JP2009108126A - Luminescent medium-forming composition, luminescent medium, organic el device, display device, and method for forming luminescent medium film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a luminescent medium-forming composition which suppresses the surface deterioration of a luminescent semiconductor nanocrystal and can easily disperse the luminescent semiconductor nanocrystal in a transparent resin composition at high concentration. <P>SOLUTION: A protective compound contained in the luminescent medium-forming composition has a reactive silicone group at the α-end and a cyclic ether group at the ω-end, and the reactive silicone group and the cyclic ether group are bonded by an ether bond. It is possible to suppress the occurrence of defects on the surface of the luminescent semiconductor nanocrystal and can maintain a quantum yield by allowing the reactive silicone group to be adsorbed into the surface of the luminescent semiconductor nanocrystal. Since surface modification becomes unnecessary, it is possible to facilitate handling and prevent the production process from being complicated. A cyclic ether group and an ether bond can increase the compatibility of the luminescent semiconductor nanocrystal in a transparent resin composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a composition for forming a luminescent medium, a luminescent medium, an organic EL element, a display device, and a method for forming a luminescent medium film.

The luminescent semiconductor nanocrystal is a semiconductor made into ultrafine particles (with a diameter of 10 nm), and exhibits a specific light absorption / emission characteristic due to an electron confinement effect (quantum size effect).
Since this light-emitting semiconductor nanocrystal does not cause concentration quenching unlike ordinary fluorescent dyes, a high fluorescence quantum yield can be realized and high device efficiency can be expected. In addition, ultrafine particles (nano-size) are made finer than ordinary fluorescent pigments or phosphor particles (micro-size), so light scattering can be suppressed and transparency can be increased, and high contrast of the device can be achieved. realizable. In addition, by changing the particle size with the same material and creating sharp light emission of any wavelength, it is possible to realize abundant color alignment and high efficiency.
Since the luminescent semiconductor nanocrystals have these characteristics, the luminescent semiconductor nanocrystals are dispersed in a transparent resin to produce a luminescent medium, which is applied to optoelectronic devices such as display devices, displays, TVs, and lighting. It is expected that.

By the way, luminescent semiconductor nanocrystals are nano-sized ultrafine particles, and have a very large surface area per unit and are active. Even if other semiconductors or coating agents are used to cover the light-emitting semiconductor nanocrystals, it is difficult to completely cover the light-emitting semiconductor nanocrystals, causing defects or being easily oxidized by the influence of oxygen, resulting in light emission. The (fluorescence) quantum yield is significantly reduced.
As a result, although the light-emitting semiconductor nanocrystal has the above-described excellent characteristics, the composition for forming a light-emitting medium and the formed light-emitting medium are not stable and the light-emitting performance of the light-emitting medium is also reduced. There was a problem that.

As a means for solving such a problem, it is known that surface degradation can be suppressed by coating the surface of a light-emitting semiconductor nanocrystal with an inert material. For example, Patent Document 1 discloses a technique for coating the surface of a light-emitting semiconductor nanocrystal with glass.
As another solution, Patent Document 2 discloses a light-emitting medium in which a light-emitting semiconductor nanocrystal is dispersed in a transparent resin.

JP 2000-275180 A Japanese translation of PCT publication No. 2002-510866

However, in the configuration as in Patent Document 1, although the stability of the luminescent semiconductor nanocrystal is improved by coating the surface of the luminescent semiconductor nanocrystal with a strong material, it is dispersed in the transparent resin composition to be dispersed. It becomes difficult to do. Therefore, in order to uniformly disperse the light-emitting semiconductor nanocrystals in the transparent resin composition, it is necessary to apply a surface modification to improve the dispersion performance on the outer shell of a stronger material, and the manufacturing process becomes complicated. There is a problem that. In addition, there is a problem that the control of dispersibility of the light-emitting semiconductor nanocrystal in another medium becomes complicated.
In the configuration as in Patent Document 2, the concentration of the light-emitting semiconductor nanocrystal that can be uniformly dispersed in the transparent resin composition is low, and it is impossible to obtain a sufficient light emission intensity in the thin-film light-emitting medium. That is, in order to obtain a sufficient light emission intensity in the thin film light emitting medium, it is necessary to disperse the light emitting semiconductor nanocrystals at a high concentration in the transparent resin composition.
From the above, it is desired to develop a technique for easily dispersing a light-emitting semiconductor nanocrystal in a transparent resin composition at a high concentration while suppressing surface degradation of the light-emitting semiconductor nanocrystal.

  An object of the present invention is to solve such a problem, and while suppressing surface degradation of the luminescent semiconductor nanocrystal, the luminescent semiconductor nanocrystal can be easily added at a high concentration in the transparent resin composition. Dispersible composition for forming a luminescent medium, luminescent medium, organic EL element, display device, and luminescent medium film forming method are provided.

  The composition for forming a light emitting medium of the present invention is a composition for forming a light emitting medium for forming a light emitting medium composed of light emitting semiconductor nanocrystals, comprising: a transparent resin composition; and the light emitting semiconductor nanocrystals. And a protective compound having a reactive silicone group at the α-terminal and a cyclic ether group at the ω-terminal, and joining the reactive silicone group and the cyclic ether group with an ether bond. It is characterized by.

