JP2014060418A - Solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar battery module having a wavelength-conversion type solar battery sealing sheet arranged so that the reduction in weather resistance is suppressed while the power generation efficiency is increased.SOLUTION: A solar battery module comprises a solar battery cell and a wavelength-conversion type solar battery sealing sheet. The wavelength-conversion type solar battery sealing sheet is provided on the side of a light-receiving surface of the solar battery cell in contact therewith, and includes a dispersant resin and resin particles having therein a europium complex; the content of UV absorber except the europium complex is 0.15 pts.mass or less to 100 pts.mass of the dispersant resin.

Description

  The present invention relates to a solar cell module having a wavelength conversion type solar cell encapsulating sheet. More specifically, the present invention relates to a solar cell module having a wavelength conversion type solar cell encapsulating sheet that does not contain an ultraviolet absorber other than a fluorescent material.

  Silicon crystal solar cells generally have low sensitivity to ultraviolet light. Therefore, attempts have been made to increase the conversion efficiency by increasing the light in the wavelength region with high sensitivity by converting the light in the ultraviolet region into the wavelength in the visible region or the near infrared region. So far, solar cells have been developed to emit light in the wavelength region that contributes greatly to power generation by converting the wavelength of ultraviolet or infrared light that contributes less to power generation in the sunlight spectrum using fluorescent materials. Many methods for providing the light receiving surface have been proposed (see, for example, Patent Documents 1 to 5).

In addition, a method for incorporating a rare earth complex, which is a fluorescent substance, in a sealing material has been proposed (see, for example, Patent Document 6).
Conventionally, ethylene-vinyl acetate copolymers imparted with thermosetting properties have been widely used as transparent sealing agents for solar cells (see, for example, Patent Documents 7 and 8).

  For this sealant (also referred to as a filler), a resin mainly composed of ethylene vinyl acetate copolymer is used and contains an ultraviolet absorber.

  This UV absorber absorbs harmful UV rays in the irradiated light and converts them into innocuous heat energy within the molecule, which activates the active species that initiate photodegradation in the polymer. To prevent.

  Commonly used UV absorbers include benzophenone, benzotriazole, triazine, salicylic acid, cyanoacrylate, etc., especially to prevent high photodegradation of ethylene-vinyl acetate copolymer. Because of this, benzophenone UV absorbers are widely used.

JP 2003-243682 A JP 2003-218379 A Japanese Patent Publication No. 08-004147 JP 2001-094128 A JP 2001-352091 A JP 2006-303033 A JP 2005-126708 A JP 2008-159856 A

  However, since the transparent sealing film for solar cells contains an ultraviolet absorber, the power generation efficiency has been reduced. This is because there is a portion where the absorption spectrum of the ultraviolet absorber slightly overlaps with the sensitivity spectrum of the solar cell. However, a sealing film to which no ultraviolet absorber is added has a problem that it has low weather resistance and is not practical.

  This invention is made | formed in view of the above problems, The objective is to provide the wavelength conversion type solar cell sealing sheet which improves a power generation efficiency and does not reduce a weather resistance.

  As a result of intensive investigations to solve the above problems, the present inventors have made the wavelength conversion type solar cell encapsulating sheet contain a dispersion medium resin and a fluorescent material having an absorption wavelength peak at 300 nm or more and 450 nm or less, and By setting the content of the ultraviolet absorber other than the fluorescent material to 0.15 parts by mass or less with respect to 100 parts by mass of the dispersion medium resin, the power generation efficiency is improved and the fluorescent substance itself acts as a UV absorber. As a result, the present invention has been completed.

The wavelength conversion type solar cell encapsulating sheet is converted into light having a wavelength that contributes to power generation from light in the ultraviolet region that contributes less to solar power generation in the incident sunlight by the phosphor contained in the encapsulant. At the same time, it absorbs ultraviolet light and prevents the active species at the start of photodegradation of the dispersion medium resin contained in the sealing sheet from being excited, thereby achieving both high power generation efficiency and weather resistance. It is done.
Therefore, the wavelength conversion type solar cell encapsulating sheet of the present invention has higher power generation efficiency and a reduction in weather resistance than the conventional wavelength conversion type solar cell encapsulating sheet.
That is, the present invention is as follows.
<1> solar cells,
The resin cell is provided in contact with the light-receiving surface side of the solar battery cell, and includes resin particles containing a dispersion medium resin and a europium complex. The content of the UV absorber other than the europium complex is 0. A wavelength conversion type solar cell encapsulating sheet that is 15 parts by mass or less;
A solar cell module.
<2> The solar cell module according to <1>, wherein the resin particles are a polymer of a vinyl compound.
<3> The solar cell module according to <1> or <2>, wherein the resin particles are obtained by emulsion polymerization.
<4> The sun according to any one of <1> to <3>, wherein the dispersion medium resin includes at least one selected from the group consisting of (meth) acrylic acid ester resins and ethylene-vinyl acetate copolymers. Battery module.

