JP2001338764A - Luminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a red luminescent element which is superior in electrical energy efficiency and in color purity. SOLUTION: This luminescent element includes a luminescent substance present between a positive electrode and a negative electrode and emits light, having a peak wavelength of 580-720 nm. The luminescent element contains at least a fluorescent compound, having a fluorescent peak wavelength of 540-720 nm and a condensed ring derivative. The condensed ring derivative is expressed by general formula 1, where R1-R16 is hydrogen, alkyl, alkoxy, halogen, aryl, aralkyl, alkenyl, aryl ether, heterocycle, cyano, aldehyde, carbonyl, ester, carbamoyl, amino or an aromatic, aliphatic or heterocyclic condensed ring formed between an adjacent substituted group and itself.

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] Among multicolor light emission, red light emission has been studied as a useful light emission color. Conventionally, perylene-based such as bis (diisopropylphenyl) perylene, perinone-based, porphyrin-based, Eu complex (Chem. Let
t. , 1267 (1991)) are known as red light emitting materials.

As a technique for obtaining red light emission, a method of mixing a small amount of a red fluorescent material as a dopant into a host material is also being studied. As the host material, tris (8-quinolinolato) aluminum complex, bis (1
0-benzoquinolinolato) beryllium complex, diarylbutadiene derivative, stilbene derivative, benzoxazole derivative, benzothiazole derivative and the like,
4- (dicyanomethylene)-as a dopant therein
2-methyl-6- (p-dimethylaminostyryl) -4
H-pyran, metal phthalocyanine (MgPc, AlPc
Cl), a squarylium compound and a biolanthrone compound were used to emit red light.

[0006]

However, conventional red light-emitting materials (host material and dopant material) have a wide peak width even if the emission peak wavelength exceeds 580 nm,
The color purity was poor, and beautiful red light emission could not be obtained. Also,
A rare-earth complex such as an Eu complex has a narrow emission peak width and can provide clean red light emission, but has a maximum luminance of several to several tens of cd / m.
^The problem was that clear display was not possible due to the low value of ² .

An object of the present invention is to solve such a problem and to provide a red light emitting device having high color purity.

[0008]

According to the present invention, there is provided an element in which a luminescent substance is present between an anode and a cathode and which emits light at a peak wavelength of 580 nm or more and 720 nm or less due to electric energy. A light-emitting element including a fluorescent compound having a wavelength of 540 nm to 720 nm and a fused ring derivative.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the anode 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.

The cathode is not particularly limited as long as it can efficiently inject electrons into the organic material layer.
Gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, calcium, magnesium, etc., and lithium, sodium for improving the electron injection efficiency and improving the device characteristics , Potassium, calcium, magnesium or alloys containing these low work function metals are effective. But,
These low work function metals are generally unstable in the air in many cases. For example, an organic layer is doped with a very small amount of lithium or magnesium (1 nm or less as indicated by a film thickness gauge by vacuum deposition) to have high stability. Although a method using an electrode can be mentioned as a preferable example, it is not particularly limited because an inorganic salt such as lithium fluoride can be used. In addition, platinum, gold,
Lamination of metals such as 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, and hydrocarbon polymers. Are preferred examples. 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.

The luminescent substance is defined as 1) a hole transport layer / a luminescent layer,
2) hole transport layer / light emitting layer / electron transport layer, 3) light emitting layer / electron transport layer, 4) hole transport layer / light emitting layer / hole blocking layer, 5)
A hole transporting layer / a light emitting layer / a hole blocking layer / an electron transporting layer; 6) a light emitting layer / a hole blocking layer / an electron transporting layer; Is also good. That is, as the element configuration, in addition to the multilayer laminated structure of the above 1) to 6), only a layer containing a luminescent material alone or a layer containing a luminescent material and a hole transporting material or an electron transporting material as in 7) may be provided. 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.

The hole transporting layer is formed of a hole transporting substance alone or a mixture of two or more substances or a mixture of a hole transporting substance and a polymer binder. N, N'-diphenyl-N, N'-di (3-methylphenyl) -4,4'-diphenyl-1,1'-diamine, N, N'-dinaphthyl-N, N'-diphenyl-
Triphenylamines such as 4,4′-diphenyl-1,1′-diamine, bis (N-allylcarbazole) or bis (N-alkylcarbazole), pyrazoline derivatives, stilbene compounds, hydrazone compounds, oxadi Heterocyclic compounds represented by azole derivatives, phthalocyanine derivatives, porphyrin derivatives, and polymer-based polycarbonates and styrene derivatives having the above monomers in the side chain, polyvinylcarbazole, polysilane, and the like are preferable. However, the compound is not particularly limited as long as it can inject holes from the anode and can transport holes.