According to the present invention, a protective compound having a reactive silicone group at the α-terminal is applied.
The reactive silicone group can be synthesized as a substitute or adduct by dealkylsilylation with various organic compounds or siloxane by sol-gel reaction. In particular, siloxane compounds can be applied to organic-inorganic hybrids, and compatibility and affinity for both organic and inorganic compounds can be controlled by selecting functional groups.
Therefore, the reactive silicone group reacts on the surface of the light-emitting semiconductor nanocrystal, so that the protective compound is immobilized on the surface of the nanocrystal, and the light-emitting semiconductor nanocrystal is removed from the occurrence of surface defects due to oxidation or the like. Can be protected.
That is, the reactive silicone group acts to realize a strong coordination of the protective compound to the luminescent semiconductor nanocrystal.
Furthermore, as the protective compound, a compound having a cyclic ether group at the ω end is applied.
The cyclic ether group has relatively high compatibility with various resins or various solvents, and is stable thermally and optically. In addition, it is known that ring-opening polymerization proceeds when a cyclic ether group is heated in the presence of a thermal polymerization initiator.
In other words, by introducing a cyclic ether group, copolymerization with the matrix resin monomer proceeds in the thermosetting resin, and a crosslinked structure between the matrix resin and the luminescent semiconductor nanocrystal is formed in the luminescent medium film. Can be expected. The formation of this cross-linked structure can be expected to improve film homogeneity and film strength.
That is, the cyclic ether group contributes to the compatibility between the light-emitting semiconductor nanocrystal and the resin composition, and particularly in thermosetting resins, it acts to improve the homogeneity and strength of the light-emitting medium film. It is.
In the protective compound, those using an ether bond as a linking group for linking the α terminal group and the ω terminal group are applied.
Conventionally, PEG (polyethylene glycol) or the like is used as a surface modification, but such a surface modification alone is not sufficient from the viewpoint of surface coating, although the compatibility with the solvent or resin used is improved. After application of the composition, the quantum efficiency was lowered by drying and forming a film. In the present invention, by using a protective compound having an ether bond, in addition to improving compatibility with solvents and resins, it is possible to suppress a decrease in quantum efficiency by the effect of a reactive silicone group and a cyclic ether group. it can.
That is, the ether bond as a linking group is only a function of linking a reactive silicone group that performs a coordinating function to a light-emitting semiconductor nanocrystal and a cyclic ether group that performs a solubilizing function to a resin composition. It aims at contributing to the compatibility to a resin composition.
For this reason, these reactive silicone groups, cyclic ether groups, and protective compounds having an ether bond are coordinated to the surface of the light-emitting semiconductor nanocrystal, thereby suppressing the surface degradation of the light-emitting semiconductor nanocrystal. A composition for forming a light-emitting medium in which semiconductor nanocrystals are dispersed at a high concentration in a transparent resin composition can be provided.

In the composition for forming a light emitting medium of the present invention, the protective compound preferably has a structure represented by the following general formula (1).
(R ¹ ) _x (R ² ) _3-x Si-L _y -R ³ (1)
(R ¹ is an alkoxy group having 1 to 3 carbon atoms, R ² is an alkyl group having 1 to 3 carbon atoms or a hydrogen atom, L is an oxyalkylene group having 1 to 4 carbon atoms, and R ³ is a cyclic group having 2 to 10 carbon atoms. An oxyalkyl group, x = 0-3, y = 1-2000)

  Furthermore, in the composition for forming a luminescent medium of the present invention, the ratio of the protective compound to the luminescent semiconductor nanocrystal is preferably 1% by mass or more and 50% by mass or less.

According to this invention, the ratio with respect to the luminescent semiconductor nanocrystal of a protective compound is set to 1 mass% or more and 50 mass% or less.
Here, when the ratio of the protective compound to the luminescent semiconductor nanocrystal is less than 1% by mass, the ratio of the protective compound is too small, and thus the effect of suppressing surface defects of the luminescent semiconductor nanocrystal and the transparent resin composition are reduced. There exists a possibility that the effect which improves a meltability may become small. On the other hand, when it is larger than 50% by mass, the transparency and strength of the luminescent medium produced with the luminescent medium forming composition may be lowered.
From the above, it is possible to provide a composition for forming a luminescent medium that has the effect of suppressing the surface degradation of the luminescent semiconductor nanocrystal and the effect of dispersing the luminescent semiconductor nanocrystal at a high concentration. Furthermore, by using this composition for forming a luminescent medium, a luminescent medium having appropriate transparency and strength can be produced.

  In the composition for forming a light-emitting medium of the present invention, the transparent resin composition preferably contains a thermosetting resin.

According to this invention, the transparent resin composition contains a thermosetting resin.
For this reason, the cyclic ether group of a protective compound can be made to act as a polymeric group, and the transparency and intensity | strength of the film | membrane after thermosetting can be improved.

  The light emitting medium of the present invention is formed using the above-described composition for forming a light emitting medium.

  According to this invention, since the light-emitting medium includes the above-described composition for forming a light-emitting medium, a light-emitting medium in which the light-emitting semiconductor nanocrystals are uniformly dispersed at a high concentration in a transparent resin and the fluorescence yield is maintained high. Can be formed.

  In the luminescent medium of the present invention, it is preferable that visible light is re-emitted by absorbing light emitted from the illuminant.

  According to the present invention, since the light emission from the light emitter can be converted into visible light by the light emitting medium, light emission of a desired color can be created.

  The organic EL device of the present invention has a pair of electrodes, a plurality of organic thin films between the pair of electrodes, a light emitting layer that emits light by charge recombination energy, and absorbs light from the light emitting layer. And the above-described light emitting medium that emits light again.

  According to the present invention, since the light emitter is an organic electroluminescence element (organic EL element), it can be effectively used for a thin-film planar display and illumination due to the above-described effects.

  The display device of the present invention is characterized by using the organic EL element described above.

