JP2001196181A - Luminous device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminous device which is excellent in brightness, color purity and a high luminous emission efficiency. SOLUTION: The device in which a luminescence substance exists between a positive electrode and a negative electrode and emits light by electrical energy, is a luminous device containing an organic phosphor which has an imidaso heterocyclic frame expressed with formula (1). R1-R2 may be same or may differ from each other respectively and they are chosen here from hydrogen, an alkyl group, a cycloalxyl group, an aralkyl group, an alkenyl group, a cycloalkenyl group, a alkynyl group, a hydroxyl group, a mercapto group, an alkoxyl group, an alkylthio group, an arylether group, an arylthioether group, an aryl group, a heterocyclic group, halogen, a haloalkane, a haloalkene, a haloalkyne, a cyan group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group, and a siloxanyl group. Ar1 expresses the heterocylce.

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, studies have been actively conducted on organic laminated thin-film light emitting devices in which electrons injected from a cathode and holes injected from an anode emit light when they recombine in an organic phosphor sandwiched between both electrodes. ing. This device has attracted attention because it is thin, emits light with high luminance under a low driving voltage, and emits multicolor light by selecting a fluorescent material.

[0003] This study was carried out by Kodak Corporation. W. Tan
g. et al. showed that the organic laminated thin film element emits light with high luminance (Appl. Phys. Lett. 51 (12)
21, p. 913, 1987), and many research institutions are conducting studies. A typical configuration of an organic laminated thin film light emitting device presented by a research group of Kodak Company is a diamine compound having a hole transporting property and a light emitting layer on an ITO glass substrate.
Aluminum hydroxyquinoline and M as cathode
g: Ag was sequentially provided, and green light emission of 1000 cd / m ² was possible at a driving voltage of about 10 V. The present organic laminated thin-film light-emitting device has a different configuration, such as a device provided with an electron transport layer in addition to the above-described device components, but basically follows the configuration of Kodak Company.

[0004] The light emitting layer is composed of only a host material,
A host material is doped with a guest material.
The light emitting material is required to have three primary colors, but the research on the green light emitting material has been most advanced so far. At present, intensive studies have been made on red light emitting materials and blue light emitting materials with the aim of improving the characteristics. In particular, a blue light-emitting material that can emit light with high luminance and good color purity is desired.

As the host material, the above-mentioned tris (8-
Metal complexes of quinolinol derivatives including quinolinolato) aluminum, benzoxazole derivatives, stilbene derivatives, benzothiazole derivatives, thiadiazole derivatives, thiophene derivatives, tetraphenylbutadiene derivatives, cyclopentadiene derivatives, oxadiazole derivatives, oxadiazole derivative metal complexes And benzazole derivative metal complexes.

As an example of a blue light-emitting host material having relatively good performance, a metal complex obtained by combining a quinolinol derivative with a different ligand (Japanese Patent Laid-Open No. 5-21)
No. 4332) and bisstyrylbenzene derivatives (JP-A-4-117485), but the color purity is not particularly sufficient.

On the other hand, as a dopant material as a guest material, coumarin derivatives such as 7-dimethylamino-4-methylcoumarin, perylene, pyrene and anthracene, which are known to be useful as laser dyes, are known. Fused aromatic ring derivatives, stilbene derivatives, oligophenylene derivatives, furan derivatives, quinolone derivatives, oxazole derivatives, oxadiazole derivatives and the like are known.

[0008]

However, many light-emitting materials (host materials and dopant materials) used in the prior art have low light-emitting efficiency and high power consumption, and have low durability and short element life. Was. In addition, red, green, and blue light emission of three primary colors is required as a full-color display. However, in red and blue light emission, few light emission wavelengths are satisfied, and few light emission peaks have a wide emission peak width and good color purity. In particular, for blue light emission, a material having excellent durability and sufficient luminance and color purity characteristics is required.

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 luminance and excellent color purity.