The light-emitting material emits light at a peak wavelength of 580 nm to 720 nm due to electric energy. 58
If it is smaller than 0 nm, red light emission with good color purity cannot be obtained even if the peak width is narrow, and if it is larger than 720 nm, visibility deteriorates, and efficient high-brightness red light emission cannot be obtained.

The light emitting material has a fluorescence peak wavelength of 540.
As a preferable method, a doping method including a combination of a fluorescent compound having a wavelength of from nm to 720 nm and a condensed ring derivative, using the fluorescent compound as a host material and the condensed ring derivative as a dopant material can be mentioned. 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.

Energy transfer from the host material to the dopant material requires an overlap between the fluorescence spectrum of the host material and the absorption spectrum (excitation spectrum) of the dopant material. In addition, the Stokes shift (difference between the peak of the excitation spectrum and the peak of the fluorescence spectrum) of the dopant material having good color purity is as narrow as several to several tens of nm, so as to obtain high color purity red light emission from the dopant material of 580 nm to 720 nm. Then, the absorption spectrum (excitation spectrum) of the dopant material becomes yellow, yellow-orange, orange, red-orange, and red regions (540 nm or more and 720 nm or less). When the fluorescence spectrum of the host material is in the yellow-green, green, blue-green, blue, blue-violet, and violet regions on the shorter wavelength side than yellow and the spectrum overlap is small, energy transfer is not performed quickly, and the Light emission cannot be obtained, or even if light emission is obtained, light emission from the host material remains and red light emission of high color purity such as whitening cannot be obtained.

[0016] For the above reasons, 580 nm or more and 720
In order for the dopant material to emit light with high brightness and high color purity at nm or less, the host material needs to have a fluorescence peak wavelength of 540 nm or more and 720 nm or less. As a guide, those having fluorescence such as yellow, yellow-orange, orange, red-orange, and red correspond.

In order to obtain red light emission with good color purity, the emission peak wavelength is preferably longer than 590 nm, more preferably longer than 600 nm. More preferably, it is more preferably 610 nm or more. Therefore, it is desirable that the fluorescence peak wavelength of the host material be longer, and that the wavelength is longer than 560 nm and 720.
More preferably, it is not more than nm. 570 nm
More preferably, it is larger than 720 nm.

The fluorescence peak wavelength is 540 nm or more and 720 n
m or less, the basic skeleton of the host material is not particularly limited, but anthracene, pyrene, condensed ring derivatives such as perylene, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine, which have long been known as luminous bodies, Heterocyclic derivatives such as pyrimidine, thiophene and thioxanthene, quinolinol metal complexes such as tris (8-quinolinolato) aluminum complex, bipyridine metal complexes, rhodamine metal complexes, azomethine metal complexes, distyrylbenzene derivatives, tetraphenylbutadiene derivatives, stilbenes Derivatives, aldazine derivatives, coumarin derivatives, phthalimide derivatives, naphthalimide derivatives,
Azole derivatives such as perinone derivatives, pyrrolopyrrole derivatives, cyclopentadiene derivatives, imidazole derivatives and oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives and their metal complexes, merocyanine derivatives, porphyrin derivatives, and polyphenylene in the polymer system. Vinylene derivatives, polyparaphenylene derivatives, and polythiophene derivatives can be used. The fluorescence peak wavelength of the basic skeleton of the host material itself is 540 nm or more and 720 nm
However, if the fluorescence peak wavelength is 540 nm or less, or if it is desired to increase the wavelength for efficient energy transfer with the dopant, an aromatic ring or a heterocyclic ring is added to the basic skeleton. By introducing at least one of the rings as a substituent, or by condensing, or by replacing the ring structure contained in the basic skeleton of the fluorescent compound with a heterocyclic ring, it is possible to increase the wavelength, which is more suitable as a host material. Can be used. In the case where at least one of an aromatic ring and a heterocyclic ring is introduced as a substituent into the basic skeleton or condensed, introduction of the basic skeleton itself as a substituent and condensation thereof are also included.