  The wavelength conversion type solar cell encapsulating sheet of the present invention includes a dispersion medium resin and a fluorescent material having an absorption wavelength peak at 300 to 450 nm, and the content of an ultraviolet absorber other than the fluorescent material is the dispersion medium resin. It is 0.15 mass part or less with respect to 100 mass parts. The fluorescent material is preferably a europium complex.

  Moreover, the solar cell module of this invention has a photovoltaic cell and the said wavelength conversion type solar cell sealing sheet provided in the light-receiving surface side of this solar cell.

  ADVANTAGE OF THE INVENTION According to this invention, the wavelength conversion type solar cell sealing sheet and solar cell module which improve a power generation efficiency and do not reduce a weather resistance are provided.

It is a schematic sectional drawing which shows an example of a solar cell module.

  Hereinafter, embodiments of the present invention will be described in detail. In the present specification, “to” indicates a range including the numerical values described before and after the minimum and maximum values, respectively.

<Wavelength conversion solar cell encapsulating sheet>
The wavelength conversion type solar cell encapsulating sheet of the present invention is used on the light receiving surface side of a solar cell module. The wavelength conversion type solar cell encapsulating sheet of the present invention includes a dispersion medium resin and a fluorescent material having an absorption wavelength peak at 300 to 450 nm, and the content of an ultraviolet absorber other than the fluorescent material is the dispersion medium resin. It is 0.15 mass part or less with respect to 100 mass parts.

(Fluorescent substance)
The fluorescent material used in the present invention has an absorption wavelength peak at 300 to 450 nm. From the viewpoint of effectively preventing the active species at the start of photodegradation of the polymer contained in the wavelength conversion type solar cell encapsulating sheet from being excited, the fluorescent material used in the present invention has an absorption wavelength of 300 to 450 nm. It shall have a peak.
The fluorescent substances used in the present invention may be used singly or in combination of two or more.

Suitable fluorescent materials used in the present invention include rare earth metal organic complexes. Of these, a europium complex or a samarium complex is preferable, and a europium complex is more preferable.
By using a europium complex as the fluorescent material, a solar cell module having high power generation efficiency can be realized. The europium complex converts light in the ultraviolet region into light in the red wavelength region with high wavelength conversion efficiency, and the converted light contributes to power generation in the solar battery cell.

  The europium complex needs a molecule to be a ligand in addition to the central element europium (Eu), but in the present invention, the type of the ligand is not limited, so long as it is a molecule that forms a complex with europium. Either may be sufficient.

As an example of a fluorescent substance made of such a europium complex, a rare earth complex such as Eu (TTA) ₃ phen can be used. For the production method of Eu (TTA) ₃ Phen, for example, the method disclosed in Masaya Mitsuishi, Shinji Kikuchi, Tokuji Miyashita, Yutaka Amano, J. Mater. Chem. 2003, 13, 285-2879 can be referred to.

In the present invention, the ligand of the complex is not limited, but as the neutral ligand, carboxylic acid, nitrogen-containing organic compound, nitrogen-containing aromatic heterocyclic compound, β-diketone, or phosphine oxide is used. preferable.
Formula as the ligand of the rare earth ^complexes: R 1 COCHR ² COR ³ (wherein, ^{R 1} represents an aryl group, an alkyl group, a cycloalkyl group, a cycloalkylalkyl group, an aralkyl group, or substituted versions thereof, ^{R 2} is , A hydrogen atom, an alkyl group, a cycloalkyl group, a cycloalkylalkyl group, an aralkyl group or an aryl group, and R ³ represents an aryl group, an alkyl group, a cycloalkyl group, a cycloalkylalkyl group, an aralkyl group or a substituent thereof. (Beta) -diketone represented by this may be contained.

