JPH11279426A - Rhodamine dye, color conversion film and organic electroluminescence device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rhodamine-based dye capable of converting blue light to red with high efficiency, and a color conversion film using the dye, in order to realize full-color organic EL elements, and Provide organic EL devices. SOLUTION: General formula (I) [Wherein, at least one of R ¹ to R ⁶ is a sterically hindered group that inhibits formation of an aggregate, X is O or S,
A represents a counter ion. A color conversion film comprising a rhodamine dye represented by formula (I) and a dye represented by formula (I) in a resin, and at least an organic compound layer comprising a light emitting layer represented by formula (I): An organic electroluminescence device comprising a dye.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rhodamine-based dye capable of emitting red light with high efficiency when used in an organic electroluminescence (hereinafter sometimes abbreviated as "organic EL") element, and to use this dye. The present invention relates to a color conversion film and an organic EL device.

[0002]

2. Description of the Related Art An organic EL device is a completely solid-state device, has excellent visibility, can be reduced in weight and thickness, and can have a voltage of several volts (hereinafter, referred to as an organic EL device).
(V may be abbreviated to V), so that it can be applied to a display, and therefore research is being actively conducted at present. The biggest problem when using an organic EL element as a display is the development of a method for full-color display. To realize this full color display,
Emission of the three primary colors of green and red must be finely arranged in a two-dimensional direction, but the following methods are currently proposed.

The three-color array method, the color filter method, and the color conversion film method The above-mentioned method is a method in which one color pixel is formed by three pixels using light sources of three primary colors, but the organic EL element is subjected to wet patterning. Therefore, there is a disadvantage that it is difficult to produce a high-definition display.

The above-mentioned method is a method in which color conversion is performed by a color filter using a white light source to obtain three primary colors. This method is easy to pattern, but has the disadvantage that the luminance of each color obtained is significantly lower than the luminance of the white light source. The above method is similar to the above method, but is characterized in that blue light is used as a light source. In this method, green and red light is emitted by the fluorescence of the dye excited by the blue light, which is the light source. Therefore, there is an advantage that loss of luminance is smaller than that of the color filter method.

Among the above methods, the color conversion film method has been studied as a method for achieving full color organic EL elements. However, this method has a low conversion efficiency from blue to red and is practical. Was not. Further, when an organic EL element is used for a full-color display, it is difficult to independently emit red light having a high efficiency equivalent to that of blue and green, and development of such a red light-emitting material has been desired.

[0006]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned problems of the prior art and converts blue light to red with high efficiency in order to realize a full color organic EL device. An object of the present invention is to provide a possible rhodamine-based dye, and a color conversion film and an organic EL device using the dye.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, introduced a sterically hindered group into the molecule of a rhodamine dye to suppress the association of the dye. It has been found that this makes it possible to convert blue light into red with high efficiency. The present invention has been completed based on such findings, and the gist is as follows.

[0008]

(1) A rhodamine dye having at least one sterically hindered group in a molecule that inhibits formation of an aggregate. (2) The rhodamine dye according to (1), wherein the sterically hindered group is any of the following substituents: A long-chain substituent having 6 or more main chain atoms, a substituent having at least one quaternary carbon atom, having at least one unsaturated bond in the main chain, and having at least one carbon atom having the unsaturated bond. A substituent bound to two substituents having 6 or more nuclear atoms, a substituent having at least 3 or more halogen atoms

(3) A dye represented by the general formula (I). [Wherein, at least one of R ^{1 to} R ⁶ is a sterically hindered group that inhibits formation of an aggregate, X is O or S, and A
Represents a counter ion. (4) In formula (I), R ¹ which is not a sterically hindered group
To R ⁶ are each independently hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, nuclei aryl group having 6 to 24 carbon atoms, a hydroxyl group, an amino group, a halogen group,
The dye according to the above (3), which is a nitro group, a cyano group, an amide group, a carboxyl group, an ester group, or a sulfone group.

(5) A dye represented by the general formula (II). [Wherein, R¹~ R⁶At least one of the following
Any substituent, X is O or S, and A is
Represents a counter ion. A long-chain substituent having 6 or more atoms in the main chain, a substituent having at least one quaternary carbon atom, having at least one unsaturated bond in the main chain,
At least two carbon atoms with unsaturated bonds
Substituent bonded to a substituent having 6 or more substituents Substitution having at least 3 halogen atoms
Base. (6) In the general formula (II), any of
R which is not a substituent¹~ R ⁶Are each independently hydrogen, carbon number
Alkyl group having 1 to 5, alkoxy group having 1 to 4 carbon atoms, nucleus
Aryl group having 6 to 24 carbon atoms, hydroxyl group, amino
Group, halogen group, nitro group, cyano group, amide group,
A boxyl group, an ester group, or a sulfone group,
The dye according to (5).

(7) A color conversion film obtained by dispersing the dye according to any one of (1) to (6) in a resin. (8) An organic electroluminescence device comprising an organic compound layer having at least an organic light-emitting layer sandwiched between a pair of electrodes, wherein the organic compound layer contains the dye according to any one of (1) to (6).

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a color conversion film characterized in that a rhodamine dye having at least one sterically hindered group is dispersed in a resin. Specifically, it is a color conversion film characterized by dispersing at least a rhodamine-based dye having a specific molecular structure represented by the general formula (I) in a resin. Note that a color conversion film is a film that emits light when excited by a light source.

It is generally known that when a dye is dispersed at a high concentration in a solution or a resin, the dye molecules form an association with each other and the fluorescence is remarkably reduced. This phenomenon is called concentration quenching. In order to suppress such concentration quenching, association of the dye can be suppressed by introducing a group having a steric hindrance function into the rhodamine-based dye molecule. That is, the feature of the rhodamine dye of the present invention is that it has at least one sterically hindered group in the general formula (I), and at least one of R ^{1 to} R ⁶ may be a sterically hindered group. .

