JP2000044824A - Color conversion film and organic electroluminescence device - Google Patents

Abstract

(57) Abstract: A color conversion film capable of converting blue light into red light with high conversion efficiency by combining with a light emitting source such as an organic EL element, and an organic EL element capable of emitting red light with high efficiency To provide. SOLUTION: A color conversion film made of a resin in which a rhodamine dye having at least one cycloalkyl group and / or heterocyclo ring as a steric hindrance group is dispersed, and at least one of the organic compound layers contains the above rhodamine dye. An organic EL device comprising:

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color conversion film and an organic electroluminescence element (hereinafter, electroluminescence is abbreviated as "EL"). More specifically, the present invention relates to a color conversion film capable of converting blue light into red light with high conversion efficiency by combining with a light emitting source such as an organic EL element, and an organic EL element capable of emitting red light with high efficiency.

[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 be driven at a low voltage of several volts. Therefore, research is currently being actively conducted. The biggest problem when using an organic EL element as a display is the development of a method for full-color display. In order to realize this full-color display, light emission of three primary colors of blue, green, and red must be finely arranged in a two-dimensional direction. Currently, the following methods have been proposed. Three-color array method Color filter method Color conversion film method

The above-mentioned method is a method of forming one color pixel by three pixels using light emission sources of three primary colors.
Since organic EL elements are difficult to perform wet patterning,
There is a disadvantage that it is difficult to produce a high-definition display. The above method uses a white light source and performs color conversion with a color filter 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. Under such circumstances, the present inventors have been studying full-color organic EL devices by the color conversion film method, but the conversion efficiency from blue to red is low and can be sufficiently satisfied. It was not something. On the other hand, it is actually difficult for an organic EL element to emit red light with high efficiency. Therefore, it has been desired to develop an organic EL element capable of emitting red light with high efficiency.

[0004]

SUMMARY OF THE INVENTION The present invention provides a color conversion film capable of converting blue light into red light with high conversion efficiency by combining with a light emitting source such as an organic EL element under such circumstances. It is an object of the present invention to provide an organic EL device capable of emitting red light with high efficiency.

[0005]

The present inventors have conducted intensive studies to achieve the above object. As a result, the rhodamine-based dye having a specific sterically hindered group is inhibited from associating with the dye and has a concentration quenching. Focusing on the fact that the color conversion film made of a resin in which such rhodamine-based dye is dispersed can convert blue light into red light with high conversion efficiency,
It has been found that an organic EL device containing the above rhodamine-based dye in at least one of the organic compound layers can emit red light with high efficiency. The present invention has been completed based on such findings. That is, the present invention provides a color conversion film made of a resin in which a rhodamine-based dye having at least one cycloalkyl group and / or heterocyclo ring as a steric hindrance group is dispersed. Further, the present invention provides an organic EL device comprising a pair of electrodes and an organic compound layer having at least an organic light emitting layer sandwiched therebetween.
In the L element, an organic EL element is provided, wherein at least one of the organic compound layers contains a rhodamine-based dye having at least one cycloalkyl group and / or heterocyclo ring as a steric hindrance group. .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The rhodamine dye used in the color conversion film and the organic EL device of the present invention needs to have at least one cycloalkyl group and / or heterocyclo ring as a steric hindrance group. The rhodamine-based dye having such a sterically hindered group effectively suppresses the association of the dye and consequently suppresses the concentration quenching of the dye. Therefore, when used in a color conversion film or an organic EL device, the present invention provides Aim is achieved. Among the rhodamine dyes, those having at least one cycloalkyl group include, for example, those represented by the general formula (I)

[0007]

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Compounds represented by the following formulas can be preferably mentioned. In this general formula (I), at least one of R ^{1 to} R ⁴ is an unsubstituted or substituted cycloalkyl group having 3 to 12 ring carbon atoms, and the rest is a hydrogen atom or an alkyl group having 1 to 32 carbon atoms. Or an unsubstituted or substituted aryl group having 6 to 24 core carbon atoms. Here, examples of the cycloalkyl group having 3 to 12 ring carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclododecyl group, an adamantyl group, and the like. The substituent which may be introduced into the cycloalkyl group will be described later. In addition, carbon number 1-3
The alkyl group 2 may be linear or branched, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group,
sec-butyl group, tert-butyl group, pentyl group,
Examples include hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, and behenyl. Nuclear carbon number 6 ~ 2
Examples of the aryl group 4 include a phenyl group, a biphenyl group, a naphthyl group, an anthranyl group, a terphenyl group, a pyrenyl group and the like. The substituents that may be introduced into the aryl group will be described later. R ⁵ is a hydrogen atom, an alkyl group having 1 to 32 carbon atoms, an unsubstituted or substituted cycloalkyl group having 3 to 12 ring carbon atoms, an unsubstituted or substituted nuclear carbon atom having 6 carbon atoms.
To 24 aryl groups or aralkyl groups. here,
The alkyl group having 1 to 32 carbon atoms, the cycloalkyl group having 3 to 12 ring carbon atoms, and the aryl group having 6 to 24 core carbon atoms are as described above. Examples of the aralkyl group having 6 to 24 core carbon atoms include a benzyl group, a phenethyl group, a phenylpropyl group, a naphthylmethyl group and a phenylbenzyl group.