Specifically, the following are mentioned. Condensed ring derivatives of anthracene derivatives, such as bis (cyanostyryl) anthracene derivatives, in which an aromatic ring is conjugated and a cyano group of an electron-withdrawing group is introduced, and carbazolyl vinyl, in which a heterocyclic ring is conjugated, is a pyrene derivative. Examples of the perylene derivative such as a pyrene derivative include a decacyclene derivative in which an aromatic ring is condensed, and a perylene dicarboxylic acid ester derivative in which a carboxylic acid ester group of an electron-withdrawing group is introduced. Heterocyclic derivatives of pyrazine derivatives include bisnaphthylvinylpyrazine derivatives, tristyrylpyrazine derivatives, and tetrapyridylvinylpyrazine derivatives in which a heterocyclic or aromatic ring is conjugated, and pentaphenylnaphthyridine derivatives in which an aromatic ring is introduced in a naphthyridine derivative. The quinoxaline derivatives include pyridoimidazoquinoxaline derivatives in which heterocycles are condensed, bistriphenylaminovinylquinoxaline derivatives in which aromatic rings are introduced, bispyrenylvinylquinoxaline derivatives in which aromatic rings are conjugated, bis (Phenylquinoxalyl) biphenyl derivatives, pyrimidine derivatives, pyrimidopyrimidine derivatives, etc. condensed themselves, thiophene derivatives, bisstyrylthiophene derivatives, in which aromatic rings are conjugated, self-conjugated Etc. linked thienyl derivatives. In the quinolinol metal complex, tris (5,7-bis (4-
Phenyl) -8-quinolinolato) aluminum complex, bis (5,7-bis (4-phenyl) -8-quinolinolato) zinc complex, tris (5,7-bis (4-fluorophenyl) -8-quinolinolato) aluminum complex , Bis (2-phenyl-8-quinolinolato) zinc complex, bis (2- (bithienylvinyl) -8-quinolinolato) zinc complex in which a heterocyclic ring or an aromatic ring is conjugated, bis (2- (thienylvinyl)) -8-quinolinolato) zinc complex, bis (2- (pyridylvinyl) -8-quinolinolato) zinc complex, bis (2-phenyl-8-quinolinolato) zinc complex, bis (2-styryl-8-quinolinolato) zinc complex, Benzo (f) quinolinol zinc complex having an aromatic ring condensed, acridine metal complex, tris (2-cyano 8-quinolinolato) aluminum complex, such as 2-cyano-8-quinolinolato tritium complexes. Examples of the bipyridyl metal complex include a biphenylphenanthroline metal complex in which an aromatic ring is condensed and an aromatic ring is further introduced. Examples of the distyrylbenzene derivative include a distyrylpyrazine derivative in which a benzene skeleton is substituted with a pyrazine skeleton. Examples of the stilbene derivative include a bistriazinyl stilbene derivative into which a heterocyclic ring has been introduced. Examples of the aldazine derivative include a bisnaphthyl aldazine derivative into which an aromatic ring has been introduced. Examples of the coumarin derivative include a dibenzotriazolyl coumarin derivative and a phenyloxadiazolyl coumarin derivative into which a heterocyclic ring has been introduced. Examples of the naphthalimide derivative include a tetraphenylcarboxylic acid dianilide derivative and a tetraphenylcarboxylic acid diimide derivative, which are condensed and linked, and a benzimidazolylbenzimidazopyridonaphthalimide derivative into which a heterocyclic ring is condensed and introduced. Examples of the perinone derivative include a dibenzoperinone derivative in which an aromatic ring is condensed, and a bisperinone derivative in which itself is conjugated. Examples of the pyrrolopyrrole derivative include a diphenylpyrrolopyrrole derivative into which an aromatic ring has been introduced. Cyclopentadiene derivatives include bis (bithiophenyl) diphenylsilacyclopentadiene derivatives and bis (benzothiophenylthiophenyl) tetraphenylsilacyclopentadiene derivatives in which the cyclopentadiene skeleton is replaced with a silacyclopentadiene skeleton and an aromatic or heterocyclic ring is introduced. No. Examples of the oxazole derivative include a bis (benzoxazolyl) ethylene derivative in which an aromatic ring is condensed and further conjugated to itself. Examples of the thiazole derivative include a phenylazobenzothiazole derivative in which an aromatic ring is condensed and an aromatic ring is conjugated. Examples of the oxadiazole derivative include a bis (anthracenyloxadiazolyl) benzene derivative and a tris (anthracenyloxadiazolyl) benzene derivative in which an aromatic ring is introduced and further conjugated to itself. Examples of the thiadiazole derivative include a bis (diphenylpyridinothiadiazolyl) benzene derivative in which a heterocyclic ring is condensed, an aromatic ring is further introduced, and the ring itself is conjugated. Examples of the merocyanine derivative include a dicyanomethylenepyran derivative into which a cyano group as an electron-withdrawing group is introduced. Although the above is specifically mentioned, the present invention is not limited to this.

