JP2003133075A - Luminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminescent element having high luminous efficiency, high luminance and excellent color purity. SOLUTION: In this luminescent element, a luminescent substance exists between an anode and a cathode, and light is generated by electric energy. The luminescent substance contains a compound having a carbazole skeltal structure represented by the general formula (1) and a triplet luminescent material. (Each of R<1> -R<8> is selected from hydrogen, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group, a cycloalkenyl group, an alkinyl group, a hydroxyl group, a melcapto group and the like. However, at least one of R<1> -R<4> is a linking group Y, and Y is selected either independently from a single bond, an alkyl chain, an alkylene chain, a cycloalkyl chain, an aryl chain, an amino chain, a heterocyclic chain, a silyl chain, an ether chain or a thioether chain or from the combinations of them. R<9> is selected from hydrogen, an alkyl group and aryl group. n is 2 or a higher natural number.).

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 element that can be used in the field of.

[0002]

2. Description of the Related Art In recent years, active research has been carried out on organic laminated thin-film light emitting devices in which electrons injected from a cathode and holes injected from an anode emit light when recombined in an organic phosphor sandwiched between both electrodes. ing. This element has attracted attention because it is thin, has high-luminance light emission under a low driving voltage, and has multicolor light emission by selecting a fluorescent material.

This work was carried out by Kodak Corp. W. Tan
Since g. et al. showed that the organic laminated thin film light emitting device emits light with high brightness (Appl. Phys. Lett. 51 (1
2) 21, p. 913, 1987), many research institutes are investigating. A typical structure of an organic laminated thin film light emitting device presented by a Kodak research group is a diamine compound having a hole-transporting property on a tin indium oxide (ITO) glass substrate and tris (8-quinolinolato) which is a light emitting layer.
Aluminum and Mg: Ag are sequentially provided as a cathode, and the drive voltage of about 10 V is 1000 cd /
A green light emission of m ² was possible. Some of the current organic laminated thin-film light-emitting elements have different configurations such as an element having an electron transport layer in addition to the above-mentioned element components, but basically follow the configuration of Kodak Corporation.

As the light emitting material constituting the above light emitting layer,
A host material alone or a host material doped with a dopant material is used. It is required that the light emitting material has three primary colors of red, green and blue for full color display.

Conventionally, a fluorescent (singlet emission) material has been generally used as a light emitting material. However, due to a difference in spin multiplicity when electrons and holes are recombined to excite molecules. , Singlet excitons 25%, triplet excitons 75%
It has been attempted to use phosphorescent (triplet emission) materials in order to improve the emission efficiency, and the group at Princeton University emits light more than conventional fluorescent materials. It shows that the efficiency is significantly higher (Appl. Phys. Lett. 75, 4
(1999)).

[0006]

However, the light emitting device manufactured by the above-mentioned conventional technique is not sufficiently durable, and the phosphorescent material itself is improved, and the hole transport material, host material, electron transport material, etc. Improvement is desired, and improvement of the host material that has the greatest effect on light emission is desired.

[0007] Therefore, an object of the present invention is to solve the problems of the prior art and to provide a light emitting device having high luminous efficiency, high color purity and excellent durability.

[0008]

That is, the present invention is an element in which a light emitting substance exists between an anode and a cathode and emits light by electric energy, and the light emitting substance is a carbazole skeleton represented by the general formula (1). A light-emitting device comprising a compound having a and a triplet light-emitting material.

[0009]

[Chemical 3]

(R ^{1 to} R ⁸ are each hydrogen, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group,
Cycloalkenyl group, alkynyl group, hydroxyl group, mercapto group, alkoxy group, alkylthio group, aryl ether group, arylthioether group, aryl group, heterocyclic group, halogen, haloalkane, haloalkene, haloalkyne, cyano group, aldehyde group, carbonyl group, It is selected from the group consisting of a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, and a ring structure between adjacent substituents. However, R ¹ ~
At least one of R ⁴ is a linking group Y, Y is a single bond,
It is selected from an alkyl chain, an alkylene chain, a cycloalkyl chain, an aryl chain, an amino chain, a heterocyclic chain, a silyl chain, an ether chain, or a thioether chain, either alone or in combination. R ⁹ is selected from hydrogen, an alkyl group and an aryl group. n is a natural number of 2 or more. )