[0010]

SUMMARY OF THE INVENTION The present invention provides an element which emits light by electric energy in which a light emitting substance is present between a positive electrode and a negative electrode, wherein the element is an imidazo complex represented by the following general formula (1). A light-emitting element comprising an organic phosphor having a ring skeleton.

[0011]

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(Wherein R _{1 and} R ₂ may be the same or different and each represents a 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 , Alkylthio, arylether, arylthioether, aryl, heterocyclic, halogen, haloalkane, haloalkene, haloalkyne, cyano, aldehyde, carbonyl, carboxyl, ester, carbamoyl, amino, nitro , A silyl group,
It is selected from siloxanyl groups. Ar ₁ represents a heterocyclic ring. )

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a positive electrode is made of a conductive metal oxide such as tin oxide, indium oxide, indium tin oxide (ITO) or a metal such as gold, silver or chromium if it is transparent to extract light. Although not particularly limited, such as metals, inorganic conductive substances such as copper iodide and copper sulfide, and conductive polymers such as polythiophene, polypyrrole, and polyaniline, 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, 3
Although an ITO substrate having a resistance of 00 Ω / □ or less functions as an element electrode, a substrate having a resistance of about 10 Ω / □ can be supplied at present. The thickness of the ITO can be arbitrarily selected according to the resistance value, but is usually used in a range of usually 100 to 300 nm. Further, the glass substrate is made of soda lime glass, non-alkali glass, or the like, and the thickness only needs to be sufficient to maintain the mechanical strength.
mm or more is sufficient. For the glass material,
Alkali-free glass is preferred because less ions elute from the glass is preferred, but soda-lime glass 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 method, a sputtering method, and a chemical reaction method.

In the present invention, the cathode is not particularly limited as long as it can efficiently inject electrons into the organic material layer. Generally, platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium , Sodium, potassium, calcium, magnesium, etc., and lithium, sodium, potassium, calcium, magnesium or an alloy containing these low work function metals is effective in improving the device characteristics by increasing the electron injection efficiency. . However, these low work function metals are generally unstable in the air in many cases. For example, a very small amount of lithium or magnesium is added to an organic layer (1 or less in a vacuum deposition film thickness meter).
The following method can be cited as a preferable example in which an electrode having a high stability is used by doping (e.g., nm or less). However, the use of an inorganic salt such as lithium fluoride is also possible. Absent. Furthermore, for electrode protection, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, and inorganic substances such as silica, titania and silicon nitride, polyvinyl alcohol, vinyl chloride, It is preferable to laminate a hydrocarbon polymer or the like. The method for producing these electrodes is not particularly limited, as long as electrical conduction such as resistance heating, electron beam, sputtering, ion plating, and coating can be achieved.

In the present invention, the structure of the luminescent material is 1) a hole transport layer / a light emitting layer, 2) a hole transport layer / a light emitting layer / an electron transport layer, 3) a light emitting layer / an electron transport layer, and 4) May be in any form in which a combination of the above substances is mixed. That is, as the element configuration, in addition to the multilayer laminated structure of the above 1) to 3), a single layer of a luminescent material alone or a layer containing a luminescent material and a hole transporting material or an electron transporting material may be provided as in 4). Further, the luminescent substance in the present invention corresponds to both a substance which emits light by itself and a substance which assists the light emission, and refers to a compound, a layer, or the like involved in light emission.

In the present invention, the hole transporting layer is formed of a hole transporting substance alone or a mixture of two or more kinds of substances or a mixture of a hole transporting substance and a polymer binder.
As a hole transporting substance, it is necessary to efficiently transport holes from the positive electrode between electrodes to which an electric field is applied, and it is desirable to have a high hole injection efficiency and to efficiently transport injected holes. . For that purpose, it is required that the ionization potential be small, the hole mobility be large, the stability be further improved, and impurities serving as traps be hardly generated during production and use. The substance satisfying such conditions is not particularly limited,
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, bis (N-allylcarbazole) or bis (N-alkylcarbazole), pyrazoline derivatives, stilbene compounds, hydrazone compounds, oxadiazole derivatives And a phthalocyanine derivative, a heterocyclic compound represented by a porphyrin derivative, in a polymer system, a polycarbonate or a styrene derivative having the monomer in a side chain, polyvinyl carbazole, polysilane and the like are preferable, but a thin film necessary for element production is formed. The compound is not particularly limited as long as it is a compound capable of injecting holes from the positive electrode and further transporting holes.