[0009] A substituent may be introduced into the benzene ring to which -COOR ⁵ is bonded. The substituent and the substituent which may be introduced into the cycloalkyl group, the aryl group, and the aralkyl group are not particularly limited, and may be, for example, an alkyl group or an alkoxy group having 1 to 32 carbon atoms, or a ring having 3 to 3 carbon atoms. 12 cycloalkyl groups or cycloalkoxy groups, aryl groups or aryloxy groups having 6 to 24 nuclear carbon atoms, hydroxyl groups, amino groups, alkylamino groups, halogen groups (F, Cl, Br, I), nitro groups, cyano groups Group, alkylamide group, arylamide group,
Examples include a carboxyl group, an aryl ester group, an alkyl ester group, and a sulfone group. A ⁻ represents a counter ion, for example, a halogen ion, a boron-containing complex ion, a metal complex ion, a peroxide ion and the like. Examples ^{F -, Cl -, Br -} , I
_{^{-, BF 4 -, BPh 4}} -, B (Ph-Cl) 4 -, B
(Ph-F) ₄ ⁻ , ZnCl ₄ ²⁻ , ClO ₄ ⁻ ,

[0010]

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And the like. Ph represents a phenyl group. On the other hand, examples of the rhodamine-based dye having at least one heterocyclo ring include compounds represented by the following general formula (II):

[0012]

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Compounds represented by the following formula (1) are preferred. In the general formula (II), R ^{6 to} R ⁹ represent R
^At least one pair of ⁶ and R ⁷ and R ⁸ and R ⁹ are bonded to each other via a saturated or unsaturated linking group having 3 to 9 carbon atoms to form a heterocyclo ring having N as a hetero atom. And the remainder is a hydrogen atom, an alkyl group having 1 to 32 carbon atoms, an unsubstituted or substituted ring carbon atom having 3 to 12 carbon atoms.
Or an unsubstituted or substituted aryl group having 6 to 24 nuclear carbon atoms. As a saturated or unsaturated linking group contributing to the formation of a cycloheterocycle, for example,

[0014]

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The groups represented by the following are preferred. Further, the remaining groups among R ^{6 to} R ⁹ , that is, C 1 to C ⁹
For an alkyl group of 32, an unsubstituted or substituted cycloalkyl group having 3 to 12 ring carbon atoms, and an unsubstituted or substituted aryl group having 6 to 24 ring carbon atoms,
As described in the general formula (I). R ⁵
And A ^- are the same as those in formula (I), and a substituent may be introduced into the benzene ring to which -COOR ⁵ is bonded. Further, as each substituent, the same as those exemplified as the substituent in the general formula (I) can be exemplified. The rhodamine dye used in the present invention is characterized by having at least one cycloalkyl group and / or heterocyclo ring as a steric hindrance group. It is generally known that when a dye is dispersed at a high concentration in a solution or a resin, an aggregate is formed between the dye molecules and the fluorescence is significantly reduced. This phenomenon is called concentration quenching. The present invention introduces a cycloalkyl group or a heterocyclo ring into a rhodamine dye molecule, thereby causing steric hindrance.
This is to suppress the above-mentioned undesirable phenomenon. Specific examples of the rhodamine dyes represented by the general formulas (I) and (II) are shown below. Me: methyl group, Et: ethyl group, t-Bu: tert-butyl group, Ph: phenyl group.