Here, examples of the light emitter of the display device include EL (electroluminescence), LED (light emitting diode), VFD (fluorescent display tube), PDP (plasma display panel), fluorescent lamp, and cold cathode tube.
According to the present invention, the light emitting medium can give a light emission color that does not exist in the light emitter, or a light emission color obtained by mixing the light of the light emitter and the light emission of the light emitting medium, for example, white.
Therefore, it is possible to provide a display device that exhibits the same effect as described above.

  The light emitting medium film forming method of the present invention is characterized in that a film of a light emitting medium is formed using a solution in which the above-described composition for forming a light emitting medium is dispersed.

  According to the present invention, since a solution in which the composition for forming a light emitting medium is dispersed is applied, for example, in addition to a casting method, a spin coating method, a bar coating method, a pattern is required, a photolithography method, a screen The film can be easily formed by a known method such as a printing method or an inkjet method.

  Hereinafter, embodiments of the present invention will be described.

[Configuration of composition for forming light emitting medium]
First, the structure of the composition for forming a light emitting medium will be described.
The composition for forming a light emitting medium is used for forming a light emitting medium. This composition for forming a luminescent medium is configured to contain a transparent resin composition, a luminescent semiconductor nanocrystal, a protective compound, and other various solvents. Each of these materials will be described in detail below.

(Luminescent semiconductor nanocrystal)
Examples of the light-emitting semiconductor nanocrystal include ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdMnS, CdSe, CdMnSe, CdTe, CdMnTe, HgS, HgSe, HgTe, InP, InAs, InSb, InN, GaN, GaP, GaAs, Examples include GaSb, TiO ₂ , WO ₃ , PbS, PbSe, MgTe, AlAs, AlP, AlSb, AlS, Ge, Si, CuInS ₂ , CuInSe ₂ , InGaP, and the like.
Further, semiconductor nanocrystals doped with the following transition metal ions are also included.
That is, a metal chalcogenide such as ZnS, ZnSe, CdS, or CdSe doped with transition metal ions such as Eu ²⁺ , Eu ³⁺ , Ce ³⁺ , Tb ³⁺ , or Cu ²⁺ can be used.
As the core of the luminescent semiconductor nanocrystal of the present invention, it is preferable to apply a chalcopyrite semiconductor nanocrystal such as a III-V compound semiconductor nanocrystal such as InP or CuInS ₂ or CuInSe ₂ .

The light-emitting semiconductor nanocrystal is a semiconductor crystal obtained by making the semiconductor crystal ultrafine to the nanometer order, and preferably has a particle size of 20 nm or less, more preferably 10 nm or less.
In light-emitting semiconductor nanocrystals, the surface of the nanocrystal surface is oxidized with metal oxides such as silica, organic substances such as long-chain alkyl groups, phosphoric acid, etc., in order to prevent S and Se from being extracted. It may be modified.
Furthermore, nanoparticles in which the surface of the nanoparticles is covered with another semiconductor called a shell are more preferable in terms of stability and fluorescence. The surface of the shell may be further coated with a metal oxide such as silica or titania.
The above light-emitting semiconductor nanocrystals may be used alone or in combination of two or more.

(Protected compounds)
The protective compound is an organic compound characterized in that it has a reactive silicone group at the α-terminal and a cyclic ether group at the ω-terminal, and these are joined by an ether bond.
Specifically, it is an organic compound having a structure represented by the following general formula (2).
(R ¹ ) _x (R ² ) _3-x Si-L _y -R ³ (2)

Here, in the general formula (2), R ¹ is an alkoxy group having 1 to 3 carbon atoms, R ² is an alkyl group having 1 to 3 carbon atoms or a hydrogen atom, L is an oxyalkylene group having 1 to 4 carbon atoms, R ³ is a cyclic oxyalkyl group having 2 to 10 carbon atoms, and x = 0 to 3 and y = 1 to 2000.
The ratio of the protective compound to the luminescent semiconductor nanocrystal is preferably 1% by mass or more and 50% by mass or less. More preferably, they are 1 mass% or more and 40 mass% or less, More preferably, they are 1 mass% or more and 30 mass% or less.

This protective compound is an organic compound having a chain structure and has a reactive silicone group at the α-terminal.
The reactive silicone group reacts with the nanocrystal surface and has an effect of suppressing the occurrence of defects on the nanocrystal surface.
More preferably, for the purpose of improving the reactivity of the reactive silicone group, the protective compound is strongly coordinated to the nanocrystal surface by performing a heat treatment or chemical reaction after the treatment with the present protective compound. However, its protection capability is expected to improve.