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the anode is tin oxide, indium oxide, IT if transparent to take out light.
Conductive metal oxides such as O, metals such as gold, silver and chromium, inorganic conductive substances such as copper iodide and copper sulfide, and conductive polymers such as polythiophene, polypyrrole and polyaniline are not particularly limited. It is particularly preferable to use ITO glass or Nesa glass. The resistance of the electrode is not limited as long as it can supply a sufficient current for light emission of the light emitting element, but is preferably low resistance from the viewpoint of power consumption of the light emitting element. For example, if ITO glass of 300Ω / □ or less functions as an element electrode, it is now possible to supply a substrate of about 10Ω / □.
It is particularly preferable to use a low resistance product.

When the ITO glass is used, the thickness of the ITO film can be arbitrarily selected according to the resistance value, but usually it is preferably 100 to 300 nm. Further, the thickness of the glass substrate may be any thickness sufficient to maintain the mechanical strength, and specifically, it is preferably 0.5 mm or more. As for the material of the glass substrate, non-alkali glass is preferable because it is preferable that the amount of ions eluted from the glass is small, but soda lime glass having a barrier coat such as commercially available SiO ₂ can also be used. Alternatively, a plastic substrate may be used.

The ITO film forming method is not particularly limited, such as electron beam method, sputtering method and chemical reaction method.

In the present invention, the cathode is not particularly limited as long as it is made of a substance capable of efficiently injecting electrons into a light emitting substance, and specifically, platinum, gold, silver, copper, iron, tin, zinc, aluminum, Examples thereof include indium, chromium, lithium, cesium, sodium, potassium, calcium and magnesium. In particular, lithium, cesium, sodium, potassium, calcium, magnesium or alloys containing these low work function metals are effective for increasing electron injection efficiency and improving device characteristics.

However, since these low work function metals are generally unstable in the atmosphere in general, for example, trace amounts of lithium, cesium and magnesium (1 nm or less in the film thickness gauge display of vacuum deposition) are present in the organic layer. It is preferable to use a highly stable electrode doped with, but it is also possible to use an inorganic salt such as lithium fluoride, and it is not particularly limited thereto. Furthermore, platinum for electrode protection,
Metals such as gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, and silica,
Preferred examples include laminating inorganic materials such as titania and silicon nitride, polyvinyl alcohol, vinyl chloride, and hydrocarbon polymers.

The method for producing the above-mentioned cathode is not particularly limited as long as conduction can be achieved, such as a resistance heating method, an electron beam method, a sputtering method, an ion plating method and a coating method.

In the present invention, the luminescent substance refers to a compound that is involved in light emission, which corresponds to both a substance which emits light by itself and a substance which assists the light emission. Specifically, it corresponds to a light emitting material, a hole transporting material, an electron transporting material, a hole blocking material and the like.

The light-emitting device of the present invention may have various constitutions other than the anode and the cathode, for example, 1) hole transport layer /
Light-emitting layer, 2) hole-transporting layer / light-emitting layer / electron-transporting layer, 3) light-emitting layer / electron-transporting layer, 4) hole-transporting layer / light-emitting layer / hole-blocking layer, 5) hole-transporting layer / light-emitting layer / Hole blocking layer / electron transporting layer, 6) light emitting layer / hole blocking layer / electron transporting layer, and 7)
Examples include the case of a light emitting layer.