[0016]

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[0017]

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[0018]

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[0019]

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[0020]

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The color conversion film of the present invention comprises a resin in which the above-mentioned rhodamine dye according to the present invention, for example, a compound represented by the general formula (I) or (II) is dispersed. Other dyes may be used in combination and dispersed.
Examples of the dye other than the rhodamine dye according to the present invention include a coumarin dye, a perylene dye, a phthalocyanine dye, a stilbene dye, a cyanine dye, a polyphenylene dye, and other rhodamine dyes. The total content of the dye in the resin is not particularly limited, but it is preferable that the dye be contained in the range of 0.01 to 10 parts by weight with respect to 100 parts by weight of the resin. The resin in which these dyes are dispersed is transparent (having a light transmittance of 50% in the visible light region).
As described above, a resin having a small coefficient of thermal expansion is preferable, and a photosensitive resin to which a photolithography method can be applied is preferable in order to pattern-process the color conversion film and dispose it two-dimensionally. 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 resin, oligomer or polymer of polyamide resin, polymethyl methacrylate, polyacrylate, polycarbonate, polyvinyl alcohol,
Polyvinyl pyrrolidone, hydroxyethyl cellulose,
A transparent resin such as carboxymethyl cellulose can be used. Other examples include aromatic sulfonamide resins, urea resins, and benzoguanamine resins.

Among these resins, urea resins, benzoguanamine resins and melamine resins are preferred. In addition, the said resin may be used independently and may be used in combination of 2 or more type. The color conversion film of the present invention is formed by dispersing the above-described dye in a resin and forming the same on a light-transmitting substrate, but the film forming method is not particularly limited. Specifically, a casting method, a spin coating method, a coating method, a vapor deposition method, an electrolytic method, a printing method and the like can be mentioned, but a spin coating method is generally preferred. The film thickness of the color conversion film formed by the above method needs to be appropriately selected from the film thickness required to convert 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 may be a smooth substrate having a light transmittance of 50% or more in a visible light region of 400 to 700 nm of 50% or more. preferable. Specific examples include a glass substrate and a polymer plate. Glass plates include soda-lime glass, barium / strontium-containing glass, lead glass,
Examples include aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic resin, polyethylene terephthalate, polyether sulfide, and polysulfone.

The color conversion film of the present invention is preferably used for wavelength conversion of light from the light emitting source by being combined with a light emitting source. The light source is not particularly limited, and may be, for example, an organic EL device or an LED (light emitting device). Diode), cold-cathode tube,
Examples thereof include an inorganic EL element, a fluorescent lamp, an incandescent lamp, and sunlight, and among these, an organic EL element is preferable. That is, it is advantageous to use the color conversion film of the present invention when a display using an organic EL element is made full-color.
When the color of the light emitting source is wavelength-converted by the color conversion film of the present invention, a color filter may be additionally provided depending on a desired wavelength to adjust 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, triphenylmethane basic dyes, indanthrone pigments, indophenol pigments, Examples of the pigment include a single pigment such as a cyanine pigment and a dioxazine pigment, and a pigment only composed of a mixture of at least two or more pigments, or a solid pigment in which the pigment is dissolved or dispersed in a binder resin. The configuration using the color conversion film of the present invention includes the following examples. (1) Light source / color conversion film (2) Light source / light transmission substrate / color conversion film (3) Light source / color conversion film / light transmission substrate (4) Light source / light transmission substrate / color conversion film / light transmission (5) Light source / color conversion film / color filter (6) Light source / light-transmitting substrate / color conversion film / color filter (7) Light source / color conversion film / light-transmitting substrate / color filter (8) light source / Transparent substrate / color conversion film / transparent substrate / color filter (9) Light source / transparent substrate / color conversion film / color filter / transparent substrate (10) Light source / color conversion film / color filter / transparent Optical substrate

In the case of manufacturing the above-mentioned structure, the respective components may be sequentially laminated or bonded. Also,
In the case of manufacturing, there is no particular limitation on the order, and in the above configuration, the order may be left to right or right to left. Next, the organic EL device of the present invention will be described. The organic EL device of the present invention is a device in which the above-mentioned rhodamine dye according to the present invention is contained in at least one layer of an organic compound layer having at least an organic light emitting layer sandwiched between a pair of electrodes. Organic EL containing the dye
When the device is manufactured, there is no particular limitation on the configuration, material, and the like, and the device may be manufactured in accordance with the configuration, material, and the like when an organic EL device is manufactured.

The configuration of the organic EL device of the present invention includes, for example, 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 emission 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 / electron injection layer / cathode, etc. Among them, a normal structure is preferably used. Rhodamine dyes according to the present invention,
It is necessary that at least one of the organic compound layers in these structures be contained. The content is 0.0 based on the total amount of organic compounds in the layer containing the rhodamine dye.
1 to 50 mol% is preferable, and 0.01 to 10 mol% is particularly preferable.