Examples of the reactive silicone group include the following.
Trimethoxysilyl group, triethoxysilyl group, tri (n-propoxy) silyl group, tri (i-propoxy) silyl group, dimethoxysilyl group, diethoxysilyl group, di (n-propoxy) silyl group, di (i- (Propoxy) silyl group, methoxysilyl group, ethoxysilyl group, n-propoxysilyl group, i-propoxysilyl group.
Dimethoxymethylsilyl group, dimethoxyethylsilyl group, dimethoxy (n-propyl) silyl group, dimethoxy (i-propyl) silyl group, diethoxymethylsilyl group, diethoxyethylsilyl group, diethoxy (n-propyl) silyl group, diethoxy (I-propyl) silyl group, di (n-propoxy) methylsilyl group, di (n-propoxy) ethylsilyl group, di (n-propoxy) (n-propyl) silyl group, di (n-propoxy) (i-propyl) ) Silyl group, di (i-propoxy) methylsilyl group, di (i-propoxy) ethylsilyl group, di (i-propoxy) (n-propyl) silyl group, di (i-propoxy) (i-propyl) silyl group.
Methoxydimethylsilyl group, methoxydiethylsilyl group, methoxydi (n-propyl) silyl group, methoxydi (i-propyl) silyl group, ethoxydimethylsilyl group, ethoxydiethylsilyl group, ethoxydi (n-propyl) silyl group, ethoxydi (i -Propyl) silyl group, n-propoxydimethylsilyl group, n-propoxydiethylsilyl group, n-propoxydi (n-propyl) silyl group, n-propoxydi (i-propyl) silyl group, i-propoxydimethylsilyl group, i -Propoxydiethylsilyl group, i-propoxydi (n-propyl) silyl group, i-propoxydi (i-propyl) silyl group.
Methoxymethylethylsilyl group, methoxymethyl (n-propyl) silyl group, methoxymethyl (i-propyl) silyl group, methoxyethyl (n-propyl) silyl group, methoxyethyl (i-propyl) silyl group, methoxy (i- Propyl) (n-propyl) silyl group, ethoxymethylethylsilyl group, ethoxymethyl (n-propyl) silyl group, ethoxymethyl (i-propyl) silyl group, ethoxyethyl (n-propyl) silyl group, ethoxyethyl (i -Propyl) silyl group, ethoxy (i-propyl) (n-propyl) silyl group, (n-propoxy) methylethylsilyl group, (n-propoxy) methyl (n-propyl) silyl group, (n-propoxy) methyl (I-propyl) silyl group, (n-propoxy) ethyl (n-propyl) silyl , (N-propoxy) ethyl (i-propyl) silyl group, (n-propoxy) (i-propyl) (n-propyl) silyl group, (i-propoxy) methylethylsilyl group, (i-propoxy) methyl ( n-propyl) silyl group, (i-propoxy) methyl (i-propyl) silyl group, (i-propoxy) ethyl (n-propyl) silyl group, (i-propoxy) ethyl (i-propyl) silyl group, ( i-propoxy) (i-propyl) (n-propyl) silyl group.
Methoxymethylsilyl group, methoxyethylsilyl group, methoxy (n-propyl) silyl group, methoxy (i-propyl) silyl group, ethoxymethylsilyl group, ethoxyethylsilyl group, ethoxy (n-propyl) silyl group, ethoxy (i -Propyl) silyl group, n-propoxymethylsilyl group, n-propoxyethylsilyl group, n-propoxy (n-propyl) silyl group, n-propoxy (i-propyl) silyl group, i-propoxymethylsilyl group, i -Propoxyethylsilyl group, i-propoxy (n-propyl) silyl group, i-propoxy (i-propyl) silyl group.
Methoxysilyl group, ethoxysilyl group, n-propoxysilyl group, i-propoxysilyl group.
Trimethylsilyl group, triethylsilyl group, tri (n-propyl) silyl group, tri (i-propyl) silyl group, dimethylsilyl group, diethylsilyl group, di (n-propyl) silyl group, di (i-propyl) silyl group Methylsilyl group, ethylsilyl group, n-propylsilyl group, i-propylsilyl group.

On the other hand, this protective compound has a cyclic ether group at the ω-terminal.
The cyclic ether group plays a role of enhancing the compatibility with the transparent resin composition forming the composition for forming a luminescent medium, the solvent, and the like. By the action of the cyclic ether group, the light-emitting semiconductor nanocrystal can be uniformly dispersed in the transparent resin composition at a high concentration.
More preferably, when a thermosetting resin is used for the transparent resin composition, the cyclic ether group can also act as a polymerizable group.
In this case, by thermosetting in the presence of a thermal polymerization initiator, a resin monomer, a crosslinkable monomer, etc., the light emitting semiconductor nanocrystal and the resin matrix form a crosslinked structure after thermosetting, and in the composition film Improvement in transparency and strength can be expected.

The cyclic ether group is preferably a cyclic oxyalkyl group having 2 to 10 carbon atoms, specifically, an oxacyclopropyl group, an oxacyclobutyl group, an oxacyclopentyl group, an oxacyclohexyl group, an oxacycloheptyl group, an oxacyclo group. Octyl group, oxacyclononyl group, oxacyclodecyl group, 1,2-epoxycyclopentyl group, 1,2-epoxycyclohexyl group, 1,4-epoxycyclohexyl group, 1,2-epoxycycloheptyl group, 1,2- Epoxycyclooctyl group, 1,2-epoxycyclononyl group, 1,2-epoxycyclodecyl group, 1,8-epoxy-p-menthyl group, α-pinene oxide group, 1,2-epoxyethylbenzyl group, 1 , 3-Dihydroisobenzofuranyl group, 2,3-dihydrobenzofuranyl group 3,4-dihydro-1H-2-benzopyranyl group, 3,4-dihydro -2H- pyranyl group, dibenzofuranyl group, and the like.
Furthermore, this protective compound has an ether bond as a group that links the reactive silicone group at the α-terminus and the cyclic ether group at the ω-terminus.
The ether bond plays a role of enhancing the compatibility of the nanocrystal with the transparent resin composition forming the composition for forming a luminescent medium, and aims to improve the compatibilizing ability by a synergistic effect with the cyclic ether group.
The linking group having an ether bond is preferably a divalent linear oxyalkylene group such as an oxyethylene group represented by PEG. In addition to the oxyethylene group, examples include an oxymethylene group, an oxypropylene group, and an oxybutylene group.
As long as the performance of the composition containing nanocrystals (quantum yield, film transparency, etc.) does not deteriorate, two or more types of protection differing in reactive silicone groups, cyclic ether groups, or linking groups. You may mix and use a compound. Moreover, you may use the protective compound which contains 2 or more types of different functional groups in the same molecule regarding both or one of the reactive silicone group and the cyclic ether group.
For example, it is possible to form a composition film having a gradient composition in the thickness direction by using a mixture of two kinds of protective compounds having different linking group lengths and cyclic ether groups. By forming such a gradient composition film, it can be expected to be multifunctional by forming a laminated film.

