JP2015118955A - Filler sheet for solar cell module and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filler sheet for solar cell module having high heat resistance, especially heat creep resistance, and wavelength conversion performance, and to provide a solar cell module manufactured using the filler sheet for solar cell module.SOLUTION: In a filler sheet A for solar cell module having more than two layers, the more than two layers includes at least outermost layers 2 on both sides and a wavelength conversion layer 1. The outermost layer 2 contains an ethylene-vinyl acetate copolymer, an organic peroxide, and a radical reactivity silane coupling agent. The wavelength conversion layer 1 contains ethylene-vinyl acetate copolymer, and a luminous body where a luminescent molecule and a self-aggregating molecule are bound.

Description

The present invention relates to a solar cell module filler sheet having high heat resistance, particularly high heat creep resistance, and also having wavelength conversion performance. Moreover, this invention relates to the solar cell module produced using this filler sheet for solar cell modules.

In recent years, solar cells have been attracting attention as a clean energy source as the awareness of environmental issues and energy issues has increased. Currently, solar cell modules having various forms have been developed and proposed. For example, a rigid solar cell module based on glass or the like, a flexible solar cell module based on a polyimide or polyester heat-resistant polymer material or a stainless thin film, and the like are known.

Such a solar cell module is generally composed of a transparent protective material, a filler sheet, a solar cell element as a photovoltaic element, a filler sheet, a back surface protective material, and the like.
Then, these members are cut into a desired shape in advance and then laminated, and these are manufactured by a method in which they are laminated and integrated by vacuum lamination in a stationary state (vacuum lamination method) or a roll-to-roll method.

In the solar cell module, the filler sheet is a layer for protecting the solar cell element in which the solar cell absorbs sunlight and generates electric power, and also maintains the performance and strength of the solar cell element and the solar cell module. And a layer for adhering a transparent protective material for maintaining durability and a back surface protective material. For this reason, the said filler sheet | seat needs the adhesiveness with a solar cell element, a transparent protective material, and a back surface protective material, durability, heat resistance, etc. of filler material itself. In addition, there is a need for a laminate characteristic that can produce a solar cell module by suitably sealing a solar cell element without generating wrinkles or the like in the manufacturing process of the vacuum laminating method or roll-to-roll method.

Conventionally, ethylene-vinyl acetate resin (EVA) has been used as such a filler sheet (Patent Document 1). EVA can also exhibit excellent heat resistance (especially, so-called heat-resistant creep resistance that does not cause displacement when stress is applied while heating) by crosslinking in the step of sealing the solar cell element. Moreover, the adhesiveness with a solar cell element, a transparent protective material, and a back surface protective material improves more by mix | blending coupling agents, such as a silane coupling agent.

On the other hand, sunlight is mixed light in a wavelength range of about 300 to 3000 nm, but light of all wavelengths is not necessarily used in the solar cell module.
In particular, the utilization factor of the light in the short wavelength region is low, and by continuously applying the light in the short wavelength region to the solar cell module, the filler sheet is discolored to reduce the power generation efficiency of the solar cell module, It is known to change color, and it is common to use a UV absorber so that light in the short wavelength region does not reach the member directly.

On the other hand, as one method for improving the power generation efficiency of the solar cell module, an attempt is made to convert light in a short wavelength region into light having a wavelength that can be used by the solar cell module.
For example, Patent Document 2 discloses a wavelength conversion film in which inorganic fine particles using an expensive rare metal such as Eu as a phosphor as a wavelength conversion material are dispersed in a transparent polymer. Patent Document 3 discloses the use of an inexpensive organic material-based phosphor. Furthermore, Patent Document 4 reports that practical wavelength conversion efficiency is obtained at a low concentration while using an organic material-based phosphor.
However, the addition of a wavelength conversion material to the filler sheet to impart wavelength conversion performance to the filler sheet has not been studied so far.

JP 7-297439 A JP 2004-134805 A Japanese Patent Laid-Open No. 10-261811 WO2013 / 054818

An object of this invention is to provide the solar cell module filler sheet which has high heat resistance, especially heat-resistant creep property, and also has wavelength conversion performance. Moreover, an object of this invention is to provide the solar cell module produced using this filler sheet for solar cell modules.

The present invention is a solar cell module filler sheet having three or more layers, wherein the three or more layers include at least outermost layers and wavelength conversion layers on both sides, and the outermost layer comprises ethylene-acetic acid. Contains a vinyl copolymer, an organic peroxide, and a radical-reactive silane coupling agent, and the wavelength conversion layer combines an ethylene-vinyl acetate copolymer and a light-emitting molecule and a self-aggregating molecule. It is a filler sheet for solar cell modules containing the light-emitting body which was made.
The present invention is described in detail below.