Translucent substrate: The organic EL device of the present invention is manufactured on a translucent substrate. This translucent substrate is made of the organic E
It is preferable that the substrate which supports the L element has a transmittance of light of at least 50% in a visible light region of 400 to 700 mm and a smooth surface. Specific examples include a glass plate and a polymer plate. As the glass plate, in particular, soda-lime glass, glass containing barium and strontium,
Lead glass, aluminosilicate glass, borosilicate glass,
Barium borosilicate glass, quartz and the like can be mentioned. Examples of the polymer plate include polycarbonate, acrylic resin, 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, CuI, ITO (indium tin oxide), S
Conductive materials such as nO ₂ and ZnO can be used. And
The anode can be manufactured by forming a thin film from these electrode substances by a method such as an evaporation method or a sputtering method. When the light emission of the light emitting layer is extracted from the anode formed in this way, the transmittance of the anode with respect to the light emission is set to 10%.
%. Similarly, the sheet resistance of the anode is preferably several hundred Ω / □ or less. In order to ensure the above-mentioned performance, the thickness of the anode is selected in the range of usually 10 nm to 1 μm, preferably 10 to 200 nm, although it depends on the material of the anode.

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 Emitting function; It provides a field for recombination of electrons and holes, and has a function of 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 transportability represented by the mobility of holes and electrons may be large or small. It is preferable to transfer 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.
First, when obtaining violet light emission from the ultraviolet region, a compound represented by the following general formula may be mentioned.

[0030]

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In this general formula, X represents the following groups.

[0032]

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Here, m is an integer of 2 to 5. Also Y
Represents a phenyl group or a naphthyl group. The groups represented by X and Y, ie, phenylene, phenyl, and naphthyl are alkyl, alkoxy, hydroxyl, sulfonyl, carbonyl, amino, dimethylamino, diphenylamino groups having 1 to 4 carbon atoms. May be substituted singly or plurally. Further, they may combine 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, they are the following compounds. In particular, p-quarter phenyl derivatives and p-quink phenyl derivatives are preferred.

[0034]

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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. Examples of the chelated oxinoid compounds include, for example,
The one disclosed in JP-A-3-295695 can be used. Typical examples thereof include 8-hydroxyquinoline-based metal complexes such as tris (8-quinolinol) aluminum (hereinafter abbreviated as Alq) and dilithium epinetridione. Examples of the styrylbenzene compound include, for example, European Patent No. 0319.
881 and EP 0 375 582 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, particularly, as a material for the light emitting layer, an aromatic dimethylidin-based compound (European Patent No. 0388768 or
It is preferable to use those disclosed in JP-A-231970). As a specific example, 4,4′-bis (2,2-di-
t-butylphenylvinyl) biphenyl, (hereinafter DT)
BPBBi), 4,4'-bis (2,2-diphenylvinyl) biphenyl (hereinafter abbreviated as DPVBi), and the like, and derivatives thereof.

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 highly efficient mixed light emission of blue and green 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, as a host, a luminescent material having a distyrylarylene skeleton, particularly preferably DP
As VBi and the dopant, diphenylaminovinylarylene, particularly preferably, for example, N, N-diphenylaminovinylbenzene (DPAVB) can be mentioned. The light-emitting layer that emits white light is not particularly limited, and examples thereof include the following. A white light-emitting element is described as an example of an element using tunnel injection similarly to an element that specifies the energy level of each layer of the organic EL laminated structure and emits light using tunnel injection (European Patent No. 0390551). (Japanese Unexamined Patent Application Publication 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. Further, as the red phosphor, it is preferable to use the rhodamine-based dye according to the present invention, but other substances can also be used in combination. Examples of red phosphors other than the rhodamine dye according to the present invention are shown below.

[0039]

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As a method for forming a light emitting layer using the above-mentioned materials, a known method such as an evaporation 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. Also, a light emitting layer can be formed. The thickness of the light emitting layer formed in this manner is not particularly limited and can be appropriately selected depending on the situation, but is usually preferably in the range of 5 nm to 5 μm. The 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 necessarily required for the device of the present invention, but is preferably used for improving the light emitting performance. This hole injection layer is a layer that facilitates and facilitates the injection of holes into the light emitting layer, has a high hole mobility, and a small ionization energy of usually 5.5 eV or less. As such a hole injecting layer, a material that transports holes to the light emitting layer with a lower electric field strength is preferable, and the mobility of holes is, for example, 10 ⁴ to 10
^When an electric field of ⁶ V / cm is applied, at least 10 ⁻⁶ cm ² /
V · sec is preferred. Such a hole injecting material is not particularly limited as long as it has the above-mentioned preferable properties, and a material commonly used as a charge transporting material for holes in a photoconductive material and a positive electrode material of an EL element have been conventionally used. Any one of known materials used for the hole injection layer can be selected and used.