(Transparent resin composition)
The transparent resin composition is a resin in which the light-emitting semiconductor nanocrystals are dispersed, and a thermoplastic resin, a thermosetting resin, or a photocurable resin can be used. Specifically, oligomeric or polymeric melamine resin, phenolic resin, alkyd resin, epoxy resin, polyurethane resin, maleic acid resin, polyamide resin, or polymethyl methacrylate, polyacrylate, polycarbonate, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxy Examples thereof include a copolymer containing, as a constituent component, a monomer that forms these, such as ethyl cellulose and carboxymethyl cellulose.
The transparent resin composition may contain a crosslinkable monomer for the purpose of improving the strength of the composition film and improving the adhesion to the substrate.

As the photocurable resin, acrylic acid or methacrylic acid-based photopolymerization type having a reactive vinyl group containing a photosensitizer, or photocrosslinking type such as polyvinyl cinnamate is usually used. In the case where a photosensitizer is not included, a thermosetting type may be used.
As these matrix resins, one type of resin may be used alone, or a plurality of types may be mixed and used.

Here, in particular, a thermosetting resin is preferable, including a block carboxylic acid, and more preferably including a block carboxylic acid and an epoxy compound.
Specifically, JP-A-4-218561 discloses a carboxylic acid block obtained by blocking a carboxyl group of a polybasic carboxylic acid with a vinyl-type double bond-containing compound, and a carboxylic acid regenerated from the carboxylic acid block. A one-part thermosetting resin containing a compound containing two or more reactive functional groups capable of chemically bonding with an acid is described. Since this thermosetting composition coexists in the thermosetting reaction system in a form in which the polybasic carboxylic acid is made into a block body and does not react with a reactive functional group such as an epoxy group, the storage stability is good. In JP-A-4-218561, it is described that this thermosetting resin can be used for paints, inks, adhesives, molded articles and the like, and is used as a protective compound for semiconductor nanocrystal light emitters. No consideration has been given.

(Solvent and others)
In addition to the above materials, a solvent can be added to the composition for forming a luminescent medium. Examples of the solvent include glycol ethers such as ethylene glycol monoethyl ether; glycol ether esters such as ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate (PGMEA); glycol oligomer ethers such as diethylene glycol monomethyl ether. Glycol glycol ether esters such as diethylene glycol monomethyl ether acetate; aliphatic carboxylic acids or acid anhydrides such as acetic acid, 2-ethylhexanoic acid and acetic anhydride; aliphatic or aromatic such as ethyl acetate and propyl benzoate; Dicarboxylic acid diesters such as diethyl carbonate; alkoxycarboxylic acid esters such as methyl 3-methoxypropionate Ketocarboxylic esters such as ethyl acetoacetate; halogenated carboxylic acids such as chloroacetic acid and dichloroacetic acid; alcohols or phenols such as ethanol, isopropanol and phenol; aliphatic or aromatic such as diethyl ether and anisole; Alkoxy ethers such as 2-ethoxyethanol and 1-methoxy-2-propanol; glycol oligomers such as diethylene glycol and tripropylene glycol; amino alcohols such as 2-diethylaminoethanol and triethanolamine; Alkoxy alcohol esters such as 2-ethoxyethyl acetate; Ketones such as acetone and methyl isobutyl ketone; Morpho such as N-ethylmorpholine and phenylmorpholine Down like; pentylamine, tripentylamine, aliphatic or aromatic amines such as aniline.
In addition, you may add a filler, surfactant, an antifoamer, a leveling agent, antioxidant, an antistatic agent etc. as needed.

[Method for producing composition for forming light emitting medium]
Next, the manufacturing method of the composition for light emitting medium formation is demonstrated.
A composition for forming a luminescent medium is prepared by mixing and dispersing a luminescent semiconductor nanocrystal, a transparent resin composition, and the antioxidant and an appropriate solvent using a known method such as a mill method or an ultrasonic dispersion method. Can be obtained.

[Method for producing luminescent medium]
Next, a method for manufacturing the light emitting medium will be described.
When the above-mentioned composition for forming a light-emitting medium is a known film forming method, for example, a casting method, a spin coating method, a bar coating method, or a pattern, a photolithography method, a screen printing method, an ink jet method, etc. A light emitting medium is manufactured by applying and printing on a support substrate.
The thickness of the luminescent medium is 0.1 μm to 1 mm, preferably 0.5 μm to 500 μm, more preferably 1 μm to 100 μm.
The material, particle size, and blending ratio with the transparent resin composition of the light-emitting semiconductor nanocrystals are optimal depending on the type of light source (illuminant) that excites the light-emitting medium or the optoelectronic device such as a display device, display, TV, or illumination It becomes.

〔Luminous body〕
There is no restriction | limiting in particular as a light-emitting body in this invention, For example, each light-emitting body, such as EL, LED, VFD, PDP, a fluorescent lamp, a cold cathode tube, can be mentioned, Among these elements, organic EL A device is preferred.
In the case of an organic EL element, as described above, high-efficiency and high-luminance blue light emission is realized, and since it is composed of an organic material, light emission of all colors can be achieved by designing the organic material. This is because expectations are high.
Even if the type of the illuminant is different, the light of the illuminant can be easily converted into visible light by overlapping the luminescent medium of the present invention at a position where the light emission of a certain color illuminant can be absorbed. .