In the present invention, the luminescent material may be a host material alone or a combination of a host material and a dopant material.
Any of them may be used. In addition, the dopant material may be included in the entire host material, partially, or may be included. The dopant material may be stacked, dispersed, or the like.

In the present invention, the luminescent material includes an organic phosphor having an imidazo heterocyclic skeleton represented by the following general formula (1).

[0019]

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Here, R _{1 and} R ₂ may be the same or different, and may be hydrogen, an alkyl group, a cycloalkyl group,
Aralkyl group, 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, It is selected from aldehyde group, carbonyl group, carboxyl group, ester group, carbamoyl group, amino group, nitro group, silyl group and siloxanyl group. Ar ₁ represents a heterocyclic ring. Of these substituents, an alkyl group is, for example, a methyl group,
It represents a saturated aliphatic hydrocarbon group such as an ethyl group, a propyl group and a butyl group, which may be unsubstituted or substituted. The cycloalkyl group is, for example, a saturated alicyclic hydrocarbon group such as cyclopropyl, cyclohexyl, norbornyl, and adamantyl, which may be unsubstituted or substituted. The aralkyl group refers to an aromatic hydrocarbon group via an aliphatic hydrocarbon such as a benzyl group and a phenylethyl group, and the aliphatic hydrocarbon and the aromatic hydrocarbon may be unsubstituted or substituted. I don't care. The alkenyl group is, for example, a vinyl group,
It represents an unsaturated aliphatic hydrocarbon group containing a double bond such as an allyl group or a butadienyl group, which may be unsubstituted or substituted. 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, and the aliphatic hydrocarbon group may be unsubstituted or substituted. The alkylthio group is obtained by substituting the oxygen atom of the ether bond of the alkoxy group with a sulfur atom. Further, 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 arylthioether group is a group in which an oxygen atom of an ether bond of the arylether group is substituted with a sulfur atom. 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, which may be unsubstituted or substituted. Further, the heterocyclic group refers to a cyclic structural group having an atom other than carbon, such as a furyl group, a thienyl group, an oxazolyl group, a pyridyl group, a quinolyl group, and a carbazolyl group, which may be unsubstituted or substituted. Absent. Halogen refers to fluorine, chlorine, bromine and iodine. Haloalkanes, haloalkenes, and haloalkynes are those in which some or all of the aforementioned alkyl, alkenyl, and alkynyl groups, such as trifluoromethyl, have been substituted with the aforementioned halogens, and the rest are 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 heterocyclic ring may be unsubstituted or substituted. The silyl group means 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. Further, a ring structure may be formed between adjacent substituents. The ring structure formed may be unsubstituted or substituted.

In the imidazo heterocyclic skeleton of the general formula (1) in the present invention, those having a heterocyclic moiety having an electron-accepting nitrogen atom-containing heterocyclic ring are preferably used. Specific examples include an imidazo heterocyclic skeleton represented by the following general formula (2).

[0022]

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Here, X _{1 to} X ₄ are each selected from a nitrogen atom or a carbon atom, and at least one of them represents a nitrogen atom. R _{3 to} R ₈ may be the same or different, and each represents 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, or an aryl ether. Group, arylthioether group,
It is selected from an aryl group, a heterocyclic group, a halogen, a haloalkane, a haloalkene, a haloalkyne, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group, and a siloxanyl group. However, among R _{5 to} R ₈ , the corresponding X ₁
When X ₄ is a nitrogen atom, it is unsubstituted. These substituents are the same as those described above.

