered structures 1) to 3), a single layer of a luminescent material alone or a layer containing a luminescent material and a hole transporting material and / or an electron transporting material may be provided as in 4).

The substance controlling light emission in the present invention contains a compound having an iminostilbene skeleton represented by the following general formula (I). The compound having the iminostilbene skeleton is particularly preferably used as a hole transporting material.

[0017]

Embedded image (Where R1 to R11 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, a hydroxyl group, Represents an at least one substituent selected from a group, an alkoxy group, and an aryl ether group, wherein the aryl group used for R9 is unsubstituted or substituted with an alkyl group, an amino group, a hydroxyl group, or an alkoxy group. In the compound represented by the general formula (I) used in the present invention, in the description of R1 to R13, the alkyl group is, for example, a methyl group, an ethyl group, a propyl group, a butyl group. Represents a saturated aliphatic hydrocarbon group such as an amino group, a hydroxyl group, or an amino group. It may be substituted by a lucoxy group or the like. Although the alkyl group improves the amorphous property of the molecule, it does not directly participate in the hole transport. Therefore, the proportion of the alkyl group in the molecule is preferably not so large, and is preferably about C1 to C4. The aryl group refers to, for example, an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group, a terphenyl group, and a pyrenyl group.
It may be substituted with an amino group, a hydroxyl group or an alkoxy group. Among the 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. The aralkyl group refers to an aromatic hydrocarbon group via an aliphatic hydrocarbon such as a benzyl group and a phenylethyl group.
Both the aliphatic hydrocarbon and the aromatic hydrocarbon may be unsubstituted or substituted with an alkyl group, amino group, hydroxyl group, alkoxy group, or the like. Since the aliphatic hydrocarbon portion of the aralkyl group does not directly participate in hole transport, it is preferably not so large, and is preferably about C1 to C2. Among the aralkyl groups, aromatic hydrocarbon groups are preferably those having strong conjugation, and thus phenyl groups, naphthyl groups, phenanthryl groups, pyrenyl groups and the like are preferable. Further, a cycloalkyl group refers to, for example, a saturated alicyclic hydrocarbon group such as cyclopropyl, cyclopentyl, or 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. The cycloalkyl group improves the amorphous property of the molecule, but does not directly participate in hole transport. Therefore, it is preferable that the proportion of the cycloalkyl group in the molecule is not so large, and cyclohexyl is preferable in view of the stability of the molecule. The fluoroalkyl group is part of fluorine and / or
Or an aliphatic hydrocarbon group in which all are substituted. Amino groups include those substituted with aliphatic hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons, and the like.Furthermore, aliphatic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons are each unsubstituted, It may be substituted with an alkyl group, an aryl group, an amino group, a hydroxyl group or an alkoxy group. An alkoxy group refers to an aliphatic hydrocarbon group via an ether bond, and the aliphatic hydrocarbon group may be unsubstituted or substituted with an aryl group, an amino group, a hydroxyl group, an alkoxy group, or the like. The aryl ether group represents an aromatic hydrocarbon group via an ether bond,
The aromatic hydrocarbon group may be unsubstituted or substituted with an alkyl group, an amino group, a hydroxyl group or an alkoxy group.

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 small, it will volatilize. Therefore, it is desirable to increase the molecular weight without impairing the ratio of the iminostilbene skeleton in the compound. Therefore, the following general formula (I
Compounds represented by I) are preferred.

[0019]

Embedded image (Where n represents a natural number, and R1 to R11 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 Represents at least one substituent selected from a group, a cyano group, a hydroxyl group, an alkoxy group and an aryl ether group.) In the compound represented by the general formula (II) used in the present invention, When used in various vapor deposition methods, etc., if the molecular weight is too large, it may be decomposed without sublimation. Therefore, it is desired that the molecular weight does not exceed about 1000, and n is preferably within 5 and preferably within 3 Is more preferable. However, this is not the case when the film is formed by a coating method or the like. The description of R1 to R11 is the same as that of the compound represented by the general formula (I), but among the substituents of R, a conjugated system such as an aryl group is preferred because an expanded conjugated system is advantageous for hole transport. Is desirable,
The N atom plays a central role in hole transport, and preferably replaces R7 in the sense of extending its conjugation. Examples of the aryl group include a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group, a terphenyl group, and a pyrenyl group. A phenyl group into which a substituent can be easily introduced can be used easily.