The hole transport layer is a layer for injecting holes from the anode and further transporting holes, and the material used for the hole transport layer (hereinafter referred to as the hole transport material) is used alone or It is formed by laminating and mixing two or more kinds of substances or by using a mixture of a hole transporting material and a polymer binder described later. The hole transporting material is a material that efficiently transports holes from the anode between the electrodes to which an electric field is applied, has a high hole injection efficiency, and efficiently transports the injected holes. Is preferred. For that purpose, it is required to be made of a material which has a low ionization potential, a high hole mobility, a high stability, and an impurity which becomes a trap and is hard to be generated at the time of manufacturing and use. To satisfy such a condition, N,
N'-diphenyl-N, N'-di (3-methylphenyl) -4,4'-diphenyl-1,1'-diamine,
N, N'-dinaphthyl-N, N'-diphenyl-4,
Triphenylamines such as 4′-diphenyl-1,1′-diamine, carbazole derivatives such as bis (N-allylcarbazole) or bis (N-alkylcarbazole) s, pyrazoline derivatives, stilbene compounds, hydrazone compounds, A heterocyclic compound represented by an oxadiazole derivative, a phthalocyanine derivative, a porphyrin derivative, or a polycarbonate having a side chain of the above monomer in the polymer system, a styrene derivative, polyvinylcarbazole, polysilane, or the like is preferably used. The compound is not particularly limited as long as it is a compound capable of forming a necessary thin film, injecting holes from the anode, and further transporting holes.

The light emitting layer is a layer which actually controls light emission by accumulating the electric energy injected from the anode and the cathode as energy for light emission. The material used for the light emitting layer (hereinafter referred to as the light emitting material) is preferably a compound having fluorescence or phosphorescence.

Further, when light emission is obtained by using a light emitting material, energy is accumulated, a case where a single light emitting material is used for actual light emission and energy transition are utilized to separate functions and combine a plurality of light emitting materials. It may be used. In the latter case, it is classified into a light emitting material (hereinafter, referred to as a host material) that is responsible for storing electric energy and a light emitting material (hereinafter, a dopant material) that receives the stored energy and actually controls light emission. Such a method of functional separation is called a doping method, and by this method, high efficiency, high color purity,
A highly durable light emitting element can be obtained.

These light-emitting materials can be used alone or in combination of two or more kinds, and the light-emitting layer can be used in a multi-layer.

In the doping method, the dopant material may be contained in the entire host material, may be partially contained, or may be included in the host material. May be laminated.

In the present invention, the light-emitting substance needs to include a compound having a carbazole skeleton and a triplet light-emitting material, and the triplet light-emitting material itself often plays a role of emitting light, so that it particularly constitutes a light-emitting layer. It is preferably contained in the light emitting material.

In order to obtain light emission efficiently, it is necessary to cause the recombination of electrons and holes in the light emitting layer. However, of the recombination energies, those not used for light emission become heat.
The light emitting layer is most susceptible to damage. A compound having a carbazole skeleton has a hole-transporting property and thus is suitably used as a hole-transporting material, but since it has a large excitation energy, it is also suitably used as a host material for a triplet light-emitting material. Since the compound having a carbazole skeleton has excellent heat resistance, it is preferably used in the light emitting layer. That is, it is preferably contained in the same layer as the triplet light emitting material.

A compound having a carbazole skeleton is characterized in that it is linked by an aromatic ring of carbazole, which facilitates various molecular designs. Examples of the compound having such a carbazole skeleton include organic phosphors represented by the following general formula (1).

[0027]

[Chemical 4]

(R ^{1 to} R ⁸ are each hydrogen, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group,
Cycloalkenyl group, alkynyl group, hydroxyl group, mercapto group, alkoxy group, alkylthio group, aryl ether group, arylthioether group, aryl group, heterocyclic group, halogen, haloalkane, haloalkene, haloalkyne, cyano group, aldehyde group, carbonyl group, It is selected from the group consisting of a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, and a ring structure between adjacent substituents. However, R ¹ ~
At least one of R ⁴ is a linking group Y, Y is a single bond,
It is selected from an alkyl chain, an alkylene chain, a cycloalkyl chain, an aryl chain, an amino chain, a heterocyclic chain, a silyl chain, an ether chain, or a thioether chain, either alone or in combination. R ⁹ is selected from hydrogen, an alkyl group and an aryl group. n is a natural number of 2 or more. )
The gist of the compound having a carbazole skeleton used in the present invention is to have a plurality of carbazole skeletons in the molecule. As the substituent R, hydrogen on the carbazole skeleton and substituents having properties equivalent thereto are listed in view of the effect of the present invention. That is, for example, hydrogen, alkyl group, cycloalkyl group, aralkyl group, alkenyl group, cycloalkenyl group, alkynyl group, hydroxyl group, mercapto group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, aryl group, heterocyclic group. , Halogen, haloalkane, haloalkene, haloalkyne, cyano group, aldehyde group, carbonyl group, carboxyl group, ester group, carbamoyl group,
Examples thereof include an amino group, a nitro group, a silyl group, a siloxanyl group, and a ring structure between adjacent substituents.