Among the imidazo heterocyclic skeletons of the general formula (2) in the present invention, those which are multimers are effective for holding an amorphous thin film because the molecular weight increases and the glass transition temperature increases. Used for Specific examples include an imidazo heterocyclic skeleton represented by the following general formula (3) or the following general formula (4).

[0025]

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Here, X _{5 to} X ₈ are each selected from a nitrogen atom or a carbon atom, and at least one of them represents a nitrogen atom. R _{9 to} R ₁₃ may be the same or different, and each may be 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, or an aryl ether. Group, arylthioether group,
It is selected from an aryl group, a heterocyclic group, a halogen, a haloalkane, a haloalkene, a haloalkyne, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group, and a siloxanyl group. However, among R _{10 to} R ₁₃ , the corresponding X
₅ If ~X ₈ is a nitrogen atom is unsubstituted. m represents a natural number of 2 or more, and Y ₁ is a single bond or a linking unit for linking a plurality of imidazo heterocyclic skeletons. These substituents are the same as those described above.

[0027]

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Here, X _{9 to} X ₁₂ are each selected from a nitrogen atom or a carbon atom, and at least one of them represents a nitrogen atom. R _{14 to} R ₁₈ may be the same or different, and each represents 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, or an aryl ether. Group, arylthioether group,
It is selected from an aryl group, a heterocyclic group, a halogen, a haloalkane, a haloalkene, a haloalkyne, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group, and a siloxanyl group. However, among R _{15 to} R ₁₈ , the corresponding X
₉ If ~X ₁₂ is a nitrogen atom is unsubstituted. n represents a natural number of 2 or more, and Y ₂ represents a single bond or a linking unit for linking a plurality of imidazo heterocyclic skeletons. These substituents are the same as those described above.

Specific examples of the above imidazo heterocyclic skeleton include the following structures.

[0030]

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[0031]

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The organic phosphor having an imidazo heterocyclic skeleton may be used as a dopant material, but is preferably used as a host material because of its excellent electron transporting ability.

The host material of the light-emitting material is not limited to one kind of organic phosphor having an imidazo heterocyclic skeleton, but may be a mixture of a plurality of organic phosphors having an imidazo heterocyclic skeleton or a known host material. More than one kind may be used as a mixture with an organic phosphor having an imidazo heterocyclic skeleton. Known host materials are not particularly limited, but anthracene, which has long been known as a luminous body,
Fused ring derivatives such as phenanthrene, pyrene, perylene and chrysene; metal complexes of quinolinol derivatives including tris (8-quinolinolato) aluminum; benzoxazole derivatives; stilbene derivatives; benzothiazole derivatives; thiadiazole derivatives; thiophene derivatives;
Tetraphenylbutadiene derivative, cyclopentadiene derivative, oxadiazole derivative, bisstyryl derivative such as bisstyrylanthracene derivative and distyrylbenzene derivative, metal complex combining quinolinol derivative and different ligand, oxadiazole derivative metal complex, benzazole Derivative metal complex, coumarin derivative,
In the case of pyrrolopyridine derivatives, perinone derivatives, thiadiazolopyridine derivatives, and polymer systems, polyphenylenevinylene derivatives, polyparaphenylene derivatives, and polythiophene derivatives can be used.