[Effects of the embodiment]
(1) As a protective compound contained in the composition for forming a luminescent medium, it has a reactive silicone group at the α-terminal and a cyclic ether group at the ω-terminal, and a gap between the reactive silicone group and the cyclic ether group. What is joined by an ether bond is applied.
Therefore, by causing the reactive silicone group to be adsorbed on the surface of the luminescent semiconductor nanocrystal, it is possible to suppress the occurrence of defects on the surface of the luminescent semiconductor nanocrystal, and to maintain the quantum yield. In addition, since surface modification is not required, handling can be facilitated and complication of the manufacturing process can be prevented. Furthermore, the meltability of the luminescent semiconductor nanocrystal with respect to the transparent resin composition can be enhanced by the cyclic ether group and the ether bond.
Therefore, when manufacturing the composition for forming a luminescent medium, the luminescent semiconductor nanocrystal can be dispersed at a high concentration in the transparent resin composition while suppressing the surface deterioration of the luminescent semiconductor nanocrystal.

(2) The ratio of the protective compound to the luminescent semiconductor nanocrystal is set to 1% by mass or more and 50% by mass or less.
For this reason, the composition for light emitting medium formation which has the effect which can suppress the surface degradation of luminescent semiconductor nanocrystal, and the effect which disperse | distribute luminescent semiconductor nanocrystal with high concentration can be provided. Furthermore, by using this composition for forming a luminescent medium, a luminescent medium having appropriate transparency and strength can be produced.

  (3) If the transparent resin composition contains a thermosetting resin, the cyclic ether group of the protective compound can act as a polymerizable group, and the transparency and strength of the film after thermosetting can be increased.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not restrict | limited at all to the description content of these Examples.

[Synthesis Example 1]
(Synthesis of InP / ZnS nanocrystals)
J. et al. Am. Chem. Soc. 2005, 127, 11364, InP / ZnS nanocrystals were synthesized. The following is an overview.

{1. Synthesis of InP core}
In a 200 ml four-necked flask, 0.29 g of indium acetate, 0.69 g of myristic acid, and 40 ml of octadecene were weighed, and the flask was set on a mantle heater. A mechanical stirrer equipped with a glass stirring shaft and a Teflon (registered trademark) stirring blade was set on the main tube of the flask. A three-way cock was attached to one of the branch pipes and connected to a nitrogen line and a vacuum line. A rubber septum cap was attached to another branch pipe. Thermocouples were set on the remaining branch pipes.

And the inside of a flask was pressure-reduced to vacuum and it stirred at 120 degreeC for 2 hours. Then, it returned to atmospheric pressure with nitrogen gas, and raised temperature to 280 degreeC.
In a glove box purged with nitrogen, 1.4 g of a 10% hexane solution of tristrimethylsilylphosphine and 1 ml of octadecene were weighed into a sample bottle and sucked with a gas tight syringe.
A solution of the phosphine compound was injected all at once from the septum cap portion of the four-necked flask. After 5 seconds, 40 ml of octadecene was added, and the reaction temperature was rapidly lowered to 180 ° C. And stirring was continued at 180 degreeC for 2 hours.
After this stirring, the temperature was lowered to 50 ° C. and the pressure was reduced by a vacuum pump for 1 hour.
The reaction solution was taken out by returning to atmospheric pressure with nitrogen gas and lowering the temperature to room temperature, and the precipitate was removed by centrifugation (3000 rpm, 10 minutes). The supernatant was once stored in the glove box.

{2. Synthesis of InP / ZnS core-shell nanocrystals}
In a 200 ml four-necked flask, 1.48 g of zinc laurate, 0.11 g of sulfur, and 10 ml of octadecene were weighed. The flask was equipped with the same equipment as in the above-described synthesis of the InP core.
The inside of the flask was evacuated to a vacuum and stirred at 80 ° C. for 30 minutes. Thereafter, the pressure was returned to atmospheric pressure with nitrogen gas, and a solution of InP nanoparticles stored in a glove box was added, followed by further stirring at 80 ° C. under reduced pressure for 1.5 hours.
After this stirring, the pressure was returned to atmospheric pressure with nitrogen gas, and the temperature was raised to 140 ° C. And stirring was continued for 1.5 hours.
The temperature was lowered to room temperature, the reaction solution was taken out, and coarse particles and unreacted raw materials were removed by centrifugation (3000 rpm, 15 minutes).
The obtained nanoparticles had a fluorescence peak wavelength of 615 nm and a fluorescence quantum yield of 20%. These were measured using a quantum yield measuring device (C9920-02 type) manufactured by Hamamatsu Photonics.

{3. Surface modification and solvent dispersion of luminescent semiconductor nanocrystals}
A part of the octadecene solution of InP / ZnS nanoparticles obtained by the above synthesis was poured into ethanol to reprecipitate the nanoparticles. The solvent was removed by decantation and then vacuum-dried to obtain nanoparticles (51 mg).
Next, after dispersing the nanoparticles in 10 ml of xylene, 160 mg of 3-glycidyloxypropyl (dimethoxy) silane (molecular weight 220.34, manufactured by Tokyo Chemical Industry Co., Ltd.) was added and heated under reflux for 2 hours in a nitrogen atmosphere.
After heating to reflux and cooling to room temperature, the nanoparticles were reprecipitated by adding to acetonitrile. Thereafter, 60 mg of toluene was added to prepare a toluene dispersion of luminescent semiconductor nanocrystals.
The obtained nanoparticles had a fluorescence peak wavelength of 610 nm and a fluorescence quantum yield of 19%.