As such a sterically hindered group, it has been found that substituents selected from the following are preferable. The substituents may be the same or different from each other. A long-chain substituent having 6 or more atoms in the main chain, a substituent having at least one quaternary carbon atom, having at least one unsaturated bond in the main chain, and a carbon atom having the unsaturated bond is A substituent bonded to at least two substituents having 6 or more nuclear atoms, a substituent having at least 3 halogen atoms, and excluding hydrogen atoms counted from atoms directly bonded to the rhodamine skeleton. The skeleton connected to the most atoms by a chemical bond is defined as the main chain of the substituent.

The number of atoms in the main chain is usually from 6 to 30, preferably from 10 to 30. Specific examples include n-hexyl, n-decanyl, n-octadecanyl, ethoxypropyl, n-butyl ester, N, N-
Substituents such as di- (n-butyl) amide and n-pentyloxy are exemplified. The number of the quaternary carbon is usually 1 to
10, preferably 1 to 6. Specific examples thereof include t-butyl, adamantyl, t-butoxy and t-butyl.
Substituents such as butylamide and t-butyl ester are exemplified.

The number of unsaturated bonds in the main chain is usually from 1 to 5, preferably from 1 to 3. The carbon atom having the unsaturated bond is usually bonded to 1 to 3 substituents having 6 or more nuclear atoms. Specific examples thereof include 2,2-diphenylvinyl, 1,2-diphenylvinyl, 4,4-diphenyl-1,3-butadiene and the like.

The number of the halogen atoms is usually 3 to 5
0, preferably 10 to 50, and more preferably 20 to 50. Specific examples include trifluoromethyl, trichloromethyl, perfluorol groups and the like. Next, R ^{1 to} R ⁶ when they are not sterically hindered groups will be described. In the formula, R ^{1 to} R ⁶ are hydrogen and have 1 to 5 carbon atoms.
Or an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 to 24 nuclear carbon atoms, a hydroxyl group, an amino group, a halogen group, a nitro group, a cyano group, an amide group, a carboxyl group, an ester group, and a sulfone group Selected from.

Specific examples of the alkyl group having 1 to 5 carbon atoms include methyl, ethyl, n-propyl, propyl and n-
Butyl, s-butyl, t-butyl, n-pentyl and the like. Specific examples of the alkoxy group having 1 to 4 carbon atoms include methoxy, ethoxy, n-propyloxy, i-propyloxy, n-butoxy, s-butoxy, and t-butoxy.

Specific examples of the aryl group having 6 to 24 core carbon atoms include a phenyl group, a biphenyl group, a tyl group, an anthranyl group, a terphenyl group, a pyrenyl group and the like. In addition, these aryl groups have 1 to 5 carbon atoms as described above.
May be substituted by an alkyl group or an alkoxy group having 1 to 4 carbon atoms. Specific examples of the halogen group include fluorine, chlorine, bromine and iodine.

In the general formulas (I) and (II),
X is a linking group and is represented by O or S. Also general
In the formulas (I) and (II), A is a counter ion
Yes, F^-, Cl^-, Br^-, I^-, ClO_Four ^-, BF
_Four ^-, ZnCl_Four ^2-, BPh _Four ^-And so on. General formula
Specific examples of the rhodamine dye (I) are shown below.

[0021]

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[0022]

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[0023]

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[0024]

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In the color conversion film of the present invention, the rhodamine dye of the general formula (I) is dispersed in the resin, but other dyes may be dispersed together. Specific examples thereof include coumarin dyes, perylene dyes, phthalocyanine dyes, stilbene dyes, cyanine dyes, polyphenylene dyes, and rhodamine dyes other than the general formula (I). The concentration of these dyes in the resin is from 0.01 to
It is preferably 10% by weight, more preferably 0.1 to 5% by weight.

The resin in which these dyes are dispersed is preferably transparent (having a transmittance of light in the visible light region of 50% or more) and having a small coefficient of thermal expansion. The color conversion film is patterned and separated in a plane. Therefore, a photosensitive resin to which a photolithography method can be applied is preferable. As a material that satisfies such conditions, for example, a photocurable resist material having a reactive vinyl group such as an acrylic acid type, a methacrylic acid type, a polyvinyl cinnamate type, and a ring rubber type may be used. When a printing method is used, a printing ink (medium) using a transparent resin is selected. For example, polyvinyl chloride resin,
Melamine resin, phenol resin, alkyd resin, epoxy resin, polyurethane resin, polyester resin, maleic acid resin, polyamide resin oligomer or polymer, polymethyl methacrylate, polyacrylate, polycarbonate, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose, etc. Can be used. Other examples include aromatic sulfonamide resins, urea resins, and benzoguanamine resins.

These resins may be used alone or as necessary.
You may mix and use 2 or more types. In the color conversion film of the present invention, the above-mentioned dye is dispersed in a resin, and this is formed on a light-transmitting substrate, but the method for forming the film is not particularly limited. Specific examples include a casting method, a spin cloth method, a vapor deposition method, an electrolytic method, a printing method, and the like. In general, a spin coating method is preferable.