As specific examples, for example, triazole derivatives (see US Pat. No. 3,112,197 etc.), oxadiazole derivatives (see US Pat. No. 3,189,447 etc.), imidazole derivatives (Japanese Patent Publication No. Sho 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
JP-A-6-80051, JP-A-56-88141, JP-A-57-45545, JP-A-54-112637, JP-A-55-74546, etc.), 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 (those 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, those described above 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. In addition, for example, 4,4′-bis (N- (1-naphthyl) -N having two condensed aromatic rings described in US Pat. No. 5,061,569 in a molecule.
-Phenylamino) biphenyl (hereinafter abbreviated as NPD) and 4,4 ', 4 "-tris in which three triphenylamine units described in JP-A-4-308688 are connected in a star-burst form. (N- (3-
Methylphenyl) -N-phenylamino) triphenylamine (hereinafter abbreviated as MTDATA) and the like.

Further, in addition to the above-mentioned aromatic dimethylidin compound shown as a material 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 layers 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 facilitates and facilitates the injection of holes or electrons into the light-emitting layer, and preferably has a conductivity of 10 ⁻¹⁰ S / cm or more. As a material for such an organic semiconductor layer, a conductive oligomer such as a thiophene-containing oligomer or an arylamine-containing oligomer disclosed in JP-A-8-193191, or a conductive dendrimer such as an arylamine-containing dendrimer is used. be able to.

Electron injection layer: The electron injection layer is a layer that assists the injection of electrons into the light-emitting layer, has a high electron mobility, and the adhesion improving layer is one of the electron injection layers, particularly the one that adheres to the cathode. Is a layer made of a good material. As a material used for the electron injection layer, a metal complex of 8-hydroxyquinoline or a derivative thereof is preferable. Specific examples of the metal complex of 8-hydroxyquinoline or a derivative thereof include a metal chelate oxinoid compound containing a chelate of oxine (generally, 8-quinolinol or 8-hydroxyquinoline). For example, A described in the section of the luminescent material
lq can be used as the electron injection layer. On the other hand, examples of the oxadiazole derivative include an electron transfer compound represented by the following general formula.

[0046]

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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. Specific examples of the electron transfer compound include the following.

[0048]

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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 formed of a compound different from the electron injection layer. .

Cathode: The cathode has a small work function (4
eV or less) A metal, an alloy, an electrically conductive compound, and a mixture thereof are used as an electrode material. 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 materials by a method such as evaporation or sputtering. Here, when light emission from the light emitting layer is taken out from the cathode, the transmittance for the light emission of the cathode is 10%.
%. Further, the sheet resistance as the cathode is preferably several hundred Ω / □ or less, and
It is preferably from 0 nm to 1 μm, more preferably from 50 to 200 nm.

Preparation Example of Organic EL Device: An anode, a light emitting layer, a hole injection layer, and / or an electron injection layer, if necessary, are formed by the above-described materials and methods, and a cathode is formed. An EL element can be manufactured. In addition, from the cathode to the anode, the organic EL is reversed in the order described above.
An element can also be manufactured. Hereinafter, an example of manufacturing an organic EL element having a structure in which an anode / a hole injection layer / a light emitting layer / an electron injection layer / a cathode is provided in this order on a light-transmitting substrate will be described. First, a thin film made of an anode material is formed to a thickness of 1 μm or less, preferably 1 μm, on a suitable translucent substrate by a method such as evaporation or sputtering.
The anode is formed so as to have a thickness in the range of 0 to 200 nm. 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 to be used (the material of the hole injection layer), the crystal structure and the recombination structure of the target hole injection layer, etc. Source temperature 50 to 450 ° C., degree of vacuum 10 ⁻⁷ to 10 ⁻³ torr, deposition rate 0.01 to 50
nm / sec, substrate temperature -50 to 300 ° C, film thickness 5 nm to 5
It is preferable to appropriately select within the range of μm.

Next, the formation of the light emitting layer in which the light emitting layer is provided on the hole injecting layer is also performed by a vacuum evaporation method using a desired organic light emitting material,
It can be formed by thinning the organic light-emitting material by a method such as sputtering, spin coating, or casting, but is formed by a vacuum evaporation method from the viewpoint that a uniform film is easily obtained and pinholes are hardly generated. Is preferred. 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 which is a feature of the present invention differs depending on which layer is contained,
When a vacuum evaporation method is used, co-evaporation with another material can be performed. When the spin coating method is used, it can be contained by mixing with another material.
Finally, a cathode is laminated to obtain an organic EL device. The cathode is made of a metal, and an evaporation method or sputtering can be used. However, in order to protect the underlying organic layer from damage such as heat during film formation, a vacuum deposition method is preferable. 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. In addition, organic EL
When a DC voltage is applied to the device, light emission can be observed when a voltage of 5 to 40 V is applied with the anode having a positive polarity and the cathode having a negative polarity. Does not occur at all. 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.