The dopant material to be added to the light emitting material is not particularly limited, but specific examples include phenanthrene, anthracene, pyrene, tetracene, pentacene, perylene, naphthopyrene, dibenzopyrene, and rubrene. Condensed ring derivatives such as benzoxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, benztriazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, imidazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazoline derivatives, stilbene derivatives, thiophene derivatives , Tetraphenylbutadiene derivatives, cyclopentadiene derivatives, bisstyryl anthracene derivatives, bisstyryl derivatives such as distyrylbenzene derivatives, diaza Ndasen derivatives, furan derivatives,
Benzofuran derivatives, phenylisobenzofuran, dimesitylisobenzofuran, di (2-methylphenyl) isobenzofuran, di (2-trifluoromethylphenyl) isobenzofuran, isobenzofuran derivatives such as phenylisobenzofuran, dibenzofuran derivatives, 7
-Dialkylaminocoumarin derivative, 7-piperidinocoumarin derivative, 7-hydroxycoumarin derivative, 7-methoxycoumarin derivative, 7-acetoxycoumarin derivative, 3-benzthiazolyl coumarin derivative, 3-benzimidazolyl coumarin derivative, 3- Coumarin derivatives such as benzoxazolyl coumarin derivatives, dicyanomethylenepyran derivatives, dicyanomethylenethiopyran derivatives,
Polymethine derivatives, cyanine derivatives, oxobenzanthracene derivatives, xanthene derivatives, rhodamine derivatives, fluorescein derivatives, pyrylium derivatives, carbostyril derivatives, acridine derivatives, bis (styryl)
Benzene derivatives, oxazine derivatives, phenylene oxide derivatives, quinacridone derivatives, quinazoline derivatives,
Pyrrolopyridine derivatives, furopyridine derivatives, 1,2,2
A 5-thiadiazolopyrene derivative, a perinone derivative, a pyrrolopyrrole derivative, a squarylium derivative, a biolanthrone derivative, a phenazine derivative, an acridone derivative, a diazaflavin derivative, and the like can be used as they are, but an isobenzofuran derivative is particularly preferably used.

In the present invention, the electron transporting material needs to efficiently transport electrons from the negative electrode between the electrodes to which an electric field is applied, and has a high electron injection efficiency and a high efficiency of transporting the injected electrons. Is desirable. 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. As a substance satisfying such conditions, quinolinol derivative metal complex represented by 8-hydroxyquinoline aluminum, tropolone metal complex, flavonol metal complex, perylene derivative, perinone derivative, naphthalene, coumarin derivative, oxadiazole derivative, aldazine derivative,
There are bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives and the like, but there is no particular limitation. These electron transporting materials may be used alone or may be laminated or mixed with different electron transporting materials.

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. As the polymer binder, polyvinyl chloride, polycarbonate, polystyrene, poly (N- Vinyl carbazole), 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, phenolic 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.

In the present invention, the method for forming the luminescent material is not particularly limited, such as resistance heating evaporation, electron beam evaporation, sputtering, molecular lamination, and coating method. It is preferable in terms of characteristics. The thickness of the layer depends on the resistance of the luminescent material and cannot be limited, but is selected from the range of 1 to 1000 nm.

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,
In consideration of the power consumption and the life of the device, the maximum luminance should be obtained with the lowest possible energy.

In the present invention, a matrix 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, a square pixel having a side of 300 μm or less is generally used for displaying images and characters on a personal computer, a monitor, and a television. . For monochrome display, pixels of the same color may be arranged, but for color display, red, red,
Green and blue pixels are displayed side by side. In this case, there are typically a delta type and a stripe type. The matrix may be driven by either a line-sequential driving method or an active matrix. The line-sequential driving has the advantage that the structure is simpler. However, in consideration of the operation characteristics, the active matrix is sometimes superior, and therefore it is necessary to use the same depending on the application.

In the present invention, the segment type refers to a pattern formed so as to display predetermined information,
Light is emitted from the determined area. 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.

In the present invention, a backlight is mainly used for improving the visibility of a display device which 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 a backlight for a liquid crystal display device, especially a personal computer application in which thinning is an issue, considering that it is difficult to reduce the thickness because the conventional type is made of a fluorescent lamp or a light guide plate, the present invention The backlight is thin and lightweight.