Preferred examples of the dopant include fused ring derivatives. Here, in order to obtain high color purity red light emission of 580 nm or more and 720 nm or less, a condensed ring derivative in which seven or more ring structures are condensed is preferable in consideration of the length of the conjugate length.

Among the fused ring derivatives, the following general formula (1):
Those having a structure represented by the following general formula (2) or the following general formula (3) are preferably used.

[0022]

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Here, R ^{1 to} R ¹⁶ are hydrogen, alkyl,
Alkoxy, halogen, aryl, aralkyl, alkenyl, aryl ether, heterocycle, cyano, aldehyde, carbonyl, ester, carbamoyl, amino, condensed aromatic, aliphatic, or heterocyclic ring formed between adjacent substituents Selected from

[0024]

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Here, R ^{17 to} R ³² represent hydrogen, alkyl,
Alkoxy, halogen, aryl, aralkyl, alkenyl, aryl ether, heterocycle, cyano, aldehyde, carbonyl, ester, carbamoyl, amino, condensed aromatic, aliphatic, or heterocyclic ring formed between adjacent substituents Selected from

[0026]

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Here, R ^{33 to} R ⁴⁶ represent hydrogen, alkyl,
Alkoxy, halogen, aryl, aralkyl, alkenyl, aryl ether, heterocycle, cyano, aldehyde, carbonyl, ester, carbamoyl, amino, condensed aromatic, aliphatic, or heterocyclic ring formed between adjacent substituents Selected from

In the description of these substituents, the alkyl group means a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, a propyl group and a butyl group, which may be unsubstituted or substituted. Absent. 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. Halogen refers to fluorine, chlorine, bromine and iodine. Further, the aryl group is, for example, a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group,
It represents an aromatic hydrocarbon group such as a terphenyl group and a pyrenyl group, 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 refers to an unsaturated aliphatic hydrocarbon group containing a double bond such as a vinyl group, an allyl group and a butadienyl group, which may be unsubstituted or substituted. 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. Also,
The heterocyclic group is, for example, a thienyl group, a furyl group, a pyrrolyl group, an imidazolyl group, a pyrazolyl group, an oxazolyl group,
A cyclic structure group having an atom other than carbon, such as a pyridyl group, a pyrazyl group, a pyrimidyl group, a quinolinyl group, an isoquinolyl group, a quinoxalyl group, an acridinyl group, and a carbazolyl group, may be unsubstituted or substituted. Aldehyde, carbonyl, ester, carbamoyl, 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 condensed ring and the aliphatic ring formed between the adjacent substituents are, for example, those forming a conjugated or non-conjugated condensed ring at adjacent positions such as R ¹ and R ² . These condensed rings may contain nitrogen, oxygen and sulfur atoms in the ring structure, or may be condensed with another ring.

In order to obtain red light emission with good color purity, it is preferable to increase the wavelength of the fused ring derivative. In order to increase the wavelength, it is preferable to introduce an electron-withdrawing group or extend the conjugation.

Examples of the electron-withdrawing group include a cyano group, a halogen and a carbonyl group, and among them, a cyano group and a carbonyl group are preferable. These electron-withdrawing groups may be introduced alone, in combination, directly or via a conjugated group.

In order to increase the wavelength, it is more preferable to extend the conjugate, and it is more preferable to extend the conjugate by introducing a conjugated group or condensing.

In introducing a conjugated group, a substituted or unsubstituted vinyl group such as a vinyl group, a phenylethylene group or a diphenylethylene group, a substituted or unsubstituted aromatic ring such as a phenyl group, a biphenyl group or a naphthyl group, or a thienyl group Or a substituted or unsubstituted heterocycle such as a furyl group or a pyridyl group. These conjugate groups may be introduced alone or in combination.