  Specific examples of β-diketones include acetylacetone, perfluoroacetylacetone, benzoyl-2-furanoylmethane, 1,3-bis (3-pyridyl) -1,3-propanedione, benzoyltrifluoroacetone, and benzoylacetone. 5-chlorosulfonyl-2-thenoyltrifluoroacetone, di (4-bromo) benzoylmethane, dibenzoylmethane, d, d-dicamphorylmethane, 1,3-dicyano-1,3-propanedione, p- Di (4,4,5,5,6,6,6-heptafluoro-1,3-hexanedinoyl) benzene, 4,4'-dimethoxydibenzoylmethane, 2,6-dimethyl-3,5-heptane Dione, dinaphthoylmethane, dipivaloylmethane, di (perfluoro-2-propoxypropionyl) methane 1,3-di (2-thienyl) -1,3-propanedione, 3- (trifluoroacetyl) -d-camphor, 6,6,6-trifluoro-2,2-dimethyl-3,5-hexane Dione, 1,1,1,2,2,6,6,7,7,7-decafluoro-3,5-heptanedione, 6,6,7,7,8,8,8-heptafluoro-2 , 2-dimethyl-3,5-octanedione, 2-furyltrifluoroacetone, hexafluoroacetylacetone, 3- (heptafluorobutyryl) -d-camphor, 4,4,5,5,6,6,6- Heptafluoro-1- (2-thienyl) -1,3-hexanedione, 4-methoxydibenzoylmethane, 4-methoxybenzoyl-2-furanoylmethane, 6-methyl-2,4-heptanedione, 2-naphtho Iltriful Loacetone, 2- (2-pyridyl) benzimidazole, 5,6-dihydroxy-10-phenanthroline, 1-phenyl-3-methyl-4-benzoyl-5-pyrazole, 1-phenyl-3-methyl-4- (4 -Butylbenzoyl) -5-pyrazole, 1-phenyl-3-methyl-4-isobutyryl-5-pyrazole, 1-phenyl-3-methyl-4-trifluoroacetyl-5-pyrazole, 3- (5-phenyl- 1,3,4-oxadiazol-2-yl) -2,4-pentanedione, 3-phenyl-2,4-pentanedione, 3- [3 ′, 5′-bis (phenylmethoxy) phenyl]- 1- (9-phenanthyl) -1-propane-1,3-dione, 5,5-dimethyl-1,1,1-trifluoro-2,4-hexanedione, 1-pheni Ru-3- (2-thienyl) -1,3-propanedione, 3- (t-butylhydroxymethylene) -d-camphor, 1,1,1-trifluoro-2,4-pentanedione, 1,1 , 1,2,2,3,3,7,7,8,8,9,9,9-tetradecafluoro-4,6-nonanedione, 2,2,6,6-tetramethyl-3,5- Heptanedione, 4,4,4-trifluoro-1- (2-naphthyl) -1,3-butanedione, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 2, 2,6,6-tetramethyl-3,5-heptanedione, 2,2,6,6-tetramethyl-3,5-octanedione, 2,2,6-trimethyl-3,5-heptanedione, , 2,7-trimethyl-3,5-octanedione, 4,4,4-triflu B-1- (thienyl) -1,3-butanedione (TTA), 1,3-diphenyl-1,3-propanedione, benzoylacetone, dibenzoylacetone, diisobutyroylmethane, dibiparoylmethane 3-methylpentane-2,4-dione, 2,2-dimethylpentane-3,5-dione, 2-methyl-1,3-butanedione, 1,3-butanedione, 3-phenyl-2,4-pentane Dione, 1,1,1-trifluoro-2,4-pentanedione, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 2,2,6,6-tetramethyl-3 , 5-heptanedione, 3-methyl-2,4-pentanedione, 2-acetylcyclopentanone, 2-acetylcyclohexanone, 1-heptafluoropropyl-3-t-butyl-1, Examples include 3-propanedione, 1,3-diphenyl-2-methyl-1,3-propanedione, 1-ethoxy-1,3-butanedione, and the like.

  Nitrogen-containing organic compounds, nitrogen-containing aromatic heterocyclic compounds, and phosphine oxides of neutral ligands of rare earth complexes include, for example, 1,10-phenanthroline, 2-2'-bipyridyl, 2-2'-6, 2 "-terpyridyl, 4,7-diphenyl-1,10-phenanthroline, 2- (2-pyridyl) benzimidazole, triphenylphosphine oxide, tri-n-butylphosphine oxide, tri-n-octylphosphine oxide, tri- Examples thereof include n-butyl phosphate.

More preferably, the fluorescent material is encapsulated in resin particles. Although there is no restriction | limiting in particular as a monomer compound which comprises the said resin particle, From a viewpoint of scattering suppression of light, it is preferable that it is a vinyl compound.
In addition, as a method of encapsulating the fluorescent substance in the resin particles, a commonly used method can be used without any particular limitation. For example, it can be prepared by preparing a mixture of monomer compounds constituting the fluorescent substance and resin particles and polymerizing the mixture. Specifically, for example, by preparing a mixture containing a fluorescent substance and a vinyl compound, and polymerizing the vinyl compound using a radical polymerization initiator, the fluorescent material for wavelength conversion is configured as resin particles containing the fluorescent substance. can do. In the present invention, the “fluorescent material for wavelength conversion” refers to a material obtained by polymerizing a vinyl compound containing a fluorescent material.

  In the present invention, the vinyl compound is not particularly limited as long as it is a compound having at least one ethylenically unsaturated bond, and an acrylic monomer, a methacrylic monomer, which can be converted into a vinyl resin, particularly an acrylic resin or a methacrylic resin when polymerized. An acrylic oligomer, a methacryl oligomer, etc. can be used without a restriction | limiting in particular. In the present invention, an acrylic monomer, a methacryl monomer, and the like are preferable.

  Examples of the acrylic monomer and the methacrylic monomer include acrylic acid, methacrylic acid, and alkyl esters thereof, and other vinyl compounds that can be copolymerized with these may be used in combination. A combination of the above can also be used.