The thickness of the color conversion film formed by the above-mentioned method must be appropriately selected for converting incident light into a desired wavelength, but is preferably in the range of 1 to 100 μm. More preferably, it is selected in the range of 1 to 20 μm.
The light-transmitting substrate used for forming the color conversion film of the present invention is preferably a smooth substrate having a transmittance of light of at least 50% in a visible light region of 400 to 700 nm of 50% or more. Specific examples include a glass substrate and a polymer plate.
As glass plates, especially soda-lime glass, barium
Strontium-containing glass, lead glass, aluminum silicate glass, borosilicate glass, barium borosilicate glass,
Quartz and the like can be mentioned. As the polymer plate, polycarbonate, acrylic, polyethylene terephthalate,
Examples include polyether sulfide, polysulfone, and the like.

This color conversion film is used when a display using an organic EL element is made full-color, and an organic EL element is used as a light source. However, the light source is not particularly limited thereto. For example, an LED, a cold cathode tube, an inorganic EL , Fluorescent lamps, incandescent lamps and the like may be used. In order to improve the quality of light transmitted through the color conversion film, high definition can be achieved by providing a color filter for converting a desired wavelength and adjusting the color purity. Such color filters include, for example, perylene pigments, lake pigments, azo pigments, quinacridone pigments, anthraquinone pigments, anthracene pigments, isoindoline pigments, isoindolinone pigments, phthalocyanine pigments, Phenylmethane-based basic dyes, indanthrone-based pigments, indophenol-based pigments, cyanine-based pigments, dioxazine-based pigments, etc., and only a dye consisting of a mixture of at least two types, or a dye in a binder resin Examples thereof include those in a dissolved solid state.

As a configuration using the color conversion film of the present invention,
Examples include the following: Light source / Color conversion film Light source / Transparent substrate / Color conversion film Light source / Color conversion film / Transparent substrate Light source / Transparent substrate / Color conversion film / Transparent substrate Light source / Color conversion film / Color filter Light source / Light-transmitting substrate / color conversion film / color filter Light source / color conversion film / light-transmitting substrate / color filter Light source / light-transmitting substrate / color conversion film / light-transmitting substrate / color filter Light source / light-transmitting substrate / color Conversion membrane / color filter /
Translucent Substrate (10) Light Source / Color Conversion Film / Color Filter / Translucent Substrate In the above-exemplified configuration, each component may be sequentially laminated or bonded. As a result, the order of bonding is not particularly limited, and those bonded together can be freely selected as long as desired performance is not impaired.

The present invention provides an organic EL device characterized in that a rhodamine-based dye having at least one sterically hindered group is contained in a light-emitting layer or the like of the organic EL device. Specifically, the organic EL device is characterized in that a specific rhodamine-based dye represented by the general formula (I) is contained in a light emitting layer of the organic EL device. The configuration, material, and the like used when manufacturing the organic EL element by incorporating the present dye may be the same as the configuration and material conventionally used when manufacturing the organic EL element.

Hereinafter, the specific structure and material will be described. [Structure of Organic EL Element] A typical example of the structure of the organic EL element used in the present invention will be described below, but the present invention is not limited thereto. Specifically, anode / light emitting layer / cathode anode / hole injection layer / light emitting layer / cathode anode / light emitting layer / electron injection layer / cathode anode / hole injection layer / light emitting layer / electron injection layer / cathode anode / organic Semiconductor layer / light emitting layer / cathode anode / organic semiconductor layer / electron barrier layer / light emitting layer / cathode anode / organic semiconductor layer / light emitting layer / adhesion improving layer / cathode anode / hole injection layer / hole transport layer / light emitting layer / Examples of the structure include an electron injection layer / a cathode. Then, such an organic EL element is manufactured on a light-transmitting substrate described below.

The specific rhodamine dye represented by the general formula (I) is contained in any one of these constituent elements. The amount to be contained is selected from 0.01 to 50 mol%, and is particularly preferably 0.01 to 10 mol%. This content is a value in only the layer containing the rhodamine dye.

[Translucent Substrate] As described above, the translucent substrate is a substrate that supports the organic EL element.
It is preferable that the substrate has a transmittance of light of 50% or more in a visible light region of 0 to 700 nm and a smooth surface. Specific examples include a glass plate and a polymer plate. Examples of the glass plate include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone.

[Anode] As the anode, a metal, an alloy, an electrically conductive compound having a high work function (4 eV or more), or a mixture thereof is preferably used as an electrode material. Specific examples of such an electrode material include metals such as Au, and conductive materials such as CuI, ITO, SnO2, and ZnO. Then, a thin film is formed from these electrode materials by a method such as a vapor deposition method or a sputtering method to form an anode.

When light emission of the light emitting layer is extracted from the anode formed as described above, it is preferable that the light transmittance of the anode be greater than 10%. Similarly, the sheet resistance of the anode is preferably several hundred Ω / □ or less. In order to ensure the above performance, the thickness of the anode is usually 10 nm to 1 μm, preferably 10 nm, although it depends on the material of the anode.
It is selected in the range of ２００200 nm.

[Light Emitting Layer] The light emitting layer of the organic EL device has the following functions. That is, an injection function; a function of injecting holes from an anode or a hole injection layer when an electric field is applied, and of injecting electrons from a cathode or an electron injection layer. Transport function; injected charges (electrons and holes) The function of moving an electron by the force of an electric field. Light-emitting function; a function of providing a field for recombination of electrons and holes, and connecting it to light emission.

However, there may be a difference between the ease of injecting holes and the ease of injecting electrons, and the transport ability represented by the mobility of holes and electrons may be large or small. It is preferable to transfer one of the charges. Next, the light-emitting material of the light-emitting layer of the organic EL element is mainly an organic compound, and a compound to be used is selected according to a desired color tone. From this viewpoint, the relationship between the color tone and the compound is specifically classified as follows.

[0039]

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First, in the case of obtaining violet light emission from the ultraviolet region, compounds represented by the following general formula can be mentioned. In this general formula, X represents the following compound.