The present inventors have disclosed a solar cell module comprising an ethylene-vinyl acetate copolymer, an organic peroxide as a crosslinking agent for imparting heat resistance (particularly heat creep resistance), and a radical reactive silane coupling agent. It was studied that a wavelength conversion material (light emitting body) was added to a filler sheet for use (hereinafter also simply referred to as “filler sheet”) to impart wavelength conversion performance.
However, when the present invention uses an organic material-based luminescent material having a structure in which a luminescent molecule and a self-aggregating molecule are combined, the organic peroxide reacts with the luminescent material. As a result, it was found that the function of the light emitter is lost and it is difficult to obtain high wavelength conversion efficiency.
On the other hand, the present inventors incorporated a filler sheet into a multilayer structure of three or more layers and blended an organic peroxide and a radical-reactive silane coupling agent in the outermost layers on both sides, while containing a light emitter. It was found that by providing a conversion layer separately, a filler sheet having high heat resistance, particularly high heat creep resistance, and also having wavelength conversion performance was obtained, and the present invention was completed.

The filler sheet of the present invention has three or more layers. The three or more layers include at least outermost layers and wavelength conversion layers on both sides.
The longitudinal cross-sectional schematic diagram which showed an example of the filler sheet | seat of this invention is shown in FIG. A filler sheet A shown in FIG. 1 has outermost layers 2 and wavelength conversion layers 1 on both sides. In addition, although the filler sheet A shown in FIG. 1 has a three-layer structure, the filler sheet of the present invention may include other layers as long as it includes at least the outermost layer and the wavelength conversion layer on both sides. Good.

The outermost layer is a layer on both sides located on the outermost side among the three or more layers. The outermost layer contains an ethylene-vinyl acetate copolymer, an organic peroxide, and a radical reactive silane coupling agent.
The ethylene-vinyl acetate copolymer is obtained by copolymerizing ethylene, vinyl acetate, and a copolymerizable monomer that can be copolymerized with ethylene, if necessary. If it is a vinyl acetate copolymer, it will not specifically limit. The copolymerizable monomer is not particularly limited, and examples thereof include (meth) acrylic acid, (meth) acrylic acid ester, maleic acid, maleic anhydride, maleic acid ester and the like. These copolymerizable monomers may be used alone or in combination of two or more.

The amount of vinyl acetate in the ethylene-vinyl acetate copolymer is preferably 5 to 50% by weight. When the amount of vinyl acetate is less than 5% by weight, the transparency of the filler sheet may be lowered, and the power generation efficiency of the solar cell module may be lowered. If the amount of vinyl acetate exceeds 50% by weight, it may be difficult to form a filler sheet, or the mechanical strength may be lowered.

The melt flow rate of the ethylene-vinyl acetate copolymer is preferably 10 to 100 g / 10 min. When the melt flow rate is less than 10 g / 10 min, shear heat generation during molding of the ethylene-vinyl acetate copolymer is increased, which may cause gelation. When the melt flow rate exceeds 100 g / 10 min, the ethylene-vinyl acetate copolymer is not sufficiently crosslinked, the heat resistance of the filler sheet may be lowered, and the solar cell element is sealed. This may cause protrusion of the filler in the process.
The melt flow rate of the ethylene-vinyl acetate copolymer is a value measured according to JIS K7210: 1999.

In each of the outermost layers, the ethylene-vinyl acetate copolymer may or may not be the same.

The organic peroxide is a cross-linking agent for the ethylene-vinyl acetate copolymer, and is decomposed by heating in the step of sealing the solar cell element to cross-link the ethylene-vinyl acetate copolymer. Thereby, the filler sheet of the present invention is excellent in heat resistance, in particular, heat creep resistance.
The organic peroxide is not particularly limited as long as it is an organic peroxide usually used for a filler sheet. For example, di (2-t-butylperoxyisopropyl) benzene, dicumyl peroxide, di-t- Hexyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide, di-t-butyl peroxide, p-menthane hydroperoxide, 2,5- Dimethyl-2,5-di (t-butylperoxy) hexyne-3, 1,1-di (t-butylperoxy) -2-methylcyclohexane, 1,1-di (t-hexylperoxy) -3 , 3,5-trimethylcyclohexane, 1,1-di (t-hexylperoxy) cyclohexane, 1,1-di (t-butylperoxy) cyclohexane, , 2-di (4,4-di- (t-butylperoxy) cyclohexyl) propane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5 -Trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di- (3-methylbenzoylperoxy) hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate, 2,2-di (t-butylperoxy) ) Butane, t-butyl peroxybenzoate, n-butyl-4,4-di- (t Butylperoxy) valerate, and the like. These organic peroxides may be used alone or in combination of two or more. In each of the outermost layers, the organic peroxide may or may not be the same.