  Examples of the alkyl acrylate ester and the alkyl methacrylate ester include, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate. Acrylic acid unsubstituted alkyl ester and methacrylic acid unsubstituted alkyl ester; dicyclopentenyl (meth) acrylate; tetrahydrofurfuryl (meth) acrylate; benzyl (meth) acrylate; α, β-unsaturated carboxylic acid to polyhydric alcohol (For example, polyethylene glycol di (meth) acrylate (having 2 to 14 ethylene groups), trimethylolpropane di (meth) acrylate, trimethylolpropylene) N-tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, trimethylolpropane propoxytri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, polypropylene glycol di (meth) Acrylate (having 2 to 14 propylene groups), dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, bisphenol A polyoxyethylene di (meth) acrylate, bisphenol A dioxyethylene di ( Meth) acrylate, bisphenol A trioxyethylene di (meth) acrylate, bisphenol A decaoxyethylene di (meth) acrylate, etc.); Compounds obtained by adding an α, β-unsaturated carboxylic acid to a group-containing compound (for example, trimethylolpropane triglycidyl ether triacrylate, bisphenol A diglycidyl ether diacrylate, etc.); a polyvalent carboxylic acid (for example, phthalic anhydride) Acid) and a substance having a hydroxyl group and an ethylenically unsaturated group (for example, β-hydroxyethyl (meth) acrylate); acrylic acid or alkyl ester of methacrylic acid (for example, (meth) acrylic acid methyl ester, ( (Meth) acrylic acid ethyl ester, (meth) acrylic acid butyl ester, (meth) acrylic acid 2-ethylhexyl ester); urethane (meth) acrylate (eg, tolylene diisocyanate and 2-hydroxyethyl (meth) acrylic ester) reaction A reaction product of trimethylhexamethylene diisocyanate, cyclohexanedimethanol and 2-hydroxyethyl (meth) acrylic acid ester); an acrylic acid-substituted alkyl ester or a methacrylic acid in which a hydroxyl group, an epoxy group, a halogen group or the like is substituted on these alkyl groups Acid-substituted alkyl ester; and the like.

  Examples of other vinyl compounds that can be copolymerized with acrylic acid, methacrylic acid, alkyl acrylate ester, or alkyl methacrylate ester include acrylamide, acrylonitrile, diacetone acrylamide, styrene, vinyl toluene, and the like. These vinyl monomers can be used alone or in combination of two or more.

  As the vinyl compound in the present invention, at least one selected from alkyl acrylates and alkyl methacrylates is preferably used, and at least one selected from methyl acrylate, methyl methacrylate, ethyl acrylate, and ethyl methacrylate. More preferably using seeds

  In the present invention, it is preferable to use a radical polymerization initiator in order to polymerize the vinyl compound. As the radical polymerization initiator, a commonly used radical polymerization initiator can be used without particular limitation. For example, a peroxide etc. are mentioned preferably.

  Examples of the peroxide include ammonium sulfate, sodium persulfate, potassium persulfate, isobutyl peroxide, α, α′bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, and di-n-propylperoxide. Oxydicarbonate, di-s-butylperoxydicarbonate, 1,1,3,3-tetramethylbutylneodecanoate, bis (4-tert-butylcyclohexyl) peroxydicarbonate, 1-cyclohexyl-1- Methylethylperoxyneodecanoate, di-2-ethoxyethylperoxydicarbonate, bis (ethylhexylperoxy) dicarbonate, t-hexylneodecanoate, dimethoxybutylperoxydicarbonate, bis (3-methyl- 3-methoxybutyl par Oxy) dicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1, 1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, succinic peroxide, 2,5-dimethyl-2,5-di (2-ethylhexanoyl) hexane, 1-cyclohexyl-1- Methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, 4-methylbenzoyl peroxide, t-butylperoxy-2-ethylhexanoate, m-toluonoylbenzoyl Peroxide, benzoyl peroxide, -Butyl peroxyisobutyrate, 1,1-bis (t-butylperoxy) 2-methylcyclohexane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1 -Bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexanone, 2,2 -Bis (4,4-dibutylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) cyclododecane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylper Oxy-3,5,5-trimethylhexanoate, t-butyl peroxylaurate, 2,5-dimethyl 2,5-bis (m-toluoylperoxy) hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl -2,5-bis (benzoylperoxy) hexane, t-butylperoxyacetate, 2,2-bis (t-butylperoxy) butane, t-butylperoxybenzoate, n-butyl-4,4-bis (T-butylperoxy) valerate, di-t-butylperoxyisophthalate, α, α′bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-bis (T-butylperoxy) hexane, t-butylcumyl peroxide, di-t-butyl -Oxy, p-menthane hydroperoxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne, diisopropylbenzene hydroperoxide, t-butyltrimethylsilyl peroxide, 1,1,3,3- Tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroperoxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, and the like can be used.

  The usage-amount of a radical polymerization initiator can be suitably selected according to the kind of said vinyl compound, the refractive index of the resin particle formed, etc., and is used by the usage-amount normally used. Specifically, for example, it can be used at 0.1 to 15 parts by mass, preferably 0.5 to 10 parts by mass with respect to the vinyl compound.

  The fluorescent material for wavelength conversion in the present invention is a mixture of the above fluorescent substance and vinyl compound, if necessary, radical polymerization initiators such as peroxides, chain transfer agents such as n-octanethiol, etc. It is obtained by dissolving or dispersing in a vinyl compound and polymerizing it. There is no restriction | limiting in particular as a mixing method, For example, what is necessary is just to carry out by stirring.