[Synthesis Example 2]
(Synthesis of block carboxylic acid-epoxy compound composition as transparent resin)
Based on JP 2001-350010 A and JP 2003-66223 A, a block carboxylic acid-epoxy compound composition was produced.

{1. Synthesis of main polymer (A))
In a four-necked flask equipped with a thermometer, a reflux condenser, a stirrer, and a dropping funnel, a solvent PGMEA (propylene glycol methyl ether acetate) that does not contain a hydroxyl group is added according to the mixing ratio in Table 1 of JP-A-2001-350010. 40 parts by weight were charged, heated with stirring, and heated to 80 ° C. Subsequently, at a temperature of 80 ° C., 28 parts by weight of GMA (glycidyl methacrylate), 22 parts by weight of CHMA (cyclohexyl methacrylate), 3.5 parts by weight of AIBN (2,2′-azobisisobutyronitrile), PGMEA 6.5 60 parts by weight of a mixture (parts dropped) of parts by weight was dropped at a constant rate from a dropping funnel over 2 hours. After completion of the dropping, the reaction was terminated when the temperature of 80 ° C. was maintained for 5 hours. Polymer (A) was obtained.

{2. Synthesis of Blocked Carboxylic Acid Compound (B)}
In a four-necked flask equipped with a thermometer, a reflux condenser, a stirrer, and a dropping funnel, 11 parts by weight of methyl ethyl ketone, 1,2,4-trimerit according to the blending ratio shown in Table 3 of JP-A-2003-66223 36 parts by weight of an acid (polybasic carboxylic acid) and 53 parts by weight of a blocking agent (n-propyl vinyl ether) were charged, heated while stirring and heated to 70 ° C. Next, stirring was continued while maintaining a temperature of 70 ° C., and the reaction was terminated when the acid value of the mixture became 5 or less, and the blocked carboxylic acid compound (B )was gotten.
Next, a Teflon (registered trademark) -covered rotor was placed in a sample bottle (capacity 200 ml) and placed on a magnetic stirrer. In this sample bottle, 57 parts by weight of the main polymer (A), 26 parts by weight of the blocked carboxylic acid compound (B), 15 parts by weight of a polyfunctional epoxy resin (jER157S70: manufactured by Japan Epoxy Resin Co., Ltd.), and halogen A free acidic catalyst (Nofcure LC-1: manufactured by NOF Corporation) was added and dissolved with sufficient stirring, and then a dilution solvent was added to adjust the viscosity. And after stirring and melt | dissolving, this was filtered and the block carboxylic acid-epoxy compound composition was obtained.

[Synthesis Example 3]
(Synthesis of glycidyl (polyethyleneoxy) trimethylsilane)
J. et al. Org. Chem. , 1996, 61, 8310, glycidyl (polyethyleneoxy) trimethylsilane was synthesized from O-allyloxy (polyethyleneoxy) trimethylsilane (manufactured by Gelest).

[Evaluation]
A composition for forming a light emitting medium was prepared by the procedure shown in Examples 1 to 4 and Comparative Examples 1 and 2, and a light emitting medium was manufactured using the composition for forming a light emitting medium. Then, the storage stability of the light emitting medium forming composition and the light emitting medium was evaluated.

(Composition for forming light emitting medium and method for producing light emitting medium)
{Example 1}
100 mg of the light-emitting semiconductor nanocrystal dispersion of Synthesis Example 1 and 131 mg of methyl methacrylate / methacrylic acid copolymer (Mw = 13,000) as a transparent resin are mixed and dispersed, and the composition for forming a luminescent medium of Example 1 is obtained. A product was prepared.
The luminescent medium forming composition of Example 1 immediately after preparation was applied to the entire surface of the substrate by spin coating in air, and the solvent was dried at 120 ° C. to form the luminescent medium of Example 1.

{Example 2}
A luminescent medium forming composition of Example 2 was prepared under the same conditions as in Example 1, except that 3-glycidyloxypropyl (dimethoxy) methylsilane was changed to glycidyl (polyethyleneoxy) trimethylsilane.
Moreover, the composition for forming a light emitting medium of Example 2 immediately after preparation was applied to the entire surface of the substrate by spin coating in air, and the solvent was dried at 120 ° C. to form the light emitting medium of Example 2.

{Example 3}
A light emitting medium forming composition of Example 3 was prepared under the same conditions as in Example 1, except that the transparent resin was 260 mg of a composition comprising a block carboxylic acid and an epoxy compound (solid content: 50% by weight). did.
In addition, the composition for forming a luminescent medium of Example 3 immediately after preparation was applied to the entire surface of the substrate by spin coating in air, the solvent was dried at 120 ° C., and the transparent resin was further thermally cured. 3 luminescent media were formed.

{Example 4}
In Example 2, the transparent resin was composed of 77 mg of methyl methacrylate / methacrylic acid copolymer (Mw = 13,000), 54 mg of pentaerythritol triacrylate, and 1.1 mg of Irgacure 907 (manufactured by Ciba Specialty Chemicals) A light emitting medium forming composition of Example 4 was prepared under the same conditions except for the above.
Further, the composition for forming a luminescent medium of Example 3 immediately after preparation was applied to the entire surface of the substrate by an air spin coating method. And the solvent was dried at 120 degreeC, and also the light emitting medium of Example 4 was formed by irradiating 300 mJ of ultraviolet rays with a wavelength of 365 nm to cure the transparent resin.