[0054]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Production Example 1 Production of Rh02 (Symmetric Type) 8- (N-cyclohexyl-N-methyl) aminophenol 1 part by weight, 2- [2-hydroxy-4- (N-cyclohexyl-N-methyl) aminobenzoyl] benzoic acid A mixture of 2 parts by weight and 8.5 parts by weight of 98% sulfuric acid was added at room temperature to 1 part.
After reacting for 7 hours, the reaction product was gradually poured into 70 parts by weight of ice water. After suction filtration of the precipitate, the cake was dissolved in 70 parts by weight of a dilute aqueous sodium hydroxide solution, adjusted to pH 4.5, filtered again and dried to obtain 2 parts by weight of a crude rhodamine as a dark solid (yield 90%). Was. This crude rhodamine was dissolved in 10 parts by weight of methanol, and 40% by weight of hydrochloric acid was added to the solution.
A methanol solution of 1 part by weight and 0.6 part by weight of sodium tetraphenylborate was added dropwise, stirred at room temperature for 2.5 hours, and subsequently mixed with 20 parts by weight of water. The precipitated boronate was filtered off and dried to obtain 1 part by weight (yield 78%) of dark red Rh02. Production Example 2 Production of Rh04 (Asymmetric) 1 part by weight of 3- (N-cyclohexyl-N-methyl) aminophenol, 1.4 parts by weight of 2- [2-hydroxy-4-pyrrolidinebenzoyl] benzoic acid and 98% sulfuric acid 6.5 parts by weight of the mixture was allowed to react at room temperature for 24 hours,
The mixture was gradually added to 4 parts by weight. After suction filtration of the precipitate,
Dissolve the cake in 44 parts by weight of dilute aqueous sodium hydroxide solution,
Adjusted to 6.7, filtered again and dried to give crude rhodamine as 1.7 parts by weight (80% yield) as a dark solid. To a solution of this crude rhodamine in 10 parts by weight of methanol, a methanol solution of 0.2 parts by weight of 40% by weight hydrochloric acid and 0.4 parts by weight of sodium tetraphenylborate was added dropwise and stirred at room temperature for 3 hours. And subsequently mixed with 20 parts by weight of water. The precipitated boronate is filtered off, dried and the dark red R
0.7 part by weight (yield 62%) of h04 was obtained.

Production Example 3 Production of Rh08 (ester type) 1 part by weight of crude rhodamine (Rh02 closed ring) was
-Dissolved in 6 parts by weight of hexanol and hydrogen chloride was bubbled through the solution at 80 ° C for 2 hours. After cooling, the solution was concentrated to dryness, and the obtained tar-like ester was dissolved in 10 parts by weight of methanol, and a methanol solution of 0.1 parts by weight of concentrated hydrochloric acid and 0.6 parts by weight of sodium tetraphenylborate was added dropwise. For 1 hour, and the precipitated dye was filtered off and dried to obtain 1.1 parts by weight (yield 74%) of dark red Rh08.

Example 1 Preparation and Evaluation of Color Conversion Film Coumarin 6 (manufactured by Aldrich), Rhodamine 6G (manufactured by Tokyo Chemical Industry), and Rh01 were each added to a sample bottle in an amount of 10 mg, and benzoguanamine resin (manufactured by Shinloich) was used as a binder resin. 1.5 g. This was dissolved with 1.5 g of ethyl cellosolve. A few drops of this solution were placed on a commercially available slide glass, and the slide glass was rotated using a spin coater at a rotation speed of 700 rpm for 20 seconds to form a film. This was dried on a hot plate at 80 ° C. for 15 minutes to produce a color conversion film (hereinafter abbreviated as RCCM). The thickness of the produced color conversion film was measured using a surface roughness meter (DEKTAK3030). A few drops of an inert liquid Fluorinert (manufactured by 3M) were applied on a glass substrate of the organic EL device, and RCCM was bonded on the substrate of the organic EL device. The organic EL element was driven to emit light, and the blue light output through the RCCM was measured (emission luminance and CIE chromaticity coordinates) using a colorimeter (CS100 manufactured by Minolta). As a result, the film thickness was 23.5 n.
m, the converted luminance is 48 cd / m ² , the conversion efficiency is 24%,
The chromaticity coordinates were (0.60, 0.36). The light emission luminance and CIE chromaticity coordinates of the organic EL element as a light source are 200
cd / m ² (0.16, 0.25).