From the above, specifically, the following general formula (II)
Compounds represented by I) are more preferred.

Embedded image (Where R1 to R30 may be the same or different, and each 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, a hydroxyl group, Represents at least one substituent selected from a group, an alkoxy group and an aryl ether group.) In the compound represented by the above general formula (III) used in the present invention, R1 to R30 are described in the above general formula (I In the same manner as in the case of the compound represented by the formula (1), among the substituents of R, a methyl group or an ethyl group is preferable in order to break the symmetry to increase the amorphous property and to make crystallization difficult to occur. Since the stability of the cation radical of the hole transport material contributes to hole transport, electron donating groups such as methoxy group and dimethylamino group are also preferable. Good.

As a method for increasing the molecular weight without impairing the ratio of the iminostilbene skeleton in the compound, the iminostilbene skeleton can be linked at the 9-position.

From the above, specifically, the following general formula (IV)
Compounds represented by are also preferred.

[0023]

Embedded image (Where X represents a single bond, an alkyl chain, an alkylene chain, a cycloalkyl chain, an aryl chain, an aralkyl chain, an alkyl ether chain, or an aryl ether chain.
R40 may be the same or different, and each 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, a hydroxyl group, an alkoxy group and At least one selected from aryl ether groups
Represents a type of substituent. In the compound represented by the above general formula (IV) used in the present invention, the description of R1 to R40 is the same as that of the compound represented by the above general formula (I). Represents an aliphatic hydrocarbon chain, and the aliphatic hydrocarbon chain may be unsubstituted or substituted with an aryl group, an amino group, a hydroxyl group, an alkoxy group, or the like. Since the alkyl chain does not directly participate in hole transport, it is preferable that the alkyl chain is not so large, and is preferably about C1 to C3. The alkylene chain refers to an unsaturated aliphatic hydrocarbon chain, and the unsaturated aliphatic hydrocarbon chain may be unsubstituted or substituted with an alkyl group, an aryl group, an amino group, a hydroxyl group, an alkoxy group, or the like. However, it is desirable that they be conjugate. The cycloalkyl chain refers to a cyclic hydrocarbon chain, and the cyclic hydrocarbon chain may be unsubstituted or substituted with an alkyl group, an aryl group, an amino group, a hydroxyl group, an alkoxy group, or the like. The aryl chain refers to an aromatic hydrocarbon chain such as a phenyl chain, a biphenyl chain, a naphthyl chain, and a terphenyl chain,
The aromatic hydrocarbon chain may be unsubstituted or substituted with an alkyl group, an aryl group, an amino group, a hydroxyl group or an alkoxy group. An aralkyl chain refers to an aromatic hydrocarbon chain via an aliphatic hydrocarbon chain.Either an aliphatic hydrocarbon or an aromatic hydrocarbon is unsubstituted, but is substituted with an alkyl group, an amino group, a hydroxyl group or an alkoxy group. It may be done. The alkyl ether chain refers to an aliphatic hydrocarbon chain via an ether bond,
The aliphatic hydrocarbon chain may be unsubstituted or substituted with an aryl group, amino group, hydroxyl group, alkoxy group, or the like. An aryl ether chain refers to an aromatic hydrocarbon chain via an ether bond, and the aromatic hydrocarbon chain may be unsubstituted or substituted with an alkyl group, amino group, hydroxyl group, alkoxy group, or the like. Among the substituents of Y, since they have a role of linking iminostilbene rings, Y is preferably a conjugated chain such as an alkylene chain or an aryl chain, and more preferably an aryl chain. Examples of the aryl chain include a phenyl chain, a biphenyl chain, a naphthyl chain, and a terphenyl chain. The distance between the iminostilbene rings is preferably not too small, and the biphenyl chain is most preferable.