{Comparative Example 1}
In Example 1, the light emitting medium forming composition of Comparative Example 1 was prepared under the same conditions except that the protective compound was not used.
Moreover, the luminescent medium formation composition of the comparative example 1 immediately after preparation was apply | coated to the whole surface of the board | substrate by the spin coating method in air, and the luminescent medium of the comparative example 1 was formed by drying a solvent at 120 degreeC.

{Comparative Example 2}
A luminescent medium-forming composition of Comparative Example 2 was prepared under the same conditions as in Example 1, except that 3-glycidyloxypropyl (dimethoxy) methylsilane was changed to triethylsilanol.
Moreover, the luminescent medium of Comparative Example 2 was formed by applying the composition for forming a luminescent medium of Comparative Example 2 immediately after preparation to the entire surface of the substrate by spin coating in air and drying the solvent at 120 ° C.

(Evaluation methods)
First, the fluorescence quantum yield of the composition for forming a luminescent medium immediately after preparation was measured with a quantum yield measuring apparatus (C9920-02 type) manufactured by Hamamatsu Photonics. Further, air was sealed in the composition for forming a luminescent medium, which was sealed and stored at room temperature for 1 week in a dark place, and the fluorescence quantum yield was measured again.
Moreover, the fluorescence quantum yield of the luminescent medium immediately after formation was measured. Further, the luminescent medium was stored in the air for 1 week in the dark, and the fluorescence quantum yield was measured again.
The measurement results are shown in Table 1 below.
Moreover, the luminescent medium of Example 3, 4 was exposed to the acetone solvent, and the deterioration state was evaluated.

(Evaluation results)
As shown in Table 1, in the composition for forming a luminescent medium of Examples 1 and 3, there was no change in the fluorescence quantum yield, and no deterioration was observed. Moreover, in the composition for light emitting medium formation of Example 2, 4, the reduction | decrease of a fluorescence quantum yield is 2%, and hardly deteriorates.
On the other hand, in the composition for forming a light emitting medium of Comparative Examples 1 and 2, the decrease in the fluorescence quantum yield was 19% and 15%, which is greatly deteriorated.
In addition, in the luminescent media of Examples 1 and 3, the decrease in the fluorescence quantum yield was 1%, and in the luminescent media of Examples 2 and 4, the increase in the fluorescence quantum yield was 1%, which hardly deteriorates.
On the other hand, in the luminescent media of Comparative Examples 1 and 2, the decrease in the fluorescence quantum yield is 7% and 6%, which is greatly deteriorated.
From the above, by applying the protective compound of the present invention, the luminescent semiconductor nanocrystal is not easily oxidized by the influence of oxygen or the like, and the luminescent quantum efficiency of the luminescent medium forming composition and the luminescent medium is improved. It was confirmed that it could be kept high.

Moreover, although there is no big difference in the fluorescence quantum yield of the composition for light emitting medium formation of Examples 1-4 immediately after preparation and Comparative Examples 1-2, the light emitting medium of Examples 1-4 immediately after formation, and a comparative example There is a large difference in the fluorescence quantum yield between the light-emitting media of 1-2.
From the above, by applying the protective compound of the present invention, the concentration of the light-emitting semiconductor nanocrystal that can be uniformly dispersed in the transparent resin can be increased, and the light emission intensity of the light-emitting medium can be sufficiently obtained. It could be confirmed.

Furthermore, the luminescent media of Examples 3 and 4 did not dissolve at all even when exposed to acetone solvent.
From the above, it was confirmed that the chemical resistance of the luminescent medium can be improved by applying a thermosetting or photocurable resin as the transparent resin.

  The present invention can be effectively used for optoelectronic devices such as display devices, displays, televisions, and lighting.

Claims (9)

A composition for forming a light-emitting medium for forming a light-emitting medium composed of light-emitting semiconductor nanocrystals,
A transparent resin composition;
The light emitting semiconductor nanocrystal;
a protective compound having a reactive silicone group at the α-terminus and a cyclic ether group at the ω-terminus, and joining the reactive silicone group and the cyclic ether group with an ether bond;
A composition for forming a luminescent medium, comprising: The composition for forming a light-emitting medium according to claim 1,
The protective compound has a structure represented by the following general formula (1): (R ¹ ) _x (R ² ) _3-x Si-L _y -R ³ (1)
(R ¹ is an alkoxy group having 1 to 3 carbon atoms, R ² is an alkyl group having 1 to 3 carbon atoms or a hydrogen atom, L is an oxyalkylene group having 1 to 4 carbon atoms, and R ³ is a cyclic group having 2 to 10 carbon atoms. An oxyalkyl group, x = 0-3, y = 1-2000)
A composition for forming a light emitting medium. The composition for forming a light-emitting medium according to claim 1 or 2,
A ratio of the protective compound to the light-emitting semiconductor nanocrystal is 1% by mass or more and 50% by mass or less. In the composition for light emitting medium formation in any one of Claims 1-3,
The said transparent resin composition contains a thermosetting resin. The composition for light emitting medium formation characterized by the above-mentioned. A luminescent medium formed using the luminescent medium forming composition according to any one of claims 1 to 4. The luminescent medium according to claim 5,
A light-emitting medium characterized by absorbing light emitted from a light emitter and re-emitting visible light. A pair of electrodes;
A light emitting layer having a plurality of organic thin films between the pair of electrodes and emitting light by recombination energy of charges,
The light-emitting medium according to claim 5 or 6, which absorbs light from the light-emitting layer and emits light again.
An organic EL device comprising: A display device using the organic EL element according to claim 7. A method for forming a luminescent medium film, comprising forming a film of a luminescent medium using a solution in which the composition for forming a luminescent medium according to any one of claims 1 to 4 is dispersed.