JP2010021498A - Thin film solar cell, solar cell unit, and solar cell structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a practical solar cell which has superior durability to humidity. <P>SOLUTION: The solar cell includes a compound semiconductor-based solar cell element 6 which receives light rays to generate electric power, a gas barrier film 3 which covers the compound semiconductor-based solar cell element 6, and an ultraviolet-ray cutting film 2 which covers a light-receiving surface of the compound semiconductor-based solar cell element 6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thin film solar cell, a solar cell unit, and a solar cell structure.

  Conventionally, as a technique for protecting a solar cell, a technique for covering the solar cell with some film has been proposed. Examples of such a technique include the techniques described in Patent Document 1, Patent Document 2, and the like.

JP 2000-174297 A JP 2000-174298 A

However, the conventional techniques described in Patent Documents 1 and 2 are not sufficiently durable against humidity.
The present invention has been made in view of the above problems, and an object thereof is to provide a practical thin-film solar cell, a solar cell unit, and a solar cell structure excellent in durability against humidity.

  The inventors of the present invention have intensively studied in view of the above problems, and as a result, a thin-film solar cell, a solar cell element that generates power by receiving light, a gas barrier film that covers the solar cell element, and a light-receiving surface of the solar cell element It has been found that a practical thin film solar cell having durability against humidity can be realized by comprising an ultraviolet cut film for covering, and the present invention has been completed.

  That is, the gist of the present invention is characterized by comprising a solar cell element that generates light by receiving light, a gas barrier film that covers the solar cell element, and an ultraviolet cut film that covers a light receiving surface of the solar cell element. It exists in a thin film solar cell (Claim 1).

At this time, it is preferable to provide a getter material film that absorbs moisture and / or oxygen between the solar cell element and the gas barrier film.
It is also preferable to provide a weather-resistant protective film that covers the light-receiving surface of the solar cell element.
Furthermore, it is preferable to provide a sealing material for sealing the edge of the gas barrier film.
It is also preferable to provide a back sheet (claim 5).
Furthermore, the solar cell element is preferably a compound semiconductor solar cell element or an organic solar cell element.

Still another subject matter of the present invention lies in a solar cell unit comprising a base material and the thin-film solar cell of the present invention provided on the base material (claim 7).
Still another subject matter of the present invention lies in a solar cell structure comprising an article and the thin-film solar cell of the present invention provided on the article (claim 8).

  ADVANTAGE OF THE INVENTION According to this invention, the practical thin film solar cell excellent in durability with respect to humidity, a solar cell unit provided with the same, and a solar cell structure can be provided.

  Hereinafter, the present invention will be described in detail with reference to embodiments, examples, etc., but the present invention is not limited to the following embodiments, examples, etc., and can be arbitrarily set within the scope of the present invention. Can be changed and implemented.

  FIG. 1 is a cross-sectional view schematically showing the configuration of a thin film solar cell as one embodiment of the present invention. As shown in FIG. 1, the thin film solar cell 100 of this embodiment includes a weather-resistant protective film 1, an ultraviolet cut film 2, a gas barrier film 3, a getter material film 4, a sealing material 5, and a solar cell element. 6, a sealing material 7, a getter material film 8, a gas barrier film 9, and a back sheet 10 in this order, and further a sealing material 11 that seals the edges of the weatherproof protective film 1 and the back sheet 10. I have. And light is irradiated from the side (downward in the figure) where the weather-resistant protective film 1 was formed, and the solar cell element 6 generates electric power. In addition, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. .

[Weather-resistant protective film 1]
The weather-resistant protective film 1 is a film that protects the solar cell element 6 from weather changes.
Some components of the solar cell element 6 are deteriorated by temperature change, humidity change, natural light, erosion caused by wind and rain, and the like. Therefore, by covering the solar cell element 6 with the weather-resistant protective film 1, the solar cell element 6 and the like are protected from weather changes and the power generation capacity is kept high.