From the above, specifically, compounds represented by the following general formula (V) are more preferred.

Embedded image (Where R1 to R48 may be the same or different, and each may be hydrogen, alkyl, aralkyl, aryl, cycloalkyl, fluoroalkyl, amino, halogen, nitro, cyano, hydroxyl, Represents at least one kind of substituent selected from a group, an alkoxy group and an aryl ether group.) In the compound represented by the above general formula (V) used in the present invention, R1 to R48 are described in the above general formula (I In the same manner as in the case of the compound represented by R), among the substituents of R, a methyl group or an ethyl group is preferable in order to increase the amorphous property by breaking the symmetry and to make crystallization difficult. Since the stability of the carbocation of the hole transport material contributes to the hole transport, an electron donating group such as a methoxy group or a dimethylamino group is also preferable. .

The typical structural formula of the hole transporting material according to the present invention is shown below, but the present invention is not limited thereto.

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The hole transporting material in the present invention is prepared from iminostilbene or an iminostilbene derivative by Ullman.
It can be synthesized by oxidative polymerization using iron chloride or the like by introducing various substituents by application of the reaction. By adjusting the conditions of the oxidative polymerization, compounds having various molecular weights can be obtained. Further, by modifying iminostilbene or an iminostilbene derivative after oxidative polymerization, by-products during oxidative polymerization can be suppressed. Also, iminostilbene or an iminostilbene derivative can be linked using the Ullman reaction.

When this compound is used as a hole transport material, it can be used alone, but when used in combination with a derivative, crystallization hardly occurs. Also, other hole transporting materials such as N, N′-diphenyl-N, triphenylamines such as N′-di (3-methylphenyl) -4, 4′-diamine, and N-isopropylcarbazo- The same effect can be obtained when used together with a tertiary amine such as phenyl, a pyrazoline derivative, a stilbene compound, a hydrazone compound, a heterocyclic compound represented by an oxadiazole derivative or a phthalocyanine derivative, or C60.

The light-emitting material in the present invention is not particularly limited. In addition to anthracene and pyrene, which have been known as light emitters, 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 to be 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 electrons from the negative electrode between the electrodes to which an electric field is applied, and it is desirable that the electron injection efficiency is high and the injected electrons are transported efficiently. 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. Materials satisfying such conditions include oxadiazole derivatives and 8-hydroxyquinoline aluminum, but are not particularly limited.

The above materials used for the hole transporting layer, the light emitting layer and the electron transporting layer can be used alone to form each layer. Examples of the polymer binder include polyvinyl chloride, polycarbonate, polystyrene, and the like. Poly (N-vinyl carbazo-
), 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 which controls light emission in the present invention is not particularly limited, such as resistance heating evaporation, electron beam evaporation, sputtering, molecular lamination, and coating. Beam evaporation is preferred in terms of properties. The thickness of the layer cannot be limited because it depends on the resistance value of the substance that controls light emission.
00 nm.

Although the electric energy in the present invention mainly refers to a direct current, a pulse current or an alternating current can also be used. The current value and voltage value are not particularly limited,
In consideration of the power consumption and life of the device, it is necessary to obtain the maximum brightness with the lowest possible energy.

It is preferable that the light emitting device of the present invention constitutes a display for displaying by a matrix and / or segment system.

The matrix according to the present invention refers to a matrix in which pixels for display are arranged in a lattice, and displays a character or an image 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 normally used for displaying images and characters on personal computers, monitors, and televisions. For large displays such as display panels, pixels with a side on the order of mm are used. 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 element of the present invention can emit red, green, and blue light, multi-color or full-color display can be performed by using the display method. The matrix may be driven by either a line-sequential driving method or an active matrix. Line-sequential drive has the advantage of a simpler structure,
In consideration of the operation characteristics, the active matrix is sometimes superior, so it is necessary to use the active matrix properly depending on 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 emits light. For example, there are a time display and a temperature display on a digital clock or a thermometer, an operation state display of an audio device, an electromagnetic cooker, or the like, and a panel display of an automobile. The matrix display and the segment display may coexist in the same panel.