[0042]

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 (available from Asahi Glass Co., Ltd., 15 Ω / □, electron beam deposited) on which an ITO transparent conductive film was deposited to a thickness of 150 nm was cut into a size of 30 × 40 mm and etched. The obtained substrate was subjected to ultrasonic cleaning with acetone and "Semicocrine 56" (manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes, 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. Immediately before this element is fabricated,
V-ozone treatment was performed, the apparatus was set in a vacuum evaporation apparatus, and the apparatus was evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁵ Pa or less. By the resistance heating method, 4,4'-
Bis (N- (m-tolyl) -N-phenylamino) biphenyl was deposited to a thickness of 100 nm. Next, as a luminescent material,
1,3-bis (2- (1-benzyl-imidazo [4,5
-B] pyridyl)) benzene was laminated to a thickness of 50 nm. Next, 2,9-dimethyl-4,
7-diphenyl-1,10-phenanthroline is added to 100
It was laminated to a thickness of nm. Next, after doping the organic layer with lithium to a thickness of 0.5 nm, aluminum was vapor-deposited to a thickness of 200 nm to form a cathode, thereby producing a 5 × 5 mm square device. The film thickness referred to here is a value indicated by a crystal oscillation type film thickness monitor. Good light emission was obtained from this light emitting device.

Example 2 Except that 1,3,5-tris (2- (1-benzyl-imidazo [4,5-b] pyridyl)) benzene was used as the luminescent material, the luminescence was performed in exactly the same manner as in Example 1. An element was manufactured. Good light emission was obtained from this light emitting device.

Example 3 The steps up to the deposition of each organic layer were performed in the same manner as in Example 1. First, as a hole transport material, 4,
4′-bis (N- (m-tolyl) -N-phenylamino) biphenyl was deposited to a thickness of 150 nm and 1,3-bis (2
-(1-Benzyl-imidazo [4,5-b] pyridyl)) benzene was deposited to a thickness of 50 nm. Next, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline was laminated with a thickness of 100 nm as an electron transporting material. Next, after doping the organic layer with lithium to a thickness of 0.5 nm, aluminum was deposited to a thickness of 200 nm to form a 5 × 5 m
An m-square element was manufactured. The film thickness here is a value indicated by a crystal oscillation type film thickness monitor. When the light emitting device was driven at 1 mA pulse (duty ratio 1/60, pulse current value 60 mA) in a vacuum cell, light emission was confirmed.

Example 4 A glass substrate (15 Ω / □, manufactured by Asahi Glass Co., Ltd., electron beam deposited) on which an ITO transparent conductive film was deposited to a thickness of 150 nm was cut into 30 × 40 mm, and a 300 μm pitch (remaining width 270 μm) was obtained by photolithography. ) X 32 stripes were patterned. One side of the ITO stripe in the long side direction is 1.2 in order to facilitate electrical connection with the outside.
It is expanded to a pitch of 7 mm (opening width 800 μm).
The obtained substrate was subjected to ultrasonic cleaning with acetone and "Semicocline 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 the device was manufactured, and was placed in a vacuum evaporation apparatus, and the degree of vacuum in the apparatus was 5 ×.
Evacuation was performed until the pressure became 10 ⁻⁴ Pa or less. First, 4,4′-bis (N- (m
-Tolyl) -N-phenylamino) biphenyl to 150
1,3-bis (2- (1-benzyl-imidazo [4,5-b] pyridyl)) benzene was deposited to a thickness of 50 nm. Next, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline was laminated with a thickness of 100 nm as an electron transporting material. The film thickness referred to here is a value indicated by a crystal oscillation type film thickness monitor. Next, thickness 50μ
A mask having 16 openings of 250 μm (remaining width of 50 μm, corresponding to a pitch of 300 μm) provided on a Kovar plate having a thickness of 250 m by wet etching is exchanged in a vacuum so as to be orthogonal to the ITO stripe. It was fixed with a magnet from the back so as to be in close contact. Then, after doping the organic layer with 0.5 nm of lithium, aluminum was vapor-deposited at 200 nm to fabricate a 32 × 16 dot matrix element. When this element was driven in matrix,
Characters could be displayed without crosstalk.