  It is desirable that the content of the fluorescent material in the wavelength conversion type solar cell encapsulating sheet is appropriately adjusted depending on the type of the fluorescent material. In general, the content of the fluorescent substance in the wavelength conversion type solar cell encapsulating sheet is preferably 0.00001 to 30 parts by mass with respect to 100 parts by mass of the dispersion medium resin. The amount is more preferably 0.0005 to 20 parts by mass, and still more preferably 0.0001 to 10 parts by mass. By setting it as 0.0001 mass part or more, the efficiency of wavelength conversion becomes more sufficient, and the fall of the light quantity which reaches | attains a photovoltaic cell can be suppressed more by setting it as 10 mass parts or less.

(UV absorber)
In addition, the wavelength conversion type solar cell encapsulating sheet of the present invention has a content of an ultraviolet absorber other than the above-described fluorescent material (hereinafter sometimes simply referred to as “ultraviolet absorber”) of 100 mass of the dispersion medium resin. The amount is 0.15 parts by mass or less based on parts. The luminous efficiency of a solar cell module can be improved by making the content rate of a ultraviolet absorber into 0.15 mass part or less.

  The term “ultraviolet absorber” as used herein refers to a substance other than the fluorescent substance, which has an absorption wavelength peak at 300 to 450 nm. Further, “the content is 0.15 parts by mass or less with respect to 100 parts by mass of the dispersion medium resin” includes a case where the ultraviolet absorber is not included.

  The content of the ultraviolet absorber in the wavelength conversion type solar cell encapsulating sheet is 0.15 parts by mass or less, more preferably 0.1 parts by mass or less, substantially 100 parts by mass of the dispersion medium resin, More preferably, no ultraviolet absorber is contained.

(Dispersion medium resin)
The wavelength conversion type solar cell encapsulating sheet of the present invention contains a dispersion medium resin for dispersing the fluorescent substance or the wavelength converting fluorescent material. Specific examples of the dispersion medium resin include acrylic resin, polycarbonate resin, polystyrene resin, polyolefin resin, polyvinyl chloride resin, polyether sulfone resin, polyarylate resin, polyvinyl acetal resin, epoxy resin, silicone resin, Examples thereof include fluororesins and copolymers thereof.
The said dispersion medium resin may be used individually by 1 type or in combination of 2 or more types.

  Examples of the acrylic resin include (meth) acrylic acid ester resins. Examples of the polyolefin resin include polyethylene and polypropylene. Examples of the polyvinyl acetal resin include polyvinyl formal, polyvinyl butyral (PVB resin), and modified PVB.

  Moreover, (meth) acrylic acid ester resin means what has a structural unit derived from acrylic acid ester or methacrylic acid ester, As acrylic acid alkylester or methacrylic acid alkylester, methyl acrylate, methacrylic acid, for example Acrylic acid unsubstituted alkyl esters or methacrylic acid unsubstituted alkyl esters such as methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and alkyls thereof Examples include acrylic acid-substituted alkyl esters and methacrylic acid-substituted alkyl esters in which the group is substituted with a hydroxyl group, an epoxy group, a halogen group, or the like.

The acrylic acid ester or methacrylic acid ester is preferably an alkyl ester having 1 to 10 carbon atoms of acrylic acid or methacrylic acid, and more preferably an alkyl ester having 2 to 8 carbon atoms.
Specific examples of the acrylic ester or methacrylic ester include ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, methyl acrylate, Examples thereof include ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, cyclohexyl acrylate, phenyl acrylate, and benzyl acrylate.

  The (meth) acrylic acid ester resin may be a copolymer using an unsaturated monomer copolymerizable with an acrylic acid ester or a methacrylic acid ester.

Examples of the unsaturated monomer include unsaturated acids such as methacrylic acid and acrylic acid; styrene, α-methylstyrene, acrylamide, diacetone acrylamide, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, and the like. And two or more of them can be used as necessary.
These unsaturated monomers can be used alone or in combination of two or more.

Among these, (meth) acrylic acid ester resins include methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, and n-butyl methacrylate. What has the structural unit derived from is preferable, and what has the structural unit derived from methyl methacrylate from a durable or versatile viewpoint is more preferable.
Examples of the copolymer resin include (meth) acrylic acid ester-styrene copolymer, ethylene-vinyl acetate copolymer (hereinafter abbreviated as “EVA”), and the like.

  EVA is preferable in terms of moisture resistance, cost, and versatility, and (meth) acrylic ester resin is preferable in terms of durability and surface hardness. Furthermore, the combined use of EVA and (meth) acrylic ester resin is more preferable from the viewpoint of combining the advantages of both.

  As EVA, when the whole EVA is 100 parts by mass, the content of vinyl acetate units is preferably 10 to 50 parts by mass, and preferably 20 to 35 parts by mass to the sealing material of the rare earth complex. It is preferable from the point of uniform dispersibility.

  Commercially available EVA resins that do not contain UV absorbers can be applied. Examples of commercially available products include Ultrasen 634 manufactured by Tosoh Corporation, EVAFLEX manufactured by Mitsui DuPont Polychemical Co., Ltd., and Asahi Kasei. Examples include Suntech EVA manufactured by Chemicals, UBE EVA copolymer manufactured by Ube Maruzen Polyethylene, Evaate manufactured by Sumitomo Chemical Co., and Novatec EVA manufactured by Nippon Polyethylene.