The expansion of conjugation by condensation includes forming a condensed aromatic ring or a condensed heterocyclic ring with an adjacent substituent. These expansions of conjugation by condensation may be used alone or in combination. The above methods for increasing the wavelength may be used alone or in combination.

Specific examples of the above fused ring derivative include the following structures.

[0035]

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[0036]

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[0037]

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When the doping amount is usually too large, a concentration quenching phenomenon occurs.
It is preferably used in the following, more preferably 2% or less. As a doping method, it can be formed by a co-evaporation method with a host material, but it may be mixed with the host material in advance and then evaporated at the same time. In addition, since the fused ring derivative emits light even in a very small amount, a small amount of the fused ring derivative can be sandwiched between host materials for use. In this case, one or more layers may be stacked with the host material.

The dopant material to be added to the light emitting material is not limited to one kind of the compound having the above-mentioned condensed ring derivative, and a plurality of the above compounds may be used as a mixture, or one or more kinds of known dopant materials may be used. It may be used as a mixture with a compound. Specifically, conventionally known naphthalimide derivatives such as bis (diisopropylphenyl) perylenetetracarboxylic imide, perinone derivatives,
Rare earth complexes such as Eu complexes having acetylacetone or benzoylacetone and phenanthroline as ligands;
-(Dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran and its analogs, metal phthalocyanine derivatives such as magnesium phthalocyanine and aluminum chlorophthalocyanine, rhodamine compounds, deazaflavin derivatives, coumarin derivatives, oxazines Compounds and the like can coexist, but are not particularly limited thereto.

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 quinolinol derivative metal complexes represented by 8-hydroxyquinoline aluminum, tropolone metal complexes, flavonol metal complexes, perylene derivatives, perinone derivatives, naphthalene,
There are coumarin derivatives, oxadiazole derivatives, aldazine derivatives, bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, and the like, but are not particularly limited. Although these electron transport materials are used alone,
They may be laminated or mixed with different electron transport 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.

The method for forming the luminescent material is not particularly limited, such as resistance heating evaporation, electron beam evaporation, sputtering, molecular lamination, and coating. However, resistance heating evaporation and electron beam evaporation are usually used in terms of characteristics. preferable. 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 order to provide a beautiful red display, the peak wavelength of the emission spectrum is in the range of 580 nm to 720 nm, preferably 590 nm to 710 nm, more preferably 600 nm to 700 nm, and still more preferably 610 nm to 690 nm. It is important that the half width is 100 nm or less. The emission spectrum is preferably a single peak as much as possible. In some cases, the emission spectrum may have a plurality of maximum points due to overlap with another peak, or a shoulder may appear at the foot of the peak. In the present invention, the peak wavelength is defined as the wavelength of the main peak corresponding to the emission center wavelength, and the half-value width is defined as the peak width at half the height of the emission center wavelength in all of these peaks.

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 the voltage value are not particularly limited. However, in consideration of the power consumption and life of the device, it is necessary to obtain the maximum luminance with the lowest possible energy.

The matrix in 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, a square pixel having a side of 300 μm or less is usually used for displaying images and characters on a personal computer, a monitor, and a television. In the case of a large display such as a display panel, a pixel having a side of mm order 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 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.

The segment type in the present invention means that a pattern is 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.

The backlight in the present invention is mainly used for the purpose of 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.

[0048]

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 1 × 10 ⁻⁵ Pa or less. By the resistance heating method, first, N, N'-
Diphenyl-N, N '-(3-methylphenyl) -1,
1′-diphenyl-4,4′-diamine (TPD)
00 nm was deposited. Next, Tris (5,
7-bis (4-fluorophenyl) -8-quinolinolato) aluminum complex (fluorescence peak wavelength 559 nm)
Is used as a dopant material for the following fused ring derivative (D1)
Using (fluorescence peak wavelength of 610 nm), co-evaporation was performed to a thickness of 50 nm so that the dopant became 1 wt%, and a host material was stacked to a thickness of 50 nm. Next, lithium was deposited to a thickness of 0.2 nm and silver to a thickness of 150 nm to form a cathode, and 5 × 5
An mm square device was produced. The emission peak wavelength of this light-emitting device was 610 nm, and it emitted beautiful red light.