The alkyl group refers to a saturated aliphatic hydrocarbon group such as methyl group, ethyl group, propyl group and butyl group, which may be unsubstituted or substituted. The cycloalkyl group refers to a saturated alicyclic hydrocarbon group such as cyclopropyl, cyclohexyl, norbornyl, adamantyl, etc., which may be unsubstituted or substituted. Further, the aralkyl group refers to an aromatic hydrocarbon group via an aliphatic hydrocarbon such as a benzyl group or a phenylethyl group, and both the aliphatic hydrocarbon and the aromatic hydrocarbon may be unsubstituted or substituted. I don't care. The alkenyl group means an unsaturated aliphatic hydrocarbon group containing a double bond such as vinyl group, allyl group and butadienyl group, which may be unsubstituted or substituted. In addition, the cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond such as a cyclopentenyl group, a cyclopentadienyl group, and a cyclohexene group, which may be unsubstituted or substituted. . The alkynyl group means an unsaturated aliphatic hydrocarbon group containing a triple bond, such as an acetylenyl group, which may be unsubstituted or substituted.

The alkoxy group refers to an aliphatic hydrocarbon group via an ether bond such as a methoxy group,
The aliphatic hydrocarbon group may be unsubstituted or substituted. The alkylthio group is an alkoxy group having an ether bond oxygen atom substituted with a sulfur atom.
The aryl ether group refers to an aromatic hydrocarbon group via an ether bond such as a phenoxy group, and the aromatic hydrocarbon group may be unsubstituted or substituted. Further, the aryl thioether group is a group in which an oxygen atom of an ether bond of the aryl ether group is substituted with a sulfur atom. The aryl group is, for example, a phenyl group,
Shows aromatic hydrocarbon groups such as naphthyl group, biphenyl group, phenanthryl group, terphenyl group, pyrenyl group,
This may be unsubstituted or substituted. Also,
The heterocyclic group is, for example, a furyl group, a thienyl group, an oxazolyl group, a pyridyl group, a quinolyl group, a carbazolyl group, or another cyclic structure group having an atom other than carbon, which may be unsubstituted or substituted. Halogen means fluorine, chlorine, bromine and iodine.

The haloalkane, haloalkene and haloalkyne are, for example, a trifluoromethyl group and the like, in which a part or all of the above alkyl group, alkenyl group and alkynyl are substituted with the above halogen, and the remaining portion may be unsubstituted. It may be replaced. Aldehyde groups, carbonyl groups, ester groups, carbamoyl groups, and amino groups include those substituted with aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, heterocycles, and the like. The cyclic hydrocarbon, aromatic hydrocarbon and heterocycle may be unsubstituted or substituted. The silyl group represents a silicon compound group such as a trimethylsilyl group, which may be unsubstituted or substituted. The siloxanyl group refers to a silicon compound group via an ether bond such as a trimethylsiloxanyl group, which may be unsubstituted or substituted. Moreover, you may form a ring structure between adjacent substituents. The ring structure formed may be unsubstituted or substituted.

Among the compounds having a carbazole skeleton, those having a dicarbazolyl skeleton have a rigid molecule and are further excellent in heat resistance. Therefore, in the present invention, the compound having a carbazole skeleton represented by the general formula (2) is particularly preferable. Compounds are preferably used.

[0033]

[Chemical 5]

(R ^{10 to} R ²³ are each hydrogen, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group,
Cycloalkenyl group, alkynyl group, hydroxyl group, mercapto group, alkoxy group, alkylthio group, aryl ether group, arylthioether group, aryl group, heterocyclic group, halogen, haloalkane, haloalkene, haloalkyne, cyano group, aldehyde group, carbonyl group, It is selected from the group consisting of a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, and a ring structure between adjacent substituents. R ²⁴ and R
Each ²⁵ is selected from hydrogen, an alkyl group and an aryl group. ) Specific examples of the compound having a carbazole skeleton include the following structures.