[0041]

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Here, n is 2, 3, 4, or 5. Y represents the following compound.

[0043]

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Phenyl group, phenylene group,
A naphthyl group having an alkyl group having 1 to 4 carbon atoms, an alkoxy group, a hydroxyl group, a sulfonyl group, a carbonyl group, an amino group,
A dimethylamino group, a diphenylamino group or the like may be used alone or plurally. These may be combined with each other to form a saturated 5-membered ring or 6-membered ring.
Further, a phenyl group, a phenylene group, or a naphthyl group bonded at the para position is preferable for forming a smooth vapor-deposited film because it has good binding to a light-transmitting substrate.

Specifically, the following compounds are used. In particular, p
-Quarterphenyl derivatives and p-quinkphenyl derivatives are preferred.

[0046]

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[0047]

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Next, in order to obtain blue to green light emission, for example, benzothiazole-based, benzimidazole-based, benzoxazole-based fluorescent whitening agents, metal-chelated oxinoid compounds, and styrylbenzene-based compounds can be mentioned. . Specific examples of the compound name include those disclosed in JP-A-59-194393. In addition, other useful compounds are described in Chemistry of Synthetic Soy, 1971,62.
Listed on pages 8-637 and 640.

As the chelated oxinoid compound, for example, those disclosed in JP-A-63-295695 can be used. A typical example is tris (8-quinolinol) aluminum (hereinafter referred to as A
8-hydroxyquinoline-based metal complex such as 1q) and dilithium epthridione. Examples of the styrylbenzene-based compound include, for example, European Patent No. 0319881 and European Patent No. 0.
The one disclosed in the specification of Japanese Patent No. 373582 can be used.

Further, a distyrylpyrazine derivative disclosed in JP-A-2-252793 can also be used as a material for the light emitting layer. As other materials, for example, a polyphenyl-based compound disclosed in European Patent No. 0377715 can also be used as a material for the light-emitting layer. Further, in addition to the above-described fluorescent brightener, metal chelated oxinoid compound, styrylbenzene-based compound and the like, for example, 12-phthaloperinone (J. Appl.
hys., Vol. 27, L713 (1988)), 1, 4
-Diphenyl-1,3-butadiene, 1,1,4,4-
Tetraphenyl-1,3-butadiene (Appl.
Phys. Lett., Vol. 56, L799 (1990)
Year)), a naphthalimide derivative (JP-A-2-30588)
No. 6), perylene derivatives (JP-A-2-189890)
), Oxadiazole derivatives (JP-A-2-216)
No. 791, or an oxadiazole derivative disclosed by Hamada et al. At the 38th Lecture Meeting on Applied Physics, an aldazine derivative (JP-A-2-220393), and a pyrazirine derivative (JP-A-2-220394). ), Cyclopentadiene derivatives (JP-A-2-2896)
No. 75), pyrrolopyrrole derivatives (JP-A-2-29)
No.6891), styrylamine derivatives (Appl.
Phys. Lett., Vol. 56, L799 (1990)
Coumarin compounds (JP-A-2-191694), International Patent Publication WO90 / 13148 and Appl.
Phys. Lett., Vol 58, 18, P1982.
(1991) can also be used as a material for the light emitting layer.

In the present invention, an aromatic dimethylidin compound (European Patent No. 0388768) is particularly used as a material for the light emitting layer.
It is preferable to use those disclosed in Japanese Patent Application Laid-Open No. HEI 3-231970. As a specific example,
4'-bis (2,2-di-t-butylphenylvinyl)
Biphenyl, (hereinafter abbreviated as DTBPBBi),
4,4′-bis (2,2-diphenylvinyl) biphenyl (hereinafter abbreviated as DPVBi) and the like and derivatives thereof can be given.

Further, Japanese Patent Application Laid-Open No. Hei 5-258862 discloses
General formula (Rs-Q) described _Two-Al-OL
In the above formula, L is phenyl
A hydrocarbon comprising 6 to 24 carbon atoms comprising
Where OL is a phenolate ligand and Q is a substituted 8-
Represents a quinolinolate ligand, and Rs is an aluminum atom
Has more than two substituted 8-quinolinolato ligands
8-quinolinola chosen to sterically hinder
Represents a ring substituent). Specifically, bis (2-methyl
-8-quinolinolate) (para-phenylphenolate)
G) Aluminum (III) (hereinafter PC-7), screws
(2-Methyl-8-quinolinolate) (1-Naphtholar
G) Aluminum (III) (hereinafter PC-17)
I can do it.

In addition, there is a method of obtaining mixed blue and green light emission with high efficiency by using doping according to Japanese Patent Application Laid-Open No. 6-9953. In this case, as the host, the above-mentioned luminescent material can be used, and as the dopant, a strong fluorescent dye from blue to green, for example, a coumarin-based fluorescent dye or a fluorescent dye similar to that used as the above-mentioned host can be used.

Specifically, a luminescent material having a distyrylarylene skeleton, particularly preferably DPVBi, is used as a host, and diphenylaminovinylarylene is used as a dopant.
Particularly preferred is, for example, N, N-diphenylaminovinylbenzene (DPAVB). The light-emitting layer that emits white light is not particularly limited, and examples thereof include the following.