With respect to the content of the organic peroxide, a preferable lower limit with respect to 100 parts by weight of the ethylene-vinyl acetate copolymer in the outermost layer is 0.05 part by weight, and a preferable upper limit is 3 parts by weight. When the content is less than 0.05 parts by weight, the ethylene-vinyl acetate copolymer is not sufficiently crosslinked, and the heat resistance of the filler sheet may be lowered. When the content exceeds 3 parts by weight, a large amount of low molecular weight compounds such as acetone and carbon dioxide are generated along with the decomposition of the organic peroxide, and bubble expansion occurs at the interface with the transparent protective material and the solar cell element. And adhesion may be reduced. A more preferable lower limit of the content is 0.2 parts by weight, and a more preferable upper limit is 1 part by weight.

By blending the radical-reactive silane coupling agent in the outermost layer, the filler sheet of the present invention is excellent in adhesiveness with a transparent protective material and a solar cell element.
The radical-reactive silane coupling agent is not particularly limited. For example, a silane having an organic functional group such as a vinyl group, a methacryloxy group, or a mercapto group, and a substituent having reactivity with an inorganic substance such as a methoxy group or an ethoxy group. Compounds. Examples of the radical reactive silane coupling agent include vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane. Of these, 3-methacryloxypropyltrimethoxysilane is preferable. In each of the outermost layers, the radical reactive silane coupling agent may or may not be the same.

The content of the radical reactive silane coupling agent is preferably 0.05 parts by weight and preferably 3 parts by weight with respect to 100 parts by weight of the ethylene-vinyl acetate copolymer in the outermost layer. When the content is less than 0.05 parts by weight, the adhesiveness of the filler sheet to the transparent protective material and the solar cell element may be lowered. When the content exceeds 3 parts by weight, the cross-linking reaction of the ethylene-ethyl acetate copolymer may be hindered, and the heat resistance of the filler sheet may be lowered. May adversely affect transparency. The more preferable lower limit of the content is 0.07 parts by weight, and the more preferable upper limit is 1 part by weight.

The outermost layer may further contain other additives as long as the physical properties thereof are not impaired. Examples of the other additives include UV stabilizers, plasticizers, fillers, colorants, pigments, antioxidants, antistatic agents, surfactants, toning liquids, refractive index matching additives, and dispersion aids. Agents and the like.

The wavelength conversion layer contains an ethylene-vinyl acetate copolymer and a luminescent material in which a luminescent molecule and a self-aggregating molecule are bonded.
When the phosphor is present in a single layer with the organic peroxide, the organic peroxide reacts with the phosphor to lose the function of the phosphor, resulting in high wavelength conversion. It is difficult to get efficiency. In contrast, the inventors of the present invention have a multilayer structure of three or more layers as a filler sheet, and an organic peroxide and a radical-reactive silane coupling agent are blended in the outermost layers on both sides, while containing the light emitter. It has been found that by providing a wavelength conversion layer separately, a filler sheet having high heat resistance, particularly heat resistance creep resistance, and also having wavelength conversion performance can be obtained.
In this specification, wavelength conversion means down-conversion type wavelength conversion that absorbs light in a specific wavelength range and emits light in a longer wavelength range, thereby converting absorbed light to the longer wavelength side.

Examples of the ethylene-vinyl acetate copolymer include those similar to the ethylene-vinyl acetate copolymer in the outermost layer. Even if the ethylene-vinyl acetate copolymer is the same as the ethylene-vinyl acetate copolymer in the outermost layer, It does not have to be the same.

Examples of the luminescent molecule include a fluorescent molecule that absorbs light in a specific wavelength range and emits fluorescence in a longer wavelength range, and a phosphorescent molecule that emits phosphorescence. Those having a functional group capable of bonding (amino group, aldehyde group, carbonyl group, hydroxyl group, etc.) are preferred. The above-mentioned luminescent molecule has a larger Stokes shift, which is the difference between the excitation maximum wavelength and the emission maximum wavelength than the monomer due to the formation of a fluorescent molecule, particularly an excimer (exciton dimer), and has a quantum yield. It is preferably a fluorescent molecule that emits high fluorescence.
Examples of such molecules include pyrene derivatives, anthracene derivatives, naphthalene derivatives, fluorene derivatives, perylene derivatives, coronene derivatives, phenanthrene derivatives, fluoranthene derivatives, carbazole derivatives, chrysene derivatives, triphenylene derivatives, tetracene derivatives, pentacene derivatives, fluorenone derivatives, azulene. Derivatives, oligophenylene vinylene derivatives, oligophenylene ethynylene derivatives, porphyrin derivatives, cyanine dye derivatives and the like. These fluorescent molecules may be used alone or in combination of two or more.

Of these, a pyrene derivative or an anthracene derivative is preferable. In solar cell modules, ultraviolet absorbers are often used for the surface layer to prevent deterioration of the filler sheet used therein, and ultraviolet rays are not effectively used. The pyrene derivative or the anthracene derivative has an absorption wavelength in the ultraviolet region, and an excimer fluorescence wavelength is about 400 to 550 nm for the pyrene derivative and about 450 to 600 nm for the anthracene derivative, so that deterioration of the filler material is difficult to occur. Since it exists in the absorption wavelength range of the solar cell element used for a solar cell module, it is suitable. Furthermore, the use of an ultraviolet light absorber can be expected to be reduced by using the pyrene derivative or the anthracene derivative.