[0050]

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Example 2 The following condensed ring derivative (D2) (having a fluorescent peak wavelength of 670 nm) was used as a dopant material, and bis (2- (bithienylvinyl) -8-quinolinolato) zinc complex (having a fluorescent peak wavelength of 591 nm) was used as a host material. A light emitting device was produced in the same manner as in Example 1 except that was used. The emission peak wavelength of this light-emitting element was 670 nm, and it emitted beautiful red light.

[0052]

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Example 3 A light emitting device was manufactured in the same manner as in Example 1 except that the following perinone derivative (fluorescence peak wavelength: 580 nm) was used as a host material. The emission peak wavelength of this light emitting device is 61
0 nm, and showed a beautiful red light emission.

[0054]

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Example 4 A light emitting device was produced in the same manner as in Example 2 except that the following perinone derivative (fluorescence peak wavelength: 600 nm) was used as a host material. The emission peak wavelength of this light emitting device is 67
0 nm, and showed a beautiful red light emission.

[0056]

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Example 5 The procedure of Example 2 was repeated except that bis (2 ′, 6′-diisopropylanilide) perylene-3,4,9,10-tetracarboxylic acid (fluorescence peak wavelength: 620 nm) was used as the host material. Thus, a light-emitting element was manufactured. The emission peak wavelength of this light-emitting element was 670 nm, and it emitted beautiful red light.

Example 6 A light emitting device was manufactured in the same manner as in Example 1 except that N- (dimethylphenyl) -naphthalimide (fluorescence peak wavelength: 590 nm) was used as a host material. The emission peak wavelength of this light-emitting device was 610 nm, and it emitted beautiful red light.

Example 7 3,6-Diphenyl-2,5-dihydro-as a host material
A light emitting device was manufactured in the same manner as in Example 1 except that 2,5-dimethylpyrrolo [3,4-c] pyrrole-1,4-dione (orange fluorescence) was used. The emission peak wavelength of this light emitting device is 61
0 nm, and showed a beautiful red light emission.

Example 8 3,8-dimethylpyrido [1 ′,
A light-emitting element was produced in the same manner as in Example 1 except that 2 ': 1,2] imidazo [4,5-b] quinoxaline (yellow fluorescence) was used. The emission peak wavelength of this light emitting device is 61
0 nm, and showed a beautiful red light emission.

Example 9 A light emitting device was produced in the same manner as in Example 1 except that the following quinoxaline derivative (fluorescence peak wavelength: 575 nm) was used as a host material. The emission peak wavelength of this light-emitting device was 610 nm, and it emitted beautiful red light.

[0062]

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Example 10 The following quinoxaline derivative (orange fluorescence) as a host material
A light-emitting element was manufactured in the same manner as in Example 2 except for using. The emission peak wavelength of this light-emitting element was 670 nm, and it emitted beautiful red light.

[0064]

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Example 11 As a host material, 2,3,5,6-tetrakis [2-
A light emitting device was produced in the same manner as in Example 1 except that (phenyl) vinyl] pyrazine (yellow fluorescence) was used. The emission peak wavelength of this light-emitting device was 610 nm, and it emitted beautiful red light.

Example 12 A light emitting device was produced in the same manner as in Example 1 except that the following styrylthiophene derivative (fluorescence peak wavelength: 550 nm) was used as a host material. The emission peak wavelength of this light-emitting device was 610 nm, and it emitted beautiful red light.

[0067]

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Example 13 As a host material, 5,5 ″ -bis {4- [bis (4-methylphenyl) amino] phenyl} -2,2 ′: 5 ′,
A light-emitting device was produced in the same manner as in Example 1 except that 2 ″ -terthiophene (fluorescence peak wavelength: 570 nm) was used, and the light-emitting peak wavelength of this light-emitting device was 610 nm, and it emitted beautiful red light.

Example 14 1,1-dimethyl-2,5-bis (5
-T-butyldiphenylsilyl-2-thienyl) -3,
A light emitting device was manufactured in the same manner as in Example 1 except that 4-diphenylsilacyclopentadiene (fluorescence peak wavelength: 551 nm) was used. The emission peak wavelength of this light emitting device is 6
It was 10 nm and showed a beautiful red emission.