[0047]

According to the present invention, it is possible to provide a light emitting device having high luminous efficiency and excellent color purity. It is particularly effective for blue light emission.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K007 AB02 AB03 AB04 BA06 CA01 CB01 DA00 DB03 EB00 FA01 5C094 AA08 AA10 AA60 BA27 CA12 CA19 EA05 EB02 FB01 HA03 HA05 HA06 HA08

Claims (7)

[Claims] 1. An element which emits light by electric energy in which a light emitting substance is present between a positive electrode and a negative electrode, wherein the element has an imidazo heterocyclic skeleton represented by the following general formula (1): A light-emitting element comprising: Embedded image (Wherein R _{1 and} R ₂ may be the same or different and each represents a 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 , Aryl ether group, aryl thioether group,
It is selected from an aryl group, a heterocyclic group, a halogen, a haloalkane, a haloalkene, a haloalkyne, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group, and a siloxanyl group. Ar ₁ represents a heterocyclic ring. ) 2. The light emitting device according to claim 1, wherein the imidazo heterocyclic skeleton is represented by the following general formula (2). Embedded image (Where X _{1 to} X ₄ are each selected from a nitrogen atom or a carbon atom, and at least one is a nitrogen atom. R ₃
To R ₈ may be the same or different, and hydrogen,
Alkyl group, cycloalkyl group, aralkyl group, alkenyl group, cycloalkenyl group, alkynyl group, hydroxyl group,
Mercapto group, alkoxy group, alkylthio group, arylether group, arylthioether group, aryl group,
Heterocyclic group, halogen, haloalkane, haloalkene, haloalkyne, cyano group, aldehyde group, carbonyl group,
It is selected from a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group, and a siloxanyl group. However, when corresponding X _{1 to} X ₄ among R _{5 to} R ₈ are nitrogen atoms, they are unsubstituted. ) 3. The light emitting device according to claim 1, wherein the imidazo heterocyclic skeleton is represented by the following general formula (3). Embedded image (Where X _{5 to} X ₈ are each selected from a nitrogen atom or a carbon atom, and at least one is a nitrogen atom. R ₉
To R ₁₃ may be the same or different, and hydrogen,
Alkyl group, cycloalkyl group, aralkyl group, alkenyl group, cycloalkenyl group, alkynyl group, hydroxyl group,
Mercapto group, alkoxy group, alkylthio group, arylether group, arylthioether group, aryl group,
Heterocyclic group, halogen, haloalkane, haloalkene, haloalkyne, cyano group, aldehyde group, carbonyl group,
It is selected from a carboxyl group, an ester group, a carbamoyl group, an amino group, a nitro group, a silyl group, and a siloxanyl group. However, when the corresponding X _{5 to} X ₈ among R _{10 to} R ₁₃ is a nitrogen atom, it is unsubstituted. m represents a natural number of 2 or more, and Y1 is a single bond or a linking unit for linking a plurality of imidazo heterocyclic skeletons. ) 4. The light emitting device according to claim 1, wherein the imidazo heterocyclic skeleton is represented by the following general formula (4). Embedded image (Where X _{9 to} X ₁₂ are each selected from a nitrogen atom or a carbon atom, and at least one is a nitrogen atom. R
_{14 to} R ₁₈ may be the same or different, and each represents a 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, or an aryl ether group. An arylthioether group, an aryl group, a heterocyclic group, a halogen, a haloalkane, a haloalkene, a haloalkyne, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a carbamoyl group,
It is selected from an amino group, a nitro group, a silyl group, and a siloxanyl group. However, among R _{15 to} R ₁₈ , the corresponding X _{9 to} X
_{When 12} is a nitrogen atom, it is unsubstituted. n represents a natural number of 2 or more, and Y ₂ represents a single bond or a linking unit for linking a plurality of imidazo heterocyclic skeletons. ) 5. The light emitting device according to claim 1, wherein said organic phosphor is a light emitting material. 6. The light emitting device according to claim 1, wherein said organic phosphor is an electron transporting material. 7. The light emitting device according to claim 1, wherein the light emitting device is a display for displaying in a matrix and / or a segment system.