Examples of the pyrene derivatives include pyrenecarboxylic acid, pyrenedicarboxylic acid, pyrenebutanoic acid, methylpyrenecarboxylic acid, methoxypyrenebutanoic acid, pyrenecarbaldehyde, pyreneamine, pyreneamine, nitropyreneamine, pyreneol, pyrenediol, and phenylenepyrene. be able to. More specifically, 1-pyrenecarboxylic acid, 1,6-pyrene dicarboxylic acid, 1-pyrenebutanoic acid, 6-methylpyrene-1-carboxylic acid, 6-methoxypyrene-1-butanoic acid, pyrene-1-carbaldehyde Pyrene-1-amine, pyren-2-amine, pyrene-1,6-diamine, 6-nitropyren-1-amine, pyren-1-ol, pyrene-1,6-diol, 2-phenylpyrene, 6- Although propylpyrene-1-propionic acid can be mentioned, it is not limited to these. These pyrene derivatives may be used alone or in combination of two or more. Of these, 1-pyrenebutanoic acid and pyren-1-amine are preferable.

Examples of the anthracene derivative include phenyleneanthraceneamine, diphenylanthraceneamine, (hydroxyphenyl) anthracene, (carboxyphenyl) anthracene, pyridylanthracene, naphthylanthracene, (hydroxynaphthyl) anthracene, (aminonaphthyl) anthracene, anthryloxyacetic acid, bis Mention may be made of (dihydroxyphenyl) anthracene. More specifically, the anthracene derivatives include 9- (4-hydroxyphenyl) anthracene, 9- (4-aminophenyl) anthracene, 9,10-diphenylanthracen-1-amine, 9- (4-carboxyphenyl). ) Anthracene, 9- (4-pyridyl) anthracene, 9- (1-naphthyl) anthracene, 9- (1-hydroxy-4-naphthyl) anthracene, 9- (1-amino-4-naphthyl) anthracene, 4- ( Examples include, but are not limited to, 9-anthryl) phenoxyacetic acid and 9,10-bis (3,5-dihydroxyphenyl) anthracene. These anthracene derivatives may be used alone or in combination of two or more. Of these, 9- (4-hydroxyphenyl) anthracene, 9- (4-aminophenyl) anthracene, and 9,10-diphenylanthracen-1-amine are preferable.

Examples of the phosphorescent molecule include complex compounds that contain any one metal belonging to Group 8, 9 or 10 of the periodic table and exhibit phosphorescence, such as iridium complexes. , Organometallic complexes that exhibit phosphorescence, such as osmium complexes and rare earth complexes.
Examples of the organic compound serving as a ligand for such an organometallic complex include carbazole derivatives, bipyridine derivatives, rosalin derivatives, anthracene derivatives, phthalocyanine derivatives, and the like.
In addition to the complex compound, an eosin derivative, a chlorophyll derivative, a β-carotene derivative, a cyclic azine derivative, a stilbene derivative, a triphenylene derivative, or the like may be used as the phosphorescent molecule.

The “self-assembling molecule” is a molecule that has a function of assembling in a self-organizing manner, and in this specification, means a molecule that can self-assemble in the ethylene-vinyl acetate copolymer. . In the present specification, the “self-assembling molecule” forms an aggregate in a solution containing not only the solvent but also the ethylene-vinyl acetate copolymer, and even when solidified by distilling off the solvent, The aggregate is maintained in the solid. Furthermore, even a molecule that does not form an aggregate in a solution or melt containing the ethylene-vinyl acetate copolymer is formed into a film (solidified) by evaporating the solvent or the like to form a film. Molecules that can be assembled and oriented in a self-assembled manner in the ethylene-vinyl acetate copolymer also correspond to “self-assembling molecules” in this specification.
When the self-assembling molecules are assembled in a self-organized manner, the light-emitting molecules (particularly fluorescent molecules) bound to the self-assembling molecules are different in the difference between the excitation maximum wavelength and the emission maximum wavelength than the monomer. An excimer (exciton dimer) that emits light (particularly fluorescence) having a large Stokes shift and a high quantum yield can be formed. Thus, high wavelength conversion efficiency can be obtained because the light emitters are associated.

The self-assembling molecule has a site (for example, amide bond, ester bond, urethane bond, urea bond) that promotes association in the ethylene-vinyl acetate copolymer and imparts appropriate dispersibility. It is preferably a molecule having a hydrocarbon moiety for the purpose. As for the said hydrocarbon site | part, a C3-C40 linear alkyl group, a branched alkyl group, and a cyclic alkyl group are mentioned, for example. In addition, the said hydrocarbon site | part may contain the hetero atom (oxygen, nitrogen, sulfur) in the range which can ensure the affinity with the said ethylene-vinyl acetate copolymer.