  In addition, it is estimated that the solar EVA which is an ethylene vinyl acetate copolymer resin (EVA) solar cell sealing material made from Mitsui Chemicals Fabro contains 0.25 mass part of ultraviolet absorbers with respect to 100 mass parts of this resin, and Bridgestone. EVASAFE which is an EVA resin sealing material manufactured by the company is estimated to contain 0.21 part by mass with respect to 100 parts by mass of the resin.

  When EVA and methyl methacrylate are used in combination, the content of EVA is preferably 50 parts by mass or more and more preferably 70 parts by mass or more with respect to 100 parts by mass of the total amount of EVA and methyl methacrylate. preferable.

Further, the dispersion medium resin may be a resin having a crosslinked structure by adding a crosslinkable monomer.
Examples of the crosslinking monomer include dicyclopentenyl (meth) acrylate; tetrahydrofurfuryl (meth) acrylate; benzyl (meth) acrylate; a compound obtained by reacting a polyhydric alcohol with an α, β-unsaturated carboxylic acid ( For example, polyethylene glycol di (meth) acrylate (having 2 to 14 ethylene groups), trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, Trimethylolpropane propoxytri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, polypropylene glycol di (meth) acrylate (propylene group Of dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, bisphenol A polyoxyethylene di (meth) acrylate, bisphenol A dioxyethylene di (meth) acrylate, Bisphenol A trioxyethylene di (meth) acrylate, bisphenol A deoxyoxyethylene di (meth) acrylate, etc.); a compound obtained by adding an α, β-unsaturated carboxylic acid to a glycidyl group-containing compound (for example, trimethylolpropane) Triglycidyl ether triacrylate, bisphenol A diglycidyl ether diacrylate, etc.); a substance having a polyvalent carboxylic acid (for example, phthalic anhydride), a hydroxyl group and an ethylenically unsaturated group (for example, β-hydroxyethyl) Esterified product with (meth) acrylate); alkyl ester of acrylic acid or methacrylic acid (for example, (meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, (meth) acrylic acid butyl ester, (meth) acrylic acid 2 -Ethylhexyl ester); urethane (meth) acrylate (for example, reaction product of tolylene diisocyanate and 2-hydroxyethyl (meth) acrylic ester, trimethylhexamethylene diisocyanate, cyclohexanedimethanol and 2-hydroxyethyl (meth) acrylic acid) A reaction product with an ester, etc.);

Particularly preferred crosslinking monomers include trimethylolpropane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and bisphenol A polyoxyethylene dimethacrylate.
In addition, the said crosslinkable monomer is used individually by 1 type or in combination of 2 or more types.

  The resin can be polymerized by adding a thermal polymerization initiator or a photopolymerization initiator to the monomer and heating or irradiating with light, or can have a crosslinked structure.

Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane-3, and di-t-. Butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, α, α′-bis (t-butylperoxyisopropyl) benzene, n-butyl-4,4-bis (t-butylperoxy) butane, 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-butylperoxy) cyclohexane, 1,1- Bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, t-butylperoxybenzate, benzoyl peroxide and the like can be mentioned.
The content of the thermal polymerization initiator is sufficient up to 5 parts by mass with respect to the dispersion medium resin.

  As the photopolymerization initiator, a photoinitiator that generates a free radical by ultraviolet light or visible light is preferable, for example, benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, benzoin phenyl ether, Benzophenones such as benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), N, N′-tetraethyl-4,4′-diaminobenzophenone, benzyldimethyl ketal (Ciba Japan Chemicals) Manufactured by Irgacure 651), benzyl ketals such as benzyl diethyl ketal, 2,2-dimethoxy-2-phenylacetophenone, p-tert-butyldichloroacetophenone, p-dimethylamino Acetophenones such as cetophenone, xanthones such as 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, or hydroxycyclohexyl phenyl ketone (Ciba Specialty Chemicals, Irgacure 184), 1- (4-isopropylphenyl) -2-vitroxy-2-methylpropan-1-one (Ciba Japan Chemicals, Darocur 1116), 2-hydroxy-2-methyl-1-phenylpropan-1-one (Merck, Darocur 1173) These are used alone or in combination of two or more.

Examples of the photoinitiator that can be used as a photopolymerization initiator include 2,4,5-triallylimidazole dimer, 2-mercaptobenzoxazole, leucocrystal violet, and tris (4-diethylamino-2-methyl). Combinations with phenyl) methane and the like can also be mentioned. In addition, although it does not itself have photoinitiating properties, it can be used in combination with the above-mentioned substances to provide a sensitizer system with better photoinitiating performance as a whole, such as triethanolamine for benzophenone. Secondary amines can be used.
The content of the photopolymerization initiator is sufficient up to 5 parts by mass with respect to the dispersion medium resin.

  The weight average molecular weight of the dispersion medium resin is preferably 10,000 to 300,000 from the viewpoint of coating properties and coating strength.