[0035]

[Chemical 6]

[0036]

[Chemical 7]

As the host material of the light emitting material, only one kind of compound having a carbazole skeleton may be used, or a compound having a plurality of carbazole skeletons may be mixed, and further, a compound having a carbazole skeleton and one of known host materials may be used. You may use it, mixing with more than one kind.

The host material is not particularly limited, but includes condensed ring derivatives such as anthracene, phenanthrene, pyrene, perylene, chrysene, which have been known as light emitters, and tris (8-quinolinolato) aluminum. Bisstyryl such as metal complex of quinolinol derivative, benzoxazole derivative, stilbene derivative, benzthiazole derivative, thiadiazole derivative, thiophene derivative, tetraphenylbutadiene derivative, cyclopentadiene derivative, oxadiazole derivative, bisstyrylanthracene derivative and distyrylbenzene derivative Derivative, carbazole derivative such as bis (N-carbazolyl) biphenyl, triazole derivative,
Phenanthroline derivative, triphenylamine derivative,
Metal complex combining quinolinol derivative and different ligand, oxadiazole derivative metal complex, benzazole derivative metal complex, coumarin derivative, pyrrolopyridine derivative, perinone derivative, thiadiazolopyridine derivative,
In the polymer system, polyphenylene vinylene derivatives, polyparaphenylene derivatives, polythiophene derivatives and the like can be used.

Specific examples of the triplet light emitting material include tris (2-phenylpyridyl) iridium complex, tris {2- (2-thiophenyl) pyridyl} iridium complex, and tris {2- (2-benzothiophenyl) pyridyl. } Iridium complex, tris (2-phenylbenzothiazole) iridium complex, tris (2-phenylbenzoxazole) iridium complex, trisbenzoquinolineiridium complex, bis (2-phenylpyridyl) (acetylacetonato) iridium complex, bis {2 -(2-
Thiophenyl) pyridyl} iridium complex, bis {2-
(2-benzothiophenyl) pyridyl} (acetylacetonato) iridium complex, bis (2-phenylbenzothiazole) (acetylacetonato) iridium complex, bis (2-phenylbenzoxazole) (acetylacetonato) iridium complex, bis Benzoquinoline (acetylacetonato) iridium complex, bis {2-
(2,4-Difluorophenyl) pyridyl} (acetylacetonato) iridium complex, tetraethylporphyrin platinum complex, {tris (cenoyltrifluoroacetone) mono (1,10-phenanthroline)} europium complex, {tris (cenoyltrifluoroacetone) ) Mono (4,7-diphenyl-1,10-phenanthroline)} europium complex, {tris (1,3-diphenyl-1,3-propanedione) mono (1,10-phenanthroline)} europium complex, trisacetylacetoneterbium Examples thereof include, but are not limited to, complexes. Among the phosphorescent (triplet emission) materials, an iridium complex or a platinum complex is preferably used because it has good emission characteristics.

As the dopant material of the light emitting material, only one of the above triplet light emitting materials may be used, or a plurality of triplet light emitting materials may be mixed and used. Furthermore, one or more kinds of known singlet dopant materials and triplet light emitting materials may be used. You may mix and use with a light emitting material.