The light emitting device of the present invention is also preferably used as a backlight. The backlight in the present invention,
It is mainly used for improving the visibility of a display device that does not emit light, and is used for a liquid crystal display device, a clock, an audio device, an automobile panel, a display panel, a sign, and the like. In particular, as for the backlight for liquid crystal display devices, particularly for personal computer applications where thinning is an issue, the present invention is considered to be difficult because the conventional type is made of a fluorescent lamp or a light guide plate, and it is difficult to make it thin. Is characterized by its thinness and light weight.

[0037]

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 / □, electron beam evaporated product, manufactured by Asahi Glass Co., Ltd.) on which an ITO transparent conductive film was deposited to a thickness of 150 nm
The wafer was cut into a size of 40 mm and etched. The obtained substrate was subjected to ultrasonic cleaning with acetone and semicocrine 56 for 15 minutes each, and then with ultrapure water. Subsequently, the substrate was subjected to ultrasonic cleaning with isopropyl alcohol for 15 minutes, immersed in hot methanol for 15 minutes, and dried. The substrate was subjected to UV-ozone treatment for one hour immediately before the device was manufactured, placed in a vacuum evaporation apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 −4 Pa or less. First, the following compound (HTL1) was deposited to a thickness of 150 nm by a resistance heating method, and 8-hydroxyquinoline aluminum was deposited to a thickness of 100 nm. Next, 50 nm of magnesium and 150 nm of aluminum
Vapor deposition was performed to produce a 5 × 5 mm square device. The film thickness referred to here is a value displayed on a crystal oscillation type film thickness monitor corrected by a value measured by a surface roughness meter. The light emission starting voltage of this light emitting element was 4.9 V, and the maximum luminance was 25000 candela / square meter. The glass transition temperature of HTL1 is 110 ° C., and the device is driven by a 1 mA pulse in a vacuum cell (Dut).
When the y ratio was 1/60 and the current value during the pulse was 60 mA, continuous light emission was possible for 1000 hours or more while maintaining 70% of the initial luminance.

[0039]

Embedded image

Example 2 A device produced in the same manner as in Example 1 except that the following compounds were used, the light emission starting voltage was 5.1 V, and the maximum luminance was 1
It was 8000 candela / square meter. The glass transition temperature of HTL2 was 98 ° C., and continuous light emission was possible for 1000 hours or more while maintaining the luminance of 70% of the initial luminance.

[0041]

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Example 3 A glass substrate (available from Asahi Glass Co., Ltd., 15 Ω / □, electron beam vapor-deposited product) on which an ITO transparent conductive film was deposited to a thickness of 150 nm was used.
Cut to × 40mm, 30 by photolithography
The pattern was processed into a 0 μm pitch (remaining width 270 μm) × 32 stripes. One side of the long side of the ITO stripe is 1.27 m to facilitate electrical connection with the outside.
The pitch is expanded to m pitches (opening width 800 μm). The obtained substrate was subjected to ultrasonic cleaning with acetone and semicocrine 56 for 15 minutes each, and then with ultrapure water. Subsequently, the substrate was subjected to ultrasonic cleaning with isopropyl alcohol for 15 minutes, immersed in hot methanol for 15 minutes, and dried. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the element, and was placed in a vacuum evaporation apparatus, and the degree of vacuum in the apparatus was 5 × 10 −4 P
The gas was exhausted until the pressure became less than a. First, the following compound (HTL1) was deposited to a thickness of 150 nm by a resistance heating method, and 8-hydroxyquinoline aluminum was deposited to a thickness of 100 nm. The film thickness referred to here is a value displayed on a crystal oscillation type film thickness monitor corrected by a value measured by a surface roughness meter. Next, thickness 50
A mask having 16 openings of 250 μm (remaining width of 50 μm, corresponding to a pitch of 300 μm) provided by wet etching in a μm Kovar plate was replaced by a mask in vacuum so as to be orthogonal to the ITO stripe. It was fixed with a magnet from the back side so as to adhere. Then, 50 nm of magnesium and 150 nm of aluminum were deposited to produce a 32 × 16 dot matrix element. When this device was driven in a matrix, characters could be displayed clearly without crosstalk.