Examples 2 to 16 In Example 1, Rh02 to Rh were used instead of Rh01.
A color conversion film was prepared in the same manner as in Example 1 except that No. 16 was used, and a blue organic EL device light source of 200 cd / m ² (0.
16, 0.24). The results are shown in Table 1. Examples 17 to 20 In Example 1, Rh17 to Rh2 were used instead of Rh01.
A color conversion film was prepared and evaluated in the same manner as in Example 1 except that the amount of the binder resin was changed from 1.5 g to 1.2 g. The results are shown in Table 1. Comparative Examples 1 and 2 A color conversion film was prepared and evaluated in the same manner as in Example 1, except that Rhodamine B (manufactured by Aldrich) was used instead of Rh01. The results are shown in Table 1.

[0058]

[Table 1]

As can be seen from the above results, in the color conversion film of the present invention, the concentration quenching of the dye is suppressed by the steric hindrance substituent, which is remarkably compared with the conventional color conversion film RCCM using rhodamine B dye. It has high color conversion efficiency. Example 21 Production of Organic EL Element First, a transparent anode of indium tin oxide coated on glass was provided. About 7 indium tin oxide
50 angstroms thick, glass 25 mm
× 75 mm × 1.1 mm in size. This was put into a vacuum evaporation apparatus (manufactured by Nippon Vacuum Engineering Co., Ltd.), and about 10 ^-6
The pressure was reduced to torr. MTDATA was deposited thereon to a thickness of 600 angstroms. The deposition rate at this time is 2
Angstrom / sec. Next, NPD was deposited to a thickness of 200 Å. The deposition rate at this time was 2 Å / sec. Next, Alq and Rh01 were co-evaporated to form a light emitting layer having a thickness of 400 angstroms. At this time, the deposition rate of Alq is 5
0 Å / sec, and the deposition rate of Rh01 was 1 Å / sec. 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 is applied to the obtained device, the current density becomes
It was 2.8 mA / cm ² , and orange-red light emission with a luminance of 90 cd / m ² was obtained. The luminous efficiency was 1.2 lumen / W.

MTDATA

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NPD

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Alq

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Comparative Example 3 An organic EL device was manufactured in the same manner as in Example 1, except that Rh610 was used instead of Rh01. When a voltage of 8 V was applied to the obtained element, the current density was 2.9 mA / cm ² and red light emission with a luminance of 34 cd / m ² was obtained. The luminous efficiency was 0.46 lumen / W.

Rh610

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[0065]

The rhodamine dye used in the color conversion film and the organic EL device of the present invention has a cycloalkyl group or a heterocyclo ring as a steric hindrance group, so that association of the dye is suppressed, and as a result, concentration quenching occurs. Is suppressed. Therefore, the color conversion film of the present invention using such a rhodamine dye can convert blue light into red light with high conversion efficiency by combining with a light emitting source such as an organic EL element. Further, the organic EL device of the present invention in which the above rhodamine-based dye is contained in at least one of the organic compound layers can emit red light with high efficiency.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshiharu Iinuma 1-1-1, Kamitobakamichocho-cho, Minami-ku, Kyoto-shi, Kyoto (72) Inventor Yoshio Hironaka 1280, Kamiizumi, Kamiizumi, Sodegaura-shi, Chiba 3K007 AB03 AB04 BB00 BB06 CA01 CA02 CA05 CB01 DA00 DB03 EB00 FA01 4H056 BA02 BB05 BC01 BD01 BF26F BF27F BF33 BF38E FA05

Claims (11)