The known singlet dopant material is not particularly limited, but specifically, conventionally known phenanthrene, anthracene, pyrene, tetracene, pentacene, perylene, naphthopyrene, dibenzopyrene, rubrene. Such as fused ring derivatives, benzoxazole derivatives, benzthiazole derivatives, benzimidazole derivatives, benztriazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, imidazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazoline derivatives, thiophene derivatives, tetraphenyl Butadiene derivatives, cyclopentadiene derivatives, bisstyryl anthracene derivatives, bisstyryl derivatives such as distyrylbenzene derivatives, pyrromethene derivatives and Metal complex, furan derivative, benzofuran derivative, phenylisobenzofuran, dimesitylisobenzofuran, di (2-methylphenyl) isobenzofuran, di (2-trifluoromethylphenyl) isobenzofuran, isobenzofuran derivative such as phenylisobenzofuran, Dibenzofuran derivative, 7-dialkylaminocoumarin derivative, 7-piperidinocoumarin derivative, 7-hydroxycoumarin derivative, 7-methoxycoumarin derivative, 7-acetoxycoumarin derivative, 3-benzthiazolylcoumarin derivative, 3-benzimidazolylcoumarin Derivative, coumarin derivative such as 3-benzoxazolyl coumarin derivative, dicyanomethylenepyran derivative, dicyanomethylenethiopyran derivative, polymethine derivative, cyanine derivative, oxoben Anthracene derivatives, xanthene derivatives, rhodamine derivatives, fluorescein derivatives, pyrylium derivatives, carbostyril derivatives, acridine derivatives, oxazine derivatives, polyphenylene oxide derivatives, quinacridone derivatives, quinazoline derivatives, pyrrolopyridine derivatives, furopyridine derivatives,
1,2,5-thiadiazolopylene derivative, perinone derivative, pyrrolopyrrole derivative, squarylium derivative, violanthrone derivative, phenazine derivative, acridone derivative, diazaflavin derivative and the like can be used.

In the present invention, the electron transport layer is a layer which is responsible for injecting electrons from the cathode and further transporting the electrons. The material used for the electron transport layer (hereinafter referred to as electron transport material) needs to efficiently transport the electrons from the cathode between the electrodes to which an electric field is applied. The electron injection efficiency is high, and the injected electrons are efficient. Good transportation is preferable. For that purpose, it is required to be made of a material having a high electron affinity, a high electron mobility, an excellent stability, and an impurity which becomes a trap and which is unlikely to be generated at the time of production and use. As an electron-transporting material satisfying these conditions, a quinolinol derivative metal complex represented by tris (8-quinolinolato) aluminum, a tropolone metal complex, a flavonol metal complex, a perylene derivative,
Examples thereof include perinone derivatives, naphthalene, coumarin derivatives, oxadiazole derivatives, aldazine derivatives, bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, but are not particularly limited. These electron transporting materials may be used alone, or may be used by being laminated or mixed with different electron transporting materials.

In the present invention, the hole blocking layer is a layer which efficiently blocks holes from the anode from flowing to the cathode without recombination. The material used for the hole blocking layer (hereinafter referred to as a hole blocking material) is an efficient material that allows holes from the anode to flow to the cathode side without recombination in consideration of the transport balance of holes and electrons. It is necessary to be able to block, and it is preferable that the hole injection efficiency is low. For that purpose, it is required to be made of a material having a large ionization potential, a small hole mobility, an excellent stability, and an impurity that becomes a trap, which is hard to be generated during manufacturing and use. As the hole blocking material satisfying such a condition, the above electron transporting material can be used, but a material having a low electron transporting ability may be used. These hole blocking materials may be used alone or in a laminated or mixed with different hole blocking materials.

The above hole transport layer, light emitting layer, electron transport layer,
The material used for the hole blocking layer can be used to form each layer independently, and further, as a polymer binder, polyvinyl chloride, polycarbonate, polystyrene, poly (N-vinylcarbazole), polymethylmethacrylate, polybutyl. Methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, hydrocarbon resin, ketone resin, phenoxy resin, polysulfone, polyamide, ethyl cellulose, vinyl acetate, AB
Solvent-soluble resins such as S resin and polyurethane resin, phenol resin, xylene resin, petroleum resin, urea resin,
It is also possible to use it by dispersing it in a curable resin such as a melamine resin, an unsaturated polyester resin, an alkyd resin, an epoxy resin or a silicone resin.

In the present invention, the method for forming each layer constituting the luminescent material is not particularly limited, and the resistance heating method, the electron beam method, the sputtering method, the molecular laminating method, the coating method and the like are not particularly limited. Method and electron beam method are preferable in terms of characteristics. The thickness of each layer cannot be limited because it depends on the resistance value, but is usually 1 to 1000 nm.
Is preferred.

In the present invention, the electric energy 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 light emitting device, the maximum brightness should be obtained with the lowest possible energy.