Examples of the self-assembling molecule include amino acid derivatives, polycyclic aromatic derivatives, cholesterol derivatives, and sugar derivatives. Preferred examples include glutamic acid dialkylamide, aspartic acid dialkyl ester, lysine dialkylamide, acylglucosamine, and alkyl. Examples thereof include oxyazobenzene and dialkoxyanthracene. Preferable specific examples include didodecylated glutamide, dibutylated glutamide, and didodecylated lysine. These self-assembling molecules may be used alone or in combination of two or more.

The light emitter is a combination of the light emitting molecule and the self-assembling molecule.
Any method may be used for producing the phosphor in which the luminescent molecule and the self-assembling molecule are bonded. For example, the functional group of each of the luminescent molecule and the self-assembling molecule is contained in an appropriate solvent. The method of reacting and bonding is mentioned.

The luminous body may be associated and oriented in the ethylene-vinyl acetate copolymer to form a fibrous aggregate. The average length of such a fibrous aggregate is preferably 170 nm or more, and more preferably 200 nm or more. The average aspect ratio, which is the ratio of thickness to length, is preferably 10 or more.
The fibrous aggregate is an oriented aggregate formed by associating and aligning the luminous body with high efficiency in the ethylene-vinyl acetate copolymer. By forming such a fibrous aggregate, the wavelength conversion efficiency is improved because the structure is more suitable for wavelength conversion than the monomer of the light-emitting molecule (especially fluorescent molecule) and even excimer. To do.
In general, the fibrous aggregate is observed with a transmission electron microscope. The average length of the fibrous aggregate is obtained by measuring the length of 100 fibrous aggregates in a transmission electron micrograph and taking the arithmetic average. Similarly, the average of the aspect ratios of the fibrous aggregates is obtained by measuring the average thickness of the fibrous aggregates in the transmission electron micrograph and dividing the average length by the average thickness.

The method for forming the fibrous aggregate is not particularly limited, but a method in which the phosphor is dispersed and reassembled in the ethylene-vinyl acetate copolymer is preferable. Specifically, for example, a precursor sheet once formed by a conventionally known method is treated by heat curing at a temperature equal to or higher than the softening point of the ethylene-vinyl acetate copolymer, and the ethylene-vinyl acetate copolymer is used. Examples thereof include a method in which the precursor sheet is swollen with a solvent that swells and disperses the phosphor without changing the form of the polymer, is allowed to stand for a certain period of time, and is dried.

When the luminescent molecule is the fluorescent molecule, the content of the luminescent material is preferably 0.0001 parts by weight with respect to 100 parts by weight of the ethylene-vinyl acetate copolymer in the wavelength conversion layer, and 10 is preferably the upper limit. Parts by weight. When the content of the light emitter is less than 0.0001 part by weight, the wavelength conversion efficiency of the filler sheet may be lowered. When the content of the phosphor exceeds 10 parts by weight, the transparency of the filler sheet may be lowered, or the properties of the ethylene-vinyl acetate copolymer may be changed.

As described above, when the wavelength conversion layer contains the organic peroxide, since the function of the light emitter is lost by reacting with the light emitter, the wavelength conversion layer may not contain the organic peroxide. preferable. However, the wavelength conversion layer is a small amount, for example, 0.01 to 0.1 with respect to 100 parts by weight of the ethylene-vinyl acetate copolymer in the wavelength conversion layer as long as sufficient wavelength conversion efficiency is obtained. If it is about a weight part, you may contain the said organic peroxide.
The wavelength conversion layer may contain the radical reactive silane coupling agent.

The wavelength conversion layer may further contain the same additive as the other additive in the outermost layer within a range not impairing its physical properties.

The thickness of the wavelength conversion layer is preferably 10 to 33% with respect to the thickness of the entire filler sheet. When the thickness of the wavelength conversion layer is less than 10%, the wavelength conversion efficiency of the filler sheet may be lowered. If the thickness of the wavelength conversion layer exceeds 33%, the thickness of the non-crosslinked wavelength conversion layer increases, and the heat resistance of the filler sheet, particularly the heat resistance creep resistance, may decrease. Moreover, since the thickness of the said outermost layer reduces, the adhesiveness with respect to the transparent protective material and solar cell element of a filler sheet may fall.

The filler sheet of the present invention has a preferable lower limit of thickness of 200 μm and a preferable upper limit of 1000 μm. When the thickness is less than 200 μm, the filler sheet cannot sufficiently follow the solar cell element in the step of sealing the solar cell element, so that voids are likely to be generated, and the load on the solar cell element due to the pressure is increased. For this reason, there is a risk of insufficient adhesion and durability and a decrease in power generation performance. When the thickness exceeds 1000 μm, the filler may protrude and contaminate the device in the step of sealing the solar cell element. The more preferable lower limit of the thickness is 150 μm, and the more preferable upper limit is 700 μm.