An element utilizing tunnel injection as in the case of an element using the tunnel injection as in the example in which the energy level of each layer of the organic EL laminated structure is defined and light is emitted using tunnel injection (European Patent No. 0390551). (Japanese Unexamined Patent Publication (Kokai) No. 3-2)
Japanese Patent Application Laid-Open No. 30584/1990 describes a light emitting layer having a two-layer structure.
Japanese Patent Application Laid-Open No. 220390 and Japanese Patent Application Laid-Open No. 216790/1990 The light-emitting layer is divided into a plurality of layers and made of materials having different emission wavelengths (Japanese Patent Application Laid-Open No. 4-51491). Blue light emitter (fluorescence peak 380 to 480 nm) And a green light-emitting material (480-580 nm) laminated thereon and further containing a red phosphor (JP-A-6-207).
No. 170) A structure in which a blue light-emitting layer contains a blue fluorescent dye, a green light-emitting layer has a region containing a red fluorescent dye, and further contains a green phosphor (JP-A-7-142169) The above configuration is preferably used.

As the red phosphor, it is preferable to use the rhodamine dye of the present invention, but other substances can also be used in combination. Examples of red phosphors other than the rhodamine dye of the present invention are shown below.

[0057]

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As a method for forming the light emitting layer using the above-mentioned materials, a known method such as a vapor deposition method, a spin coating method, and an LB method can be applied. The light emitting layer is particularly preferably a molecular deposition film. This molecular deposition film is a thin film formed by deposition from a material compound in a gaseous state, or a film formed by solidification from a material compound in a solution state or a liquid phase state. And the thin film (accumulated molecular film) formed by the LB method can be classified according to the difference in the aggregation structure and the higher-order structure and the functional difference caused by the difference.

Further, as disclosed in JP-A-57-51781, after a binder such as a resin and a material compound are dissolved in a solvent to form a solution, the solution is formed into a thin film by a spin coating method or the like. By doing so, the light emitting layer can be formed. The thickness of the light emitting layer formed in this way is not particularly limited and can be appropriately selected depending on the situation, but is preferably in the range of 5 nm to 5 μm. This light-emitting layer may be composed of one or more of the above-mentioned materials, or may be a laminate of light-emitting layers made of a compound different from the light-emitting layer.

[Hole Injection Layer] Next, the hole injection layer
Is not necessary for the device used in the present invention,
It is preferable to use it for improving the optical performance.
This hole injection layer facilitates and facilitates hole injection into the light emitting layer.
Layer with high hole mobility and ionized energy
Energy is usually as small as 5.5 eV or less. Such a hole injection
As an ingress layer, holes are transported to the light-emitting layer with lower electric field strength
Is preferable, and the hole mobility is, for example, 1
0^Four-10⁶When an electric field of V / cm is applied, at least 10
^-6cm ^Two/ V · sec.

The hole injecting material is not particularly limited as long as it has the above-mentioned preferable properties, and it is conventionally used as a hole transporting material in a photoconductive material, Any known materials used for the hole injection layer of the device can be selected and used. Specific examples include, for example, a triazole derivative (see U.S. Pat. No. 3,112,197), an oxadiazole derivative (see U.S. Pat. No. 3,189,447), and an imidazole derivative (JP-B-37-16).
No. 096, etc.) and polyarylalkane derivatives (U.S. Pat. Nos. 3,615,402 and 3,82).
Nos. 0,989, 3,542,544, JP-B-45-555, JP-B-51-10983, JP-A-51-93224, and 55-171.
Nos. 05, 56-4148, 55-108
Nos. 667 and 55-15653 and 56-
No. 36656), pyrazoline derivatives and pyrazolone derivatives (U.S. Pat. Nos. 3,180,729 and 4,278,746; JP-A-55-8).
Nos. 8064, 55-88065, 49-
Nos. 105537, 55-51086 and 5
Nos. 6-80051, 56-88141, 57-54545, 54-112637 and 55-74546, and phenylenediamine derivatives (US Pat. No. 3,615,404). Specification, JP-B-51-10105, 46-3712
JP-A-47-25336, JP-A-54-53
No. 435, No. 54-110536, No. 54-
No. 119925), arylamine derivatives (U.S. Pat. Nos. 3,567,450 and 3,1).
Nos. 80,703, 3,240,597, 3,658,520 and 4,23
2,103, 4,175,961, 4,012,376, JP-B-49-3
5702, 39-27577 and JP-A-5
JP-A-5-144250, JP-A-56-119132, JP-A-56-22437, West German Patent No. 1,11
0,518), amino-substituted chalcone derivatives (see US Pat. No. 3,526,501),
Oxazole derivatives (as disclosed in U.S. Pat. No. 3,257,203), styryl anthracene derivatives (see JP-A-56-46234, etc.), and fluorenone derivatives (see JP-A-54-110837, etc.) ),
Hydrazone derivatives (US Pat. No. 3,717,462, JP-A-54-59143, and JP-A-55-520)
Nos. 63, 55-52064 and 55-46.
760, 55-85495, 57-1
1350, 57-148749, JP-A-2-311591, etc.), stilbene derivatives (JP-A-61-210363, 61-228)
No. 451, No. 61-14642, No. 61-7
Nos. 2255, 62-47646 and 62-
36674, 62-10652, 62
-30255, 60-93455, 6
JP-A-0-94462, JP-A-60-174747,
No. 60-175052), silazane derivatives (U.S. Pat. No. 4,950,950), polysilanes (JP-A-2-204996), and aniline-based copolymers (JP-A-2-282263). Gazette),
Conductive polymer oligomers (especially thiophene oligomers) disclosed in Japanese Patent Application Laid-Open No. 211399 can be used.

As the material for the hole injection layer, the above-mentioned materials can be used.
No. 3,295,965, etc.), aromatic tertiary amine compounds and styrylamine compounds (U.S. Pat. No. 4,127,412, JP-A-53-2703).
No. 3, No. 54-58445, No. 54-149
Nos. 634, 54-64299, 55-7
9450, 55-144250, 56
JP-119132, JP-A-61-295558,
JP-A-61-98353, JP-A-63-295695, etc.), and it is particularly preferable to use an aromatic tertiary amine compound.