  In addition to the above, the wavelength conversion type solar cell encapsulating sheet of the present invention includes a coupling agent, a plasticizer, a flame retardant, an antioxidant, a light stabilizer, a rust inhibitor, a processing aid, and a colorant as necessary. Etc. may be contained.

(Wavelength conversion solar cell encapsulating sheet)
The wavelength conversion type solar cell encapsulating sheet of the present invention can be manufactured using a known technique. For example, a method of melt-kneading at least the fluorescent material and the dispersion medium resin, and other additives as necessary, to form a sheet, or adding the fluorescent material into a sheet after varnishing the resin A method for removing the solvent can be used.
Specifically, for example, two release sheets are opposed to each other via a spacer, the melt-kneaded composition is applied to a gap formed between the two release sheets, and hot pressed from both sides. A sheet can be formed.

  The thickness of the wavelength conversion type solar cell encapsulating sheet is preferably 10 μm to 1000 μm, and more preferably 400 μm to 600 μm.

  The wavelength conversion type solar cell encapsulating sheet of the present invention reduces light loss due to spectrum mismatch, and further improves light utilization efficiency by converting ultraviolet light to highly sensitive wavelength light. , Power generation efficiency can be improved. Further, in the wavelength conversion type solar cell encapsulating sheet of the present invention, the fluorescent material particles also serve as a UV absorber, and an EVA resin containing a UV absorber other than the fluorescent material (for example, product name, manufactured by Mitsui Fabro Co., Ltd., trade name) : The same weather resistance as solar eva).

<Solar cell module>
The solar cell module of this invention has a solar cell and the said wavelength conversion type solar cell sealing sheet provided in the light-receiving surface side of this solar cell at least. FIG. 1 is a schematic cross-sectional view showing an example of a solar cell module.
In the solar cell module of FIG. 1, a protective layer 12 is provided on the light receiving surface side of the solar battery cell 10, and a back film 14 is provided on the back surface side. Furthermore, the sealing layer 16 is provided between the protective layer 12 and the solar battery cell 10, and the wavelength conversion type solar battery sealing sheet is used as the sealing layer 16. In addition, a back surface sealing layer 18 is provided between the back film 14 and the solar battery cell 10. The back surface sealing layer 18 is not particularly limited as long as the solar battery cell 10 can be sealed. For example, in the above-described wavelength conversion type solar battery sealing sheet, one that does not add the fluorescent material is applied. Is also possible.

  Although not shown in FIG. 1, the solar cell module of the present invention may further include a member that is normally provided in the solar cell module, such as an antireflection film.

  Since the solar cell module of the present invention is provided with the wavelength conversion type solar cell encapsulating sheet on the light receiving surface side, it is possible to suppress a decrease in weather resistance while improving the power generation efficiency.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[Example 1]
(Synthesis of phosphor particles)
First, a fluorescent material was synthesized. 200 mg of 4,4,4-trifluoro-1- (thienyl) -1,3-butanedione (TTA) was dissolved in 7 ml of ethanol, and 1.1 ml of 1M sodium hydroxide was added thereto and mixed. 6.2 mg of 1,10-phenanthroline dissolved in 7 ml of ethanol was added to the previous mixed solution and stirred for 1 hour, and then a 3.5 ml aqueous solution containing 103 mg of EuCl ₃ · 6H ₂ O was added to obtain a precipitate. . This was filtered off, washed with ethanol, and dried to obtain the fluorescent substance Eu (TTA) ₃ Phen.

(Preparation of resin composition for wavelength conversion)
Using 0.3 parts by mass of Eu (TTA) ₃ Phen obtained above as a fluorescent substance, 60 parts by mass of methyl methacrylate as a vinyl compound, and 0.012 parts by mass of n-octanethiol as a chain transfer agent, The monomer mixture was prepared by mixing and stirring. Further, 300 parts by mass of ion-exchanged water, 3.65 parts by mass of sodium alkylbenzene sulfonate manufactured by Kao Corporation and G-15 as a surfactant were added, and the monomer mixture described above was added thereto, followed by reflux tube, nitrogen flow The flask was stirred and kept at 60 ° C., 0.03 parts by mass of potassium persulfate as a radical polymerization initiator was added, emulsion polymerization was carried out for 4 hours, and finally the temperature was raised to 90 ° C. Was completed. The fluorescent material for wavelength conversion obtained here is in the form of particles having a primary particle diameter of about 100 nm, and is appropriately post-treated with isopropyl alcohol, etc., filtered, dried, sieved appropriately, A fluorescent material for wavelength conversion was obtained.

(Adjustment of wavelength conversion resin composition)
100 g of ethylene-vinyl acetate resin (EVA): Ultrasen 634 (not containing an ultraviolet absorber) manufactured by Tosoh Corporation as a transparent dispersion medium resin, a peroxide thermal radical polymerization initiator manufactured by Arkema Yoshitomi Corporation (In this example, it also functions as a crosslinking agent): 1.5 g of Luperox 101, 0.5 g of silane coupling agent manufactured by Toray Dow Corning Co., Ltd .: 0.5 g of SZ6030, and the particulate wavelength conversion obtained above 2 g of the fluorescent material was kneaded with a roll mill at 90 ° C. to obtain a wavelength conversion resin composition.