As a method for producing the filler sheet of the present invention, the ethylene-vinyl acetate copolymer, the organic peroxide, the radical reactive silane coupling agent, the phosphor, and an additive to be blended as necessary. Examples include a method in which a multilayer T-die extruder is supplied at a predetermined weight ratio, melted and kneaded, and extruded from the multilayer T-die extruder into a multilayer sheet. In addition, the fibrous aggregates of the luminous body are formed on the obtained sheet by a method such as a treatment by heat curing at a temperature higher than the softening point of the ethylene-vinyl acetate copolymer as described above. May be.

Using the filler sheet of the present invention, a solar cell element can be sealed to produce a solar cell module.
The solar cell element is generally composed of a photoelectric conversion layer in which electrons are generated by receiving light, an electrode layer for taking out the generated electrons, and a glass substrate.

Examples of the photoelectric conversion layer include crystal semiconductors such as single crystal silicon, single crystal germanium, polycrystalline silicon, and microcrystalline silicon, amorphous semiconductors such as amorphous silicon, GaAs, InP, AlGaAs, Cds, CdTe, and Cu _2. Examples thereof include compounds formed from compound semiconductors such as S, CuInSe ₂ and CuInS ₂ , and organic semiconductors such as phthalocyanine and polyacetylene.
The photoelectric conversion layer may be a single layer or a multilayer.
The thickness of the photoelectric conversion layer is preferably 0.1 to 200 μm.

The glass substrate may be a glass substrate that can withstand the process of laminating the photoelectric conversion layer and the electrode material, and does not contain a substance that contaminates the photoelectric conversion layer when used as a solar cell. If it does not specifically limit, For example, soda-lime glass etc. are mentioned.
The thickness of the glass substrate is preferably 0.1 to 3 mm.

The electrode layer is a layer made of an electrode material.
The electrode layer may be on the photoelectric conversion layer, between the photoelectric conversion layer and the glass substrate, or on the glass substrate surface as necessary.
Further, the solar cell element may have a plurality of the electrode layers.
Since the electrode layer on the light receiving surface side (surface) needs to be transparent, the electrode material is preferably a general transparent electrode material such as a metal oxide. Although it does not specifically limit as said transparent electrode material, ITO or ZnO etc. are used suitably.
When the transparent electrode is not used, the bus electrode or the finger electrode attached thereto may be patterned with a metal such as silver.
The electrode layer on the back side (back side) does not need to be transparent and may be made of a general electrode material, but silver is preferably used as the electrode material.

The method for producing the solar cell element is not particularly limited as long as it is a known method. For example, a method for producing a pn junction surface on a silicon wafer and printing the electrode after baking, It can be formed by a known method such as a method of arranging a photoelectric conversion layer or an electrode layer.

Examples of a method for sealing a solar cell element using the filler sheet of the present invention include a transparent protective material, a filler sheet of the present invention, a solar cell element, a filler sheet of the present invention, and a back surface protective material. The laminate obtained by laminating the layers in this order is heated in a stationary state under reduced pressure while applying a pressing force in the thickness direction, and the pressure-sensitive adhesive sheet of the present invention is pressure-bonded to the solar cell element (vacuum) Laminating method). Especially, it is preferable to install the filler sheet of this invention between a transparent protective material and the light-receiving surface side of the photoelectric converting layer of a solar cell element. A solar cell module produced by sealing a solar cell element between a transparent protective material and a back surface protective material using the filler sheet of the present invention, wherein the transparent protective material and the solar cell element The solar cell module in which the filler sheet of the present invention is installed between the light receiving surface side of the photoelectric conversion layer is also one aspect of the present invention. In addition, while a transparent protective material is laminated | stacked on the light-receiving surface side of a photoelectric converting layer, the aspect which does not laminate | stack a back surface protective material on the back surface side is also mentioned.
The step of heating the laminate while applying a pressing force in the thickness direction under reduced pressure can be performed using a conventionally known apparatus such as a vacuum laminator.
As the solar cell element and the filler sheet of the present invention, a rectangular sheet adjusted to a desired size in advance may be used.

The step of heating the laminate while applying a pressing force in the thickness direction under reduced pressure is preferably performed in a reduced pressure atmosphere of 1000 Pa or less, and more preferably in a reduced pressure atmosphere of 80 to 1000 Pa.
In the heating step, the laminate is preferably heated to 100 to 170 ° C, more preferably 120 to 160 ° C. The heating time is preferably 1 to 15 minutes, more preferably 2 to 10 minutes.

The said transparent protective material is a layer which can become the outermost layer by the side of the light-receiving surface of the photoelectric converting layer of a solar cell module.
It is preferable that the said transparent protective material consists of glass at the point which is excellent in transparency, heat resistance, and a flame retardance.
When the said transparent protective material consists of glass, it is preferable that the thickness of the said transparent protective material is 0.1-5 mm, and it is more preferable that it is 1.0-3.5 mm.