Further, it has two condensed aromatic rings described in US Pat. No. 5,061,569 in the molecule.
For example, 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl (hereinafter abbreviated as NPD),
In addition, 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) -N-phenyl) in which three triphenylamine units described in JP-A-4-308688 are connected in a star-burst configuration. Amino) triphenylamine (hereinafter abbreviated as MTDATA) and the like.

Further, in addition to the above-mentioned aromatic dimethylidin compounds shown as materials for the light emitting layer, p-type Si, p-type
An inorganic compound such as SiC can also be used as a material for the hole injection layer. The hole injection layer can be formed by thinning the above-mentioned compound by a known method such as a vacuum evaporation method, a spin coating method, a casting method, and an LB method. The thickness of the hole injection layer is not particularly limited, but is usually 5 nm to 5 μm. This hole injection layer is
It may be composed of one or more of the above-mentioned materials, or may be a layer obtained by laminating a hole injection layer made of a compound different from the hole injection layer.

The organic semiconductor layer is a layer for promoting and facilitating hole injection or electron injection into the light emitting layer.
Those having a conductivity of ^-10 S / cm or more are suitable.
Examples of such a material for the organic semiconductor layer include conductive oligomers such as thiophene-containing oligomers and arylamine-containing oligomers disclosed in JP-A-8-193191.
Conductive dendrimers, such as arylamine-containing dendrimers, can be used.

[Electron Injection Layer] The electron injection layer is not always necessary for the device used in the present invention, but is preferably used for improving the light emitting performance. This electron injection layer is a layer that facilitates and facilitates the injection of electrons into the light emitting layer, has a high electron mobility, and has a high affinity level of usually 3 eV. As such an electron transfer compound used for the electron injecting layer, a material that transports electrons to the light emitting layer with lower electric field strength is preferable, and further, the mobility of electrons is, for example, an electric field of 10 ⁴ to 10 ⁶ V / cm. At the time of application, it is preferably at least 10 ⁻⁶ cm ² / V · sec. Such an electron transfer compound is not particularly limited as long as it has the above-mentioned preferable properties, and a compound conventionally used as a charge transport material for electrons in a photoconductive material, an electron transfer material of an organic EL device, and the like. Any one of known ones used for the injection layer can be selected and used.

As a specific material used for the electron injection layer, a metal complex of 8-hydroxyquinoline or a derivative thereof is preferable. In addition, when these materials are used, adhesion to the cathode is particularly good, and therefore, the electron mobility is large. In addition, such a layer made of a material having particularly good adhesion to the cathode among the electron injection layers is referred to as an adhesion improving layer. 8-
Specific examples of the metal complex of hydroxyquinoline or a derivative thereof include a metal chelate oxinoid compound including a chelate of oxine (generally, 8-quinolinol or 8-hydroxyquinoline).

More specifically, Alq described in the section of the light emitting material can be used as the electron injection layer. Other examples of the electron transfer compound include oxadiazole derivatives represented by the following general formula.

[0069]

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(Wherein Ar ¹ , Ar ² , Ar ³ , Ar ⁵ ,
Ar ⁶ and Ar ⁹ each represent a substituted or unsubstituted aryl group, which may be the same as or different from each other. Ar ⁴ , Ar ⁷ and Ar ^{8 each} represent a substituted or unsubstituted arylene group, which may be the same or different. Here, the aryl group is a phenyl group, a biphenyl group,
Examples include an anthranyl group, a perylenyl group, and a pyrenyl group. Examples of the arylene group include a phenylene group, a naphthylene group, a biphenylene group, an anthranylene group, a perylenylene group, a pyrenylene group, and the like. Examples of the substituent include an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and a cyano group. This electron transfer compound is preferably a thin film-forming compound.

The following are specific examples of the electron transfer compound.

[0072]

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The electron injection layer can be formed by thinning the above-mentioned compound by a known method such as a vacuum evaporation method, a spin coating method, a casting method, and an LB method. The thickness of the electron injection layer is not particularly limited,
Usually, it is 5 nm to 5 μm. The electron injection layer may be composed of one layer or one or more of the above-mentioned materials, or may be an electron injection layer made of a compound different from the electron injection layer. .

[Cathode] As the cathode, a metal, an alloy, an electrically conductive compound having a small work function (4 eV or less), and a mixture thereof as an electrode material are used. Specific examples of such an electrode material include sodium, sodium-potassium alloy, magnesium, lithium, magnesium-silver alloy, aluminum / aluminum oxide, aluminum-lithium alloy, indium, and rare earth metals.

The cathode can be manufactured by forming a thin film from these electrode substances by a method such as vapor deposition or sputtering. Here, when the light emitted from the light emitting layer is taken out from the cathode, the transmittance for the emitted light of the cathode is 1
Preferably, it is larger than 0%. Further, the sheet resistance as the cathode is preferably several hundreds Ω / □ or less, and the film thickness is usually 10 nm to 1 μm, more preferably 50 to 200 nm.

[Example of Manufacturing Organic EL Device] By forming an anode, a light emitting layer, and if necessary, a hole injection layer and / or an electron injection layer by the materials and methods exemplified above, and further forming a cathode. An organic EL device can be manufactured. Further, from the cathode to the anode, the organic E
An L element can also be manufactured.

Hereinafter, the anode / hole injection layer /
A production example of an organic EL device having a structure in which a light emitting layer / an electron injection layer / a cathode is provided in this order will be described. First, a thin film made of an anode material is formed on an appropriate translucent substrate by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 10 to 200 nm, to produce an anode. next,
A hole injection layer is provided on the anode. As described above, the hole injection layer can be formed by a vacuum deposition method, a spin coating method, a casting method, an LB method, or the like, but a uniform film is easily obtained and pinholes are not easily generated. From the viewpoint of the above, it is preferable to form by a vacuum evaporation method. When the hole injection layer is formed by a vacuum evaporation method, the deposition conditions vary depending on the compound used (material of the hole injection layer), the crystal structure of the target hole injection layer, the mobility of carriers (charges), and the like. However, generally, the vapor deposition source temperature is 50 to 450 ° C., the degree of vacuum is 10 ⁻⁷ to 10 ⁻³ torr, and the vapor deposition rate is 0.01 to 50 nm.
/ Sec, substrate temperature -50 to 300 ° C, film thickness 5 nm to 5 μm
It is preferable to select appropriately within the range. Next, formation of a light-emitting layer in which a light-emitting layer is provided on a hole injection layer is also performed by using a desired organic light-emitting material to reduce the thickness of the organic light-emitting material by a method such as vacuum evaporation, sputtering, spin coating, or casting. However, it is easy to obtain a uniform film,
In addition, it is preferable to form them by a vacuum evaporation method from the viewpoint that pinholes are hardly generated. When the light emitting layer is formed by a vacuum deposition method, the deposition conditions vary depending on the compound used, but can be generally selected from the same condition range as the hole injection layer.

Next, an electron injection layer is provided on the light emitting layer. Like the hole injection layer and the light emitting layer, it is preferable to form the film by a vacuum deposition method from the viewpoint of obtaining a uniform film. The deposition conditions can be selected from the same condition ranges as for the hole injection layer and the light emitting layer. The specific rhodamine-based dye represented by the general formula (I), which is a feature of the present invention, differs depending on which layer is contained. However, when a vacuum evaporation method is used, co-evaporation with another material may be used. it can. When the spin coating method is used, it can be contained by mixing with another material.

Finally, an organic EL device can be obtained by laminating a cathode. The cathode is made of a metal, and an evaporation method or sputtering can be used. However, in order to protect the underlying organic material layer from damage such as heat during film formation,
Vacuum evaporation is preferred. It is preferable that the organic EL element is manufactured by sequentially laminating under vacuum without contacting with the outside air from the formation of the anode to the formation of the cathode.

When a DC voltage is applied to the organic EL element, light emission can be observed by applying a voltage of 5 to 40 V with the anode having a positive polarity and the cathode having a negative polarity. No current flows, and no light emission occurs. Furthermore, when an AC voltage is applied, uniform light emission is observed only when the anode has a positive polarity and the cathode has a negative polarity. The waveform of the applied alternating current may be arbitrary.

[0081]

Next, embodiments of the present invention will be described. However, the present invention is not limited to the following examples. Example 1 (Production of Color Conversion Film and Evaluation of Color Conversion Film) First, a method for producing a color conversion film will be described.

Coumarin 6, Rh as a pigment in a sample bottle
10 mg of each of 6G and Rh-01 were added, and 1 g of a benzoguanamine resin (manufactured by Schinloich) was added as a binder resin. This was dissolved with 1 g of ethyl cellosolve.

[0083]

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[0084]

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A few drops of this solution were placed on a commercially available slide glass, and the slide glass was rotated at a rotation speed of 500 dps for 20 seconds using a spin coater to form a film. This was dried on a hot plate at 80 ° C. for 15 minutes to produce a color conversion film. This color conversion film is referred to as RCCM1. The thickness of the produced color conversion film is measured by a surface roughness meter (DEKTAK303).
0).

Next, a method for evaluating the color conversion film will be described. On the glass substrate on the side where the light emission of the organic EL element is taken out,
A few drops of an inert liquid Fluorinert 70C (manufactured by 3M) were applied, and RCCM1 was stuck on the substrate of the organic EL element. The organic EL element was driven, and the light output through the RCCM1 was measured for emission luminance and CIE chromaticity coordinates using a colorimeter (CS100 manufactured by Minolta). Table 1 shows the results.

The light emission luminance and CIE chromaticity coordinates of the organic EL element serving as a light source are 200 cd / m ² , (0.16
0.24). [Example 2] (Production of color conversion film and evaluation of color conversion film) Except that Rh-02 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM2. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 3 (Production of Color Conversion Film and Evaluation of Color Conversion Film) Except that Rh-03 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM3. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results. [Example 4] (Production of color conversion film and evaluation of color conversion film) Except that Rh-04 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is called RCCM4. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 5 (Production of Color Conversion Film and Evaluation of Color Conversion Film) Except that Rh-05 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM5. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results. [Example 6] (Production of color conversion film and evaluation of color conversion film) Except that Rh-06 was used in place of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM6. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 7 (Production of Color Conversion Film and Evaluation of Color Conversion Film) Except that Rh-07 was used in place of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM7. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results. [Example 8] (Production of color conversion film and evaluation of color conversion film) Except that Rh-08 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM8. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 9 (Preparation of Color Conversion Film and Evaluation of Color Conversion Film) Except that Rh-09 was used in place of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM9. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results. [Example 10] (Production of color conversion film and evaluation of color conversion film) Except that Rh-10 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM10. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 11 (Preparation of Color Conversion Film and Evaluation of Color Conversion Film) Except that Rh-11 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM11. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results. [Example 12] (Production of color conversion film and evaluation of color conversion film) Except that Rh-12 was used in place of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM12. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 13 (Preparation of Color Conversion Film and Evaluation of Color Conversion Film) Except that Rh-21 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM13. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results. [Example 14] (Production of color conversion film and evaluation of color conversion film) Except that Rh-22 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM14. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 15 (Production of Color Conversion Film and Evaluation of Color Conversion Film) Except that Rh-24 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM15. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results. [Example 16] (Production of color conversion film and evaluation of color conversion film) Except that Rh-30 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM16. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 17 (Preparation of Color Conversion Film and Evaluation of Color Conversion Film) Except that Rh-31 was used in place of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM17. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results. [Example 18] (Production of color conversion film and evaluation of color conversion film) Except that Rh-32 was used instead of Rh-01,
A color conversion film was produced in the same manner as in Example 1. This color conversion film is referred to as RCCM18. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results.