Comparative Example 1 A device obtained in the same manner as in Example 1 except that the triphenyldiamine compound (TPD) was used, the light emission starting voltage was 5.2 V, and the maximum luminance was 12,000 candela / square meter. . The glass transition temperature of TPD was 69 ° C., and the non-light emitting portion became large and the luminance was reduced by half in 200 hours. The luminance retention after 1000 hours was 40% or less.

[0044]

According to the present invention, it is possible to provide a high-brightness light-emitting device which has high utilization efficiency of electric energy, can emit light even at a low voltage, and has improved durability.

Claims (12)

[Claims] An element which emits light by electric energy, wherein a substance which emits light exists between a positive electrode and a negative electrode, wherein the element contains a compound having an iminostilbene skeleton represented by the following general formula (I). A light-emitting element, comprising: Embedded image (Where R1 to R11 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, a hydroxyl group, Represents at least one substituent selected from a group, an alkoxy group, and an aryl ether group, wherein the aryl group used for R9 is unsubstituted or substituted with an alkyl group, an amino group, a hydroxyl group, or an alkoxy group. It is an aromatic hydrocarbon group.) 2. An element which emits light by electric energy in which a substance responsible for light emission exists between a positive electrode and a negative electrode, wherein the element contains a compound having an iminostilbene skeleton represented by the following general formula (II). A light-emitting element, comprising: Embedded image (Where n represents a natural number, and R1 to R11 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 Represents at least one substituent selected from a group, a cyano group, a hydroxyl group, an alkoxy group and an aryl ether group.) 3. The light emitting device according to claim 2, wherein the compound having an iminostilbene skeleton is represented by the following general formula (III). Embedded image (Where R1 to R30 may be the same or different, and each 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, a hydroxyl group, Represents at least one substituent selected from a group, an alkoxy group and an aryl ether group.) 4. An element in which a substance responsible for light emission exists between a positive electrode and a negative electrode and emits light by electric energy, wherein the element contains a compound having an iminostilbene skeleton represented by the following general formula (IV). A light-emitting element, comprising: Embedded image (Where X represents a single bond, an alkyl chain, an alkylene chain, a cycloalkyl chain, an aryl chain, an aralkyl chain, an alkyl ether chain, or an aryl ether chain.
R40 may be the same or different, and each 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, a hydroxyl group, an alkoxy group and At least one selected from aryl ether groups
Represents a type of substituent. ) 5. The light emitting device according to claim 4, wherein the compound having an iminostilbene skeleton is represented by the following general formula (V). Embedded image (Where R1 to R48 may be the same or different, and each may be hydrogen, alkyl, aralkyl, aryl, cycloalkyl, fluoroalkyl, amino, halogen, nitro, cyano, hydroxyl, Represents at least one substituent selected from a group, an alkoxy group and an aryl ether group.) 6. The light emitting device according to claim 1, wherein the compound is a hole transport material. 7. A light-emitting device comprising at least a positive electrode, a hole transport material,
6. The light emitting device according to claim 1, comprising a light emitting material and a negative electrode. 8. The light emitting device according to claim 7, wherein the positive electrode, the hole transport material, the light emitting material and the negative electrode have a laminated structure.
The light-emitting element according to any one of the preceding claims. 9. A light emitting device comprising at least a positive electrode, a hole transport material,
The light emitting device according to claim 1, comprising a light emitting material, an electron transport material, and a negative electrode. 10. The light emitting device according to claim 9, 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. 11. The light emitting device according to claim 1, wherein the light emitting device constitutes a display for displaying in a matrix and / or segment system. 12. The light emitting device according to claim 1, wherein the light emitting device is a backlight.