The back surface protective material is a layer that can be the outermost layer on the back surface side of the solar cell module (that is, the side opposite to the light receiving surface of the photoelectric conversion layer).
The said back surface protection material may consist of resin sheets, such as glass, stainless steel, a polyvinyl fluoride / polyester / polyvinyl fluoride laminated sheet, a polyester / aluminum / polyester laminated sheet, in the point which is excellent in water vapor | steam barrier property and a weather resistance. preferable. In addition, the said back surface protection material does not need to be especially transparent.

When the said back surface protection material consists of glass or stainless steel, it is preferable that the thickness of the said back surface protection material is 0.1-5 mm, and it is more preferable that it is 1.0-3.5 mm.
When the said back surface protection material consists of laminated sheets, it is preferable that the thickness of the said back surface protection material is 10-500 micrometers, and it is more preferable that it is 100-300 micrometers.

The transparent protective material preferably has an embossed shape on the outermost surface. By having the said emboss shape, the reflection loss of sunlight can be reduced, glare can be prevented, and an external appearance can be improved.
The embossed shape may be a regular uneven shape or a random uneven shape.
The embossed shape is a step of embossing before the transparent protective material is bonded to the solar cell element, embossing after bonding to the solar cell element, or bonding with the solar cell element. You may mold at the same time.

According to the present invention, it is possible to provide a solar cell module filler sheet having high heat resistance, particularly heat creep resistance, and also having wavelength conversion performance. Moreover, according to this invention, the solar cell module produced using this solar cell module filler sheet can be provided.

It is the longitudinal cross-sectional schematic diagram which showed an example of the filler sheet | seat of this invention.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples.

(Synthesis of phosphor-1)
1-pyrenebutanoic acid is dissolved in THF as a luminescent molecule (20 mM), 1.05 molar equivalent of didodecylated L-glutamide is added as a self-assembling molecule, and 1.25 molar equivalent of triethylamine and cyanophosphoric acid are stirred in an ice bath. 2 molar equivalents of diethyl were added. After stirring for 12 hours at room temperature to allow the reaction to proceed, the solvent was removed and recrystallization was performed from methanol to obtain phosphor-1.

(Synthesis of phosphor-2)
Phosphor-2 was obtained in the same manner as the synthesis of phosphor-1, except that the luminescent molecule was 9,10-diphenylanthracen-1-amine.

Example 1
100 parts by weight of ethylene-vinyl acetate copolymer (vinyl acetate content: 28% by weight, melt flow rate: 20 g / 10 min), t-butyl peroxy-2-ethylhexyl monocarbonate as organic peroxide 0.8% by weight Part, 0.5 part by weight of 3-methacryloxypropyltrimethoxysilane as a radical reactive silane coupling agent, 0.3 part by weight of triallyl isocyanurate as a crosslinking aid, and 0.2 part by weight of a hindered amine light stabilizer The resin composition for outermost layer containing was supplied to each of two extruders.
A wavelength conversion layer containing 100 parts by weight of an ethylene-vinyl acetate copolymer (vinyl acetate content: 28% by weight, melt flow rate: 20 g / 10 min) and 0.5 parts by weight of the phosphor-1 obtained above. The resin composition was supplied to the remaining one extruder.
After melt-kneading at 120 ° C., the three extruders are supplied to one feed block, and the wavelength conversion layer containing phosphor-1 is extruded as an intermediate layer from a T-die disposed at the tip of the feed block, A filler sheet having a thickness of 0.5 mm was obtained. The thickness ratio of the outermost layer, the wavelength conversion layer (intermediate), and the outermost layer in the filler sheet was adjusted to 40:20:40.

(Example 2)
A filler sheet was obtained in the same manner as in Example 1 except that the phosphor was changed to that shown in Table 1.

(Comparative Example 1)
100 parts by weight of ethylene-vinyl acetate copolymer (vinyl acetate content: 28% by weight, melt flow rate: 20 g / 10 min), t-butyl peroxy-2-ethylhexyl monocarbonate as organic peroxide 0.8% by weight Part, 0.5 part by weight of 3-methacryloxypropyltrimethoxysilane as a radical reactive silane coupling agent, 0.3 part by weight of triallyl isocyanurate as a crosslinking aid, 0.2 part by weight of a hindered amine light stabilizer, and The resin composition containing 0.5 parts by weight of the phosphor-1 obtained above was supplied to an extruder, melted and kneaded at 120 ° C., and then extruded from a T die to obtain a single thickness of 0.5 mm. A filler sheet consisting of layers was obtained.

(Comparative Example 2)
Resin composition containing 100 parts by weight of ethylene-vinyl acetate copolymer (vinyl acetate content: 28% by weight, melt flow rate: 20 g / 10 min) and 0.5 parts by weight of phosphor-1 obtained above The product was supplied to an extruder, melted and kneaded at 120 ° C., and then extruded from a T-die to obtain a filler sheet consisting of a single layer having a thickness of 0.5 mm.

(Evaluation)
The following evaluation was performed about the filler sheet | seat obtained by the Example and the comparative example. The results are shown in Table 1.