The light emitting device of the present invention comprises a matrix and / or
Alternatively, the display is preferably a segment type display.

The matrix is a matrix in which pixels for display are arranged in a grid, and characters and images are displayed by a set of pixels. The shape and size of the pixel depend on the application. For example, a quadrangular pixel with a side of 300 μm or less is usually used for displaying images and characters on a personal computer, a monitor, a television, and in the case of a large display such as a display panel, a pixel with a side of mm is used. . 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. The driving method of this matrix may be either a line-sequential driving method or an active matrix. The line-sequential driving has an advantage that the structure is simple, but in consideration of the operation characteristics, the active matrix may be superior in some cases. Therefore, it is necessary to use the active matrix depending on the application.

In the segment system, a pattern is formed so as to display predetermined information, and a predetermined area is made to emit light. For example, a time and temperature display on a digital clock or a thermometer, an operation state display of an audio device or an electromagnetic cooker, a panel display of an automobile, and the like can be given. The matrix display and the segment display may coexist in the same panel.

[0050]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples, the film thickness is the crystal oscillation type film thickness monitor display value.

Example 1 A glass substrate (manufactured by Asahi Glass Co., Ltd., 15 Ω / □, electron beam method product) on which an ITO transparent conductive film was deposited to a thickness of 150 nm was cut into 30 × 40 mm and etched. The obtained substrate is "Semicoclin 56" (manufactured by Furuuchi Chemical Co., Ltd.)
And ultrasonic cleaning with ultrapure water for 15 minutes and dried. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing a light emitting device, placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁵ Pa or less. According to the resistance heating method, first, 4,4'-bis (N
60 nm of-(1-naphthyl) -N-phenylamino) biphenyl (αNPD) was deposited. Next, ethylcarbazole tetramer (EtCz4) linked at the 3 and 6-positions was used as a host material of the light emitting material, and a tris (2-phenylpyridyl) iridium complex (Ir (pp
y) ₃ ) was used to co-evaporate to a thickness of 30 nm so that the dopant was 8 wt%. Next, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BTCPN) was evaporated to a thickness of 10 nm as a hole blocking layer. Next, as an electron transporting material, tris (8-quinolinol) was used.
The aluminum complex was evaporated to a thickness of 50 nm. Next, after doping the organic layer with 0.5 nm of lithium, aluminum was vapor-deposited with 200 nm to serve as a cathode, and a 5 × 5 mm square light emitting device was produced. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light-emitting device, and high-luminance green emission with favorable color purity was obtained.

In addition, the above light emitting device was
Pulse drive (Duty ratio 1/60, pulse current value 6)
0 mA), an emission spectrum similar to the phosphorescence spectrum of the dopant material was observed, and high-brightness green emission with good color purity was confirmed.

Furthermore, when the durability was evaluated by driving with a direct current of 20 mA / square centimeter, high-brightness green light emission with good color purity was obtained even after 100 hours.

Comparative Example 1 A light emitting device was produced in exactly the same manner as in Example 1 except that 4,4′-bis (N-carbazolyl) biphenyl (CBP) was used as the host material of the light emitting material. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light-emitting element, and high-intensity green light emission with favorable color purity was obtained. The durability was evaluated at a DC drive of 20 mA / square centimeter for 100 hours. After that, a remarkable decrease in brightness was observed.

Example 2 3,3'-bis {9- (1
A light emitting device was produced in exactly the same manner as in Example 1 except that -naphthyl) carbazole} was used. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light-emitting device, and high-luminance green emission with favorable color purity was obtained.

Example 3 Bis {2- (2-benzothiophenyl) pyridyl} (acetylacetonate) as a dopant material for a light emitting material
A light emitting device was produced in exactly the same manner as in Example 2 except that the iridium complex was used. An emission spectrum similar to the phosphorescence spectrum of the dopant material was observed from this light-emitting device, and high-luminance red emission with favorable color purity was obtained.