[Comparative Example 1] (Preparation of color conversion film and evaluation of color conversion film) The same as Example 1 except that Rh-610 represented by the following formula was used instead of Rh-01. To produce a color conversion film. This color conversion film is referred to as RCCM610. Then, the color conversion film was evaluated in the same manner as in Example 1. Table 1 shows the results.

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From the above results, according to the color conversion film of the present invention, the color conversion film RCCM using the conventional rhodamine-based dye was used.
610 (see [Comparative Example 1]), it is found that the color conversion efficiency is significantly higher. This is because the introduction of a sterically hindered substituent into the molecule suppresses the molecular association,
As a result, it is considered that the concentration quenching of the rhodamine dye was reduced.

Thus, it was possible to greatly contribute to the improvement of red conversion efficiency, which was a problem of the conventional color conversion method.

[0100]

[Table 1]

Example 19 (Production and Evaluation of Organic EL Element) First, a transparent anode of indium tin oxide was coated on glass and provided. The indium tin oxide was about 750 Å thick and the glass was (25 mm × 75 mm × 1.1 mm) in size. This glass plate is vacuum-evaporated (Nihon Vacuum Technology Co., Ltd.)
And then reduced the pressure to about 10 ^-6 torr.
TDATA was deposited to a thickness of 600 Å. The deposition rate at this time was 2 Å / sec.

Next, NPD was deposited to a thickness of 200 angstroms. The deposition rate at this time was 2 Å / sec. Next, Alq and Rh-06 were co-evaporated to form a light emitting layer having a thickness of 400 angstroms. At this time, the deposition rate of Alq was 50 angstroms / second, and the deposition rate of Rh-06 was 1 angstroms / second.

Further, only Alq was deposited at a deposition rate of 2 Å / sec. Finally, a cathode was formed with a thickness of 2000 Å by co-evaporating magnesium and silver. At this time, the deposition rate of magnesium was 20 angstroms / second, and the deposition rate of silver was 1 angstroms / second. When a voltage of 8 V was applied to the obtained device, the current density was 2.8 mA /
cm ² , and emitted red light with a luminance of 88 cd / m ² . The luminous efficiency at this time was 1.2 lm / W.

[0104]

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[0105]

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[0106]

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Comparative Example 2 (Production and Evaluation of Organic EL Element) An organic EL element was produced in the same manner as in Example 19 except that Rh610 was used instead of Rh-06. When a voltage of 8 V was applied to the obtained device,
The current density was 2.9 mA / cm ² and the luminance was 34 cd / cm ^2.
It emitted red light of m ² . The luminous efficiency at this time is 0.46
lm / W.

From the above results, it was found that the rhodamine-based dye of the present invention is extremely effective as a luminescent material for an organic EL device because concentration quenching is significantly suppressed by a sterically hindered substituent contained in the molecule. Was.

Claims (8)

[Claims] 1. A rhodamine-based dye having at least one sterically hindered group in a molecule that inhibits formation of an aggregate. 2. The rhodamine-based dye according to claim 1, wherein the sterically hindered group is any of the following substituents. A long-chain substituent having 6 or more main chain atoms, a substituent having at least one quaternary carbon atom, having at least one unsaturated bond in the main chain, and having at least one carbon atom having the unsaturated bond. A substituent bound to two substituents having 6 or more nuclear atoms, a substituent having at least 3 or more halogen atoms 3. A dye represented by the following general formula (I). Embedded image [Wherein, at least one of R ^{1 to} R ⁶ is a sterically hindered group that inhibits formation of an aggregate, X is O or S, and A
Represents a counter ion. ] 4. In the formula (I), R ^{1 to} R ^{6 which} are not sterically hindered groups each independently represent hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, 6 ~
The dye according to claim 3, which is 24 aryl groups, hydroxyl groups, amino groups, halogen groups, nitro groups, cyano groups, amide groups, carboxyl groups, ester groups, or sulfone groups. 5. A dye represented by the following general formula (II). Embedded image [In the formula, at least one of R ^{1 to} R ⁶ is a substituent of any of the following to, X is O or S, and A represents a counter ion. A long-chain substituent having 6 or more main chain atoms, a substituent having at least one quaternary carbon atom, having at least one unsaturated bond in the main chain, and having at least one carbon atom having the unsaturated bond. A substituent bonded to two substituents having 6 or more nuclear atoms. A substituent having at least 3 or more halogen atoms. ] 6. In the general formula (II), R ^{1 to} R ⁶ that are not any of the substituents are each independently hydrogen,
An alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 to 24 core carbon atoms, a hydroxyl group,
The dye according to claim 5, which is an amino group, a halogen group, a nitro group, a cyano group, an amide group, a carboxyl group, an ester group, or a sulfone group. 7. A color conversion film obtained by dispersing the dye according to claim 1 in a resin. 8. An organic electroluminescent device comprising an organic compound layer having at least an organic light emitting layer sandwiched between a pair of electrodes, wherein the organic compound layer contains the dye according to any one of claims 1 to 6.