(1) Evaluation of wavelength conversion performance The phosphors used (phosphor-1 and phosphor-2) were dissolved in toluene so as to be 0.25 mol / L to obtain a measurement sample. Using a fluorescence measuring instrument (F-2700 type spectrofluorometer manufactured by Hitachi High-Technologies Corporation), the fluorescence wavelength at the excitation wavelength of 350 nm of the measurement sample was measured at 100 ° C., and the wavelength giving the maximum sensitivity (λmax1 ) The measurement sample was cooled to 0 ° C., and the fluorescence wavelength at the excitation wavelength of 350 nm of the measurement sample was measured in the same manner to obtain the wavelength (λmax2) that gave the maximum sensitivity. Note that λmax1 is the fluorescence wavelength of the phosphor in an unassociated monomer state, and λmax2 is the fluorescence wavelength of the phosphor in a completely associated state.
The phosphors used (Phosphor-1 and Phosphor-2) have a fluorescence wavelength (λmax1) in a monomer state that is not in the absorption wavelength region of the solar cell element, but fluorescence in a fully associated state. The wavelength (λmax2) is in the absorption wavelength region of the solar cell element. Therefore, when the fluorescence intensity Em (λ) at the fluorescence wavelength λ is measured for the filler sheet, the wavelength conversion performance is higher as Em (λmax2) / Em (λmax1) is larger, which contributes to the improvement of the power generation efficiency of the solar cell module. It can be judged that it is possible.

Next, a reinforced glass having a thickness of 3.2 mm, a release polyester sheet, an obtained filler sheet, a release polyester sheet, and a protective group so as to have the same pressing conditions as in the step of sealing the solar cell element The materials were laminated in this order, and this was pressed using a vacuum laminator (trade name “PVL1222S” manufactured by Nisshinbo Mechatronics, Inc.) under the conditions of 150 ° C., evacuation for 5 minutes, and pressurization time of 15 minutes, It peeled and the filler sheet was obtained.
Using a fluorometer (F-2700 type spectrofluorophotometer manufactured by Hitachi High-Technologies Corporation), Em (λmax1) and Em (λmax2) at an excitation wavelength of 350 nm of the obtained filler sheet were measured, and the following The wavelength conversion performance was evaluated on the basis.
：: Em (λmax2) / Em (λmax1) is 1.5 or more ○: Em (λmax2) / Em (λmax1) is 1 or more and less than 1.5 Δ: Em (λmax2) / Em (λmax1) is 0.5 Above, less than 1 x: Em (λmax2) / Em (λmax1) is less than 0.5

(2) Evaluation of heat resistance (heat-resistant creep resistance) The obtained filler sheet was cut into a size of 2 cm × 2 cm. Tempered glass 1 (AGC Fabrictech, white plate-type heat-treated glass), filler sheet, and tempered glass 2 (AGC Fabrictech, white plate, 4 mm, 10 cm × 10 cm), 4 mm thick and 5 cm × 5 cm thick The template heat treatment glass) is laminated in this order, and this is heated and degassed at 150 ° C. for 300 seconds using a vacuum laminator (trade name “PVL1222S”, manufactured by Nisshinbo Mechatronics), and then at 150 ° C. for 900 seconds. The laminated body was produced by pressing at the above.
The position of the tempered glass 1 in the obtained laminate was marked on the tempered glass 2 with a magic, and then placed vertically in an oven at 120 ° C. 24 hours after installation, the displacement of the position of the tempered glass 1 was measured, and the heat resistance was evaluated according to the following criteria.
A: The deviation was less than 0.5 mm.
Δ: The deviation was 0.5 mm or more and less than 2 mm.
X: The deviation was 2 mm or more.

According to the present invention, it is possible to provide a solar cell module filler sheet having high heat resistance, particularly heat creep resistance, and also having wavelength conversion performance. Moreover, according to this invention, the solar cell module produced using this solar cell module filler sheet can be provided.

A Filler sheet 1 Wavelength conversion layer 2 Outermost layer

Claims (3)

A solar cell module filler sheet having three or more layers,
The three or more layers include at least outermost layers and wavelength conversion layers on both sides,
The outermost layer contains an ethylene-vinyl acetate copolymer, an organic peroxide, and a radical reactive silane coupling agent,
The wavelength conversion layer contains an ethylene-vinyl acetate copolymer, and a light emitting body in which a light emitting molecule and a self-aggregating molecule are bonded to each other. The luminescent molecule in the luminescent material is a pyrene derivative or an anthracene derivative, and the solar cell module filler sheet according to claim 1. A solar cell module produced by sealing a solar cell element between a transparent protective material and a back surface protective material, using the solar cell module filler sheet according to claim 1 or 2,
A solar cell module, wherein the solar cell module filler sheet according to claim 1 or 2 is installed between the transparent protective material and a light receiving surface side of the photoelectric conversion layer of the solar cell element.

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