(Preparation of wavelength conversion type solar cell encapsulating sheet)
About 30 g of the wavelength conversion resin composition obtained above is sandwiched between release sheets, a 0.6 mm thick stainless steel spacer is used, and a heat plate is adjusted to 80 ° C., using a press to convert the sheet into a wavelength conversion type A solar cell encapsulating sheet was obtained. This wavelength conversion type solar cell encapsulating sheet does not contain an ultraviolet absorber.

(Preparation of solar cell encapsulating sheet for back surface)
The solar cell encapsulating sheet for the back surface was produced in the same manner as the production of the wavelength converting solar cell encapsulating sheet, but without adding the wavelength converting fluorescent material.

(Production of solar cell module)
On the tempered glass (manufactured by Asahi Glass Co., Ltd.) as protective glass, the wavelength conversion type solar cell encapsulating sheet is placed, and on the solar cell so that the electromotive force can be taken out, A solar cell encapsulating sheet for the back surface and a PET film (trade name: A-4300, manufactured by Toyobo Co., Ltd.) were sequentially placed as a back film and laminated using a vacuum laminator to produce a solar cell module of Example 1.

[Comparative Example 1]
(Preparation of solar cell module containing UV absorber)
Tempered glass (manufactured by Asahi Glass Co., Ltd.) as protective glass, ethylene vinyl acetate copolymer resin (EVA) solar cell encapsulant (manufactured by Mitsui Chemicals Fabro Co., Ltd., trade name: Solar Eva, UV) 0.25 parts by mass of the absorbent, 0.04 parts by mass of the light stabilizer, 0.4 parts by mass of the crosslinking aid, and 0.5 parts by mass of the silane coupling agent), solar cell ( The EVA resin (0.6 mm thickness) and the polyethylene terephthalate (PET) film (A-4300, manufactured by Toyobo Co., Ltd.) are stacked in this order as the back film and laminated using a vacuum laminator. A solar cell module of Comparative Example 1 was produced.

[Comparative Example 2]
(Production of solar cell module not containing fluorescent material)
Reinforced glass (manufactured by Asahi Glass Co., Ltd.) as protective glass, solar cell sealing film for back surface of Example 1 as sealing material, solar battery cell (light receiving surface facing down), solar cell sealing film for back surface Then, a polyethylene terephthalate (PET) film (A-4300, manufactured by Toyobo Co., Ltd.) was laminated in this order as a back film, and laminated using a vacuum laminator to produce a solar cell module of Comparative Example 2.

<Evaluation of solar cell characteristics>
As a simulated solar ray, using a solar simulator (Wacom Denso Co., Ltd., WXS-155S-10, AM1.5G), current voltage characteristics using an IV curve tracer (Eihiro Seiki Co., Ltd., MP-160), The cell state before module sealing and after module sealing were measured, and the difference between them was evaluated.
Note that Jsc (short-circuit current density), Isc (short-circuit current), Voc (open-circuit voltage), Pm (maximum output), Ipm (maximum output operating current), and Vpm (maximum output operating voltage) indicating power generation performance as a solar cell. , F.F. (curve factor), and h _in (solar cell module conversion efficiency) are obtained by measuring in accordance with JIS-C-8913 and JIS-C-8914.
Table 1 below shows the measurement results of the solar cell modules of Example 1 and Comparative Example 1.

As seen in Table 1, the conversion efficiency η _in (%) was 0.56% in Example 1 when Comparative Example 1 was −0.02%. Therefore, it can be seen that the conversion efficiency is improved in the module of Example 1 compared to Comparative Example 1.

<Evaluation of weather resistance of solar cell module>
For the solar cell modules of Example 1 and Comparative Examples 1 and 2, a strong energy xenon weather meter (XEL-1WN, manufactured by Suga Test Instruments Co., Ltd.) was used, and FF (curve factor) was changed to an IV curve tracer ( Using an Eiko Seiki Co., Ltd. product, MP-160), measurements were made before light exposure, 168 hours after light exposure, and 336 hours after light exposure, and the values were compared and evaluated.
The measurement results are shown in Table 2.

As can be seen from Table 2, in Comparative Example 2, the F.E. F. The rate of decrease of 6.8% was 6.8%, whereas in Example 1 and Comparative Example 1, it was 0.5% or less. In addition, as above-mentioned, the conversion efficiency (eta) _in (%) of the comparative example 1 was largely inferior compared with Example 1. FIG.

Claims (4)

Solar cells,
The resin cell is provided in contact with the light-receiving surface side of the solar battery cell, and includes resin particles containing a dispersion medium resin and a europium complex. The content of the UV absorber other than the europium complex is 0. A wavelength conversion type solar cell encapsulating sheet that is 15 parts by mass or less;
A solar cell module.   The solar cell module according to claim 1, wherein the resin particles are a polymer of a vinyl compound.   The solar cell module according to claim 1, wherein the resin particles are obtained by emulsion polymerization.   The solar cell module according to any one of claims 1 to 3, wherein the dispersion medium resin includes at least one selected from the group consisting of (meth) acrylic acid ester resins and ethylene-vinyl acetate copolymers.