Example 4 A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam method product) on which an ITO transparent conductive film was deposited to a thickness of 150 nm was cut into 30 × 40 mm, and 300 μm pitch (remaining width was obtained by photolithography method. 270 μm) × 32 stripes were patterned. In order to facilitate electrical connection to the outside, one side of the ITO stripe in the long side direction is 1.
It is widened to a pitch of 27 mm (opening width 800 μm). The obtained substrate was ultrasonically cleaned for 15 minutes each with "Semicoclin 56" and ultrapure water, and then dried. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing a light emitting device,
Installed in a vacuum evaporation system, the degree of vacuum in the system is 5 x 10
^It was evacuated to ^-4 Pa or less. By the resistance heating method,
First, 4,4'-bis (N- (1-
Naphthyl) -N-phenylamino) biphenyl (αNP
D) was vapor-deposited at 60 nm. Next, ethylcarbazole tetramer (EtCz4) linked at the 3 and 6-positions was used as a host material of the light emitting material, and tris (2-
Phenylpyridyl) iridium complex (Ir (pp
y) ₃ ) was used to co-evaporate to a thickness of 30 nm so that the dopant was 8 wt%. Next, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BTCPN) was evaporated to a thickness of 10 nm as a hole blocking layer. Next, as an electron transporting material, tris (8-quinolinol) was used.
The aluminum complex was evaporated to a thickness of 50 nm. Next, 16 250 μm openings (remaining widths of 50 μm and 300 μm) were formed on a 50 μm-thick Kovar plate by wet etching.
a mask provided with a (μm pitch) ITO in vacuum
Replace the mask so that it is orthogonal to the stripe,
The TO substrate was fixed with a magnet from the back so that the TO substrate was in close contact. Then, after doping the 0.5 nm organic layer with lithium,
Aluminum was evaporated to a thickness of 200 nm to produce a 32 × 16 dot matrix device. When this device was matrix-driven, characters could be displayed without crosstalk.

[0058]

The light emitting device of the present invention has high luminous efficiency,
It has high brightness and excellent color purity, and is particularly effective for blue light emission.

Claims (6)

[Claims] 1. A device in which a light emitting substance is present between an anode and a cathode, and which emits light by electric energy, wherein the light emitting substance comprises a compound having a carbazole skeleton represented by the general formula (1) and a triplet light emitting material. A light-emitting element comprising: [Chemical 1] (R ^{1 to} R ⁸ are each hydrogen, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a mercapto group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, Aryl group, heterocyclic group, halogen, haloalkane, haloalkene, haloalkyne, cyano group,
It is selected from an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, or a ring structure between adjacent substituents. However, at least one of R ^{1 to} R ⁴ is a linking group Y, and Y is a single bond, an alkyl chain, an alkylene chain, a cycloalkyl chain, an aryl chain, an amino chain,
It is selected from a heterocyclic chain, a silyl chain, an ether chain, or a thioether chain, either alone or in combination. R ⁹ is selected from hydrogen, an alkyl group and an aryl group. n is a natural number of 2 or more. ) 2. R ^{1 to} R ⁸ are each hydrogen, an alkyl group,
It is an alkoxy group, an aryl group, a heterocyclic group, an amino group, or a ring structure between adjacent substituents, and Y is a single bond, an alkylene chain, an aryl chain, an amino chain, or a heterocyclic chain. The light emitting device according to claim 1, which is selected from a combination thereof. 3. The light emitting device according to claim 1, wherein the compound having a carbazole skeleton is represented by the following general formula (2). [Chemical 2] (R ^{10 to} R ²³ are each hydrogen, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a mercapto group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, Aryl group, heterocyclic group, halogen,
From haloalkane, haloalkene, haloalkyne, cyano group, aldehyde group, carbonyl group, carboxyl group, ester group, carbamoyl group, amino group, nitro group, silyl group, siloxanyl group, or ring structure between adjacent substituents To be elected. R ²⁴ and R ²⁵ are each selected from hydrogen, an alkyl group and an aryl group. ) 4. The light emitting device according to claim 1, wherein the compound having a carbazole skeleton and the triplet light emitting material are contained in the same layer. 5. The light emitting device according to claim 1, wherein the triplet light emitting material is an iridium complex or a platinum complex. 6. The light emitting device according to claim 1, which is a display for displaying by a matrix and / or segment system.