[Claims] 1. A color conversion film comprising a resin in which a rhodamine dye having at least one cycloalkyl group and / or heterocyclo ring as a steric hindrance group is dispersed. 2. It has at least one cycloalkyl group.
The rhodamine dye represented by the general formula (I):(Where R¹~ R^FourMeans that at least one is unsubstituted
Is a cycloalkyl group having 3 to 12 ring carbon atoms having a substituent
And the remainder is a hydrogen atom, an alkyl group having 1 to 32 carbon atoms or
Unsubstituted or substituted ants having 6 to 24 nuclear carbon atoms
A group represented by R ^FiveIs a hydrogen atom, an alkyl group having 1 to 32 carbon atoms.
Killed group, unsubstituted or substituted ring carbon number 3-1
2 cycloalkyl groups, unsubstituted or substituted
Represents an aryl group or an aralkyl group having 6 to 24 core carbon atoms
And -COOR^FiveIs substituted on the benzene ring to which
May be introduced, and A^-Indicates a counter ion
You. 2. The color conversion according to claim 1, which is a compound represented by the formula:
film. 3. The rhodamine dye having at least one heterocyclo ring is represented by the general formula (II): (Wherein, R ^{6 to} R ⁹ are such that at least one pair of R ⁶ and R ⁷ and R ⁸ and R ⁹ is bonded to each other via a saturated or unsaturated linking group having 3 to 9 carbon atoms. , N as a heteroatom, the remainder being a hydrogen atom, an alkyl group having 1 to 32 carbon atoms, an unsubstituted or substituted cycloalkyl group having 3 to 12 carbon atoms, or an unsubstituted or substituted cycloalkyl group. R ⁵ is a hydrogen atom, an alkyl group having 1 to 32 carbon atoms, an unsubstituted or substituted ring carbon atom having 3 to 12 carbon atoms,
A cycloalkyl group, an unsubstituted or substituted aryl group having 6 to 24 nuclear carbon atoms or an aralkyl group,
A substituent may be introduced into the benzene ring to which —COOR ⁵ is bonded, and A ⁻ represents a counter ion. The color conversion film according to claim 1, which is a compound represented by the formula: In the general formula (II), a saturated or unsaturated linking group having 3 to 9 carbon atoms is represented by the following formula: 4. The color conversion film according to claim 3, wherein the color conversion film is selected from the groups represented by: 5. The color conversion film according to claim 1, wherein the resin is at least one selected from a urea resin, a benzoguanamine resin and a melamine resin. 6. The color conversion film according to claim 1, wherein the wavelength of the light from the light emitting source is converted by combining the light with the light emitting source. 7. The color conversion film according to claim 6, wherein the light emitting source is an organic electroluminescence device. 8. An organic electroluminescence device comprising a pair of electrodes and an organic compound layer having at least an organic light emitting layer sandwiched between the pair of electrodes, wherein at least one of the organic compound layers is a cycloalkyl as a steric hindrance group. An organic electroluminescent device comprising a rhodamine dye having at least one group and / or heterocyclo ring. 9. Having at least one cycloalkyl group
The rhodamine-based dye has the general formula (I):(Where R¹~ R^FourMeans that at least one is unsubstituted
Is a cycloalkyl group having 3 to 12 ring carbon atoms having a substituent
And the remainder is a hydrogen atom, an alkyl group having 1 to 32 carbon atoms or
Unsubstituted or substituted ants having 6 to 24 nuclear carbon atoms
A group represented by R ^FiveIs a hydrogen atom, an alkyl group having 1 to 32 carbon atoms.
Killed group, unsubstituted or substituted ring carbon number 3-1
2 cycloalkyl groups, unsubstituted or substituted
Represents an aryl group or an aralkyl group having 6 to 24 core carbon atoms
And -COOR^FiveIs substituted on the benzene ring to which
May be introduced, and A^-Indicates a counter ion
You. 8. The organic element according to claim 7, which is a compound represented by the formula:
Castroluminescence element. 10. The rhodamine-based dye having at least one heterocyclo ring is represented by the following general formula (II): (Wherein, R ^{6 to} R ⁹ are such that at least one pair of R ⁶ and R ⁷ and R ⁸ and R ⁹ is bonded to each other via a saturated or unsaturated linking group having 3 to 9 carbon atoms. , N as a heteroatom, the remainder being a hydrogen atom, an alkyl group having 1 to 32 carbon atoms, an unsubstituted or substituted cycloalkyl group having 3 to 12 carbon atoms, or an unsubstituted or substituted cycloalkyl group. R ⁵ is a hydrogen atom, an alkyl group having 1 to 32 carbon atoms, an unsubstituted or substituted ring carbon atom having 3 to 12 carbon atoms,
A cycloalkyl group, an unsubstituted or substituted aryl group having 6 to 24 nuclear carbon atoms or an aralkyl group,
A substituent may be introduced into the benzene ring to which —COOR ⁵ is bonded, and A ⁻ represents a counter ion. The organic electroluminescent device according to claim 7, which is a compound represented by the formula: 11. In the general formula (II), a saturated or unsaturated linking group having 3 to 9 carbon atoms is represented by the following formula: The organic electroluminescent device according to claim 7, wherein the organic electroluminescent device is selected from the groups represented by the following formulae.