Example 15 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 30 × 40 mm, and a 300 μm pitch (remaining width of 270 μm) was obtained by photolithography. ) X 32 stripes were patterned. One side of the long side of the ITO stripe is used to facilitate electrical connection with the outside.
It is expanded to a pitch of 27 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.
Evacuation was performed until the pressure became × 10 ⁻⁴ Pa or less. First, 100 nm of N, N′-diphenyl-N, N ′-(3-methylphenyl) -1,1′-diphenyl-4,4′-diamine (TPD) was deposited by a resistance heating method. Next, tris (5,7-bis (4-fluorophenyl) -8-quinolinolato) aluminum complex is used as a host material, and D1 is used as a dopant material. And change the host material to 5
It was laminated to a thickness of 0 nm. Next, a mask provided with 16 openings of 250 μm (corresponding to a remaining width of 50 μm and a pitch of 300 μm) provided on a 50 μm-thick Kovar plate by wet etching is exchanged in a vacuum so as to be orthogonal to the ITO stripes. It was fixed with a magnet from the back so that the and the ITO substrate were in close contact. And 5 of magnesium
0 nm, 150 nm of aluminum is evaporated to 32 × 16
A dot matrix device was manufactured. When this device was driven in a matrix, characters could be displayed without crosstalk.

[0071]

According to the present invention, it is possible to provide a red light emitting device having high utilization efficiency of electric energy and excellent color purity.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C07D 471/04 120 C07D 471/04 120 471/06 471/06 F term (Reference) 3K007 AB03 AB04 BA06 CA01 CB01 DA01 DB03 DC00 EB00 4C023 CA04 4C065 AA01 AA03 AA05 BB06 BB12 CC01 CC09 DD02 DD03 EE02 HH01 JJ01 JJ04 KK01 KK05 LL01 PP01 PP05

Claims (8)

[Claims] 1. A luminescent substance exists between an anode and a cathode, and a peak wavelength of 580 nm or more and 720 n is determined by electric energy.
m, wherein the device contains at least a fluorescent compound having a fluorescent peak wavelength of 540 nm to 720 nm and a condensed ring derivative. 2. The light emitting device according to claim 1, wherein the fused ring derivative is represented by the following general formula (1). Embedded image (Where R ^{1 to} R ¹⁶ are hydrogen, alkyl, alkoxy, halogen, aryl, aralkyl, alkenyl, aryl ether, heterocyclic, cyano, aldehyde, carbonyl, ester, carbamoyl, amino, It is selected from aromatic, aliphatic and heterocyclic condensed rings to be formed.) 3. The light emitting device according to claim 1, wherein the fused ring derivative is represented by the following general formula (2). Embedded image (Where R ^{17 to} R ³² are hydrogen, alkyl, alkoxy, halogen, aryl, aralkyl, alkenyl, aryl ether, heterocyclic, cyano, aldehyde, carbonyl, ester, carbamoyl, amino, It is selected from aromatic, aliphatic and heterocyclic condensed rings to be formed.) 4. The light emitting device according to claim 1, wherein the fused ring derivative is represented by the following general formula (3). Embedded image (Where R ^{33 to} R ⁴⁶ are hydrogen, alkyl, alkoxy, halogen, aryl, aralkyl, alkenyl, aryl ether, heterocyclic, cyano, aldehyde, carbonyl, ester, carbamoyl, amino, It is selected from aromatic, aliphatic and heterocyclic condensed rings to be formed.) 5. The condensed ring derivative according to claim 1, wherein at least one of a vinyl group, an aromatic ring and a heterocyclic ring is introduced as a substituent into the basic skeleton of the condensed ring derivative. 2. The light-emitting device according to claim 1, wherein at least one of the ring structure contained in the skeleton is substituted with a heterocyclic ring. 6. The fluorescent compound, wherein at least one of a vinyl group, an aromatic ring, and a heterocyclic ring is introduced as a substituent into the basic skeleton of the fluorescent compound, is condensed, or is included in the basic skeleton of the fluorescent compound. The light-emitting device according to claim 1, wherein at least one of the ring structures substituted by a heterocyclic ring is performed. 7. The light emitting device according to claim 1, wherein said fused ring derivative is a dopant material. 8. The light-emitting device according to claim 1, wherein the light-emitting device is a display for displaying by a matrix and / or segment method.