  Since the weather-resistant protective film 1 is located on the outermost layer of the thin-film solar cell 100, it is suitable as a surface coating material for the thin-film solar cell 100 such as weather resistance, heat resistance, transparency, water repellency, stain resistance, and mechanical strength. It is preferable that it has a good performance and has the property of maintaining it for a long period of time in outdoor exposure.

  Moreover, the weather-resistant protective film 1 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is preferably 80% or more, more preferably 90% or more, and particularly preferably 95%.

  Furthermore, since the thin film solar cell 100 is often heated by receiving light, it is preferable that the weather-resistant protective film 1 also has heat resistance. From this viewpoint, the melting point of the constituent material of the weather-resistant protective film 1 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower. Preferably it is 300 degrees C or less. By increasing the melting point, the possibility that the weather-resistant protective film 1 is melted and deteriorated when the thin-film solar cell 100 is used can be reduced.

The material which comprises the weather-resistant protective film 1 is arbitrary if it can protect the solar cell element 6 from a weather change. Examples of the material include polyethylene resin, polypropylene resin, cyclic polyolefin resin, AS (acrylonitrile-styrene) resin, ABS (acrylonitrile-butadiene-styrene) resin, polyvinyl chloride resin, fluorine resin, polyethylene terephthalate, polyethylene Examples thereof include polyester resins such as naphthalate, phenol resins, polyacrylic resins, polyamide resins such as various nylons, polyimide resins, polyamide-imide resins, polyurethane resins, cellulose resins, silicone resins, and polycarbonate resins.
Among them, fluorine resin is preferable, and specific examples thereof include polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy copolymer (PFA), 4-fluoroethylene-6-fluoride. Propylene copolymer (FEP), 2-ethylene-4-fluoroethylene copolymer (ETFE), poly-3-fluoroethylene chloride (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), etc. Can be mentioned.
In addition, the weather-resistant protective film 1 may be formed with 1 type of material, and may be formed with 2 or more types of materials. Moreover, although the weather-resistant protective film 1 may be formed with the single layer film, the laminated | multilayer film provided with the film of 2 or more layers may be sufficient as it.

  The thickness of the weather-resistant protective film 1 is not particularly specified, but is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility.

Moreover, you may perform surface treatment, such as a corona treatment and a plasma treatment, for the weather-resistant protective film 1 in order to improve adhesiveness with another film.
The weatherproof protective film 1 is preferably provided on the outer side as much as possible in the thin film solar cell 100. This is because more of the constituent members of the thin film solar cell 100 can be protected.

[UV cut film 2]
The ultraviolet cut film 2 is a film that prevents the transmission of ultraviolet rays.
Some components of the thin film solar cell 100 are deteriorated by ultraviolet rays. Some of the gas barrier films 3 and 9 are deteriorated by ultraviolet rays depending on the type. Therefore, the ultraviolet cut film 2 is provided in the light receiving portion of the thin film solar cell 100 and the ultraviolet cut film 2 covers the light receiving surface 6a of the solar cell element 6, so that the solar cell element 6 and, if necessary, the gas barrier films 3, 9 and the like. Can be protected from ultraviolet rays and the power generation capacity can be kept high.

  The degree of the ability to suppress the transmission of ultraviolet rays required for the ultraviolet cut film 2 is such that the transmittance of ultraviolet rays (for example, wavelength 300 nm) is preferably 50% or less, more preferably 30% or less, and particularly preferably. 10% or less.

  Further, the ultraviolet cut film 2 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is preferably 80% or more, more preferably 90% or more, and particularly preferably 95% or more.

  Furthermore, since the thin film solar cell 100 is often heated by receiving light, the ultraviolet cut film 2 preferably has heat resistance. From this viewpoint, the melting point of the constituent material of the ultraviolet cut film 2 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably. Is 300 ° C. or lower. If the melting point is too low, the ultraviolet cut film 2 may melt when the thin film solar cell 100 is used.

  Moreover, the ultraviolet cut film 2 has a high softness | flexibility, its adhesiveness with an adjacent film is favorable, and what can cut water vapor | steam and oxygen is preferable.

  The material which comprises the ultraviolet cut film 2 is arbitrary if the intensity | strength of an ultraviolet-ray can be weakened. Examples of the material include films formed by blending an ultraviolet absorber with an epoxy, acrylic, urethane, or ester resin. Further, a film in which a layer of an ultraviolet absorbent dispersed or dissolved in a resin (hereinafter referred to as “ultraviolet absorbing layer” as appropriate) is formed on a base film may be used.

  As the ultraviolet absorber, for example, a salicylic acid-based, benzophenone-based, benzotriazole-based, or cyanoacrylate-based one can be used. Of these, benzophenone and benzotriazole are preferable. Examples of this include various aromatic organic compounds such as benzophenone and benzotriazole.

  Examples of benzophenone-based UV absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2, 2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy-5- Benzophenone) methane and the like.

  Examples of benzotriazole ultraviolet absorbers include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole and 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole. 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5-methylphenyl) -5-chlorobenzo Triazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) ) Benzotriazole, 2- {2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-me Butylphenyl} benzotriazole, 2,2- methylenebis {4- (1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl) phenol}, and the like. In addition, a ultraviolet absorber may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  As described above, a film in which an ultraviolet absorbing layer is formed on a base film can be used as the ultraviolet absorbing film. Such a film can be produced, for example, by applying a coating solution containing an ultraviolet absorber on a substrate film and drying it.

Although the material of a base film is not specifically limited, For example, polyester is mentioned at the point from which the balance of heat resistance and a softness | flexibility is obtained.
Application | coating can be performed by arbitrary methods. Examples include reverse roll coating, gravure coating, kiss coating, roll brushing, spray coating, air knife coating, wire barber coating, pipe doctor method, impregnation / coating method, curtain coating method and the like. In addition, these methods may be performed alone or in any combination of two or more.

The solvent used in the coating solution is not particularly limited as long as it can uniformly dissolve or disperse the UV absorber. For example, a liquid resin can be used as a solvent, and examples thereof include polyester, acrylic, polyamide, polyurethane, polyolefin, polycarbonate, polystyrene, and other synthetic resins. It is done. Further, for example, natural polymers such as gelatin and cellulose derivatives; water, alcohol mixed solutions of water and ethanol, and the like can also be used as the solvent.
Further, an organic solvent may be used as the solvent. If an organic solvent is used, it becomes possible to dissolve or disperse the pigment and the resin, and to improve the coatability. Examples of the organic solvent include alcohols such as methanol and ethanol; glycols such as ethylene glycol and diethylene glycol; esters such as ethyl acetate, isopropyl acetate and n-butyl acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclohexane Examples thereof include ketones such as pentanone, isophorone and diacetone alcohol.
In addition, 1 type may be used for a solvent and it may use 2 or more types together by arbitrary combinations and a ratio.

The coating solution may further contain a surfactant. Use of the surfactant improves the dispersibility of the ultraviolet absorbing dye in the resin. Thereby, in an ultraviolet absorption layer, generation | occurrence | production of the dent by adhesion of foreign matters etc. by a micro bubble, the repelling in a drying process, etc. are suppressed.
Known surfactants (cationic surfactants, anionic surfactants, nonionic surfactants) can be used as the surfactant. Among these, a silicon-based surfactant or a fluorine-based surfactant is preferable. Specific examples thereof include silicon surfactants such as silane compounds such as aminosilane, acrylic silane, and vinylbenzyl silane; siloxane compounds such as polydimethylsiloxane and polyalkoxysiloxane. On the other hand, examples of the fluorine-based surfactant include tetrafluoroethylene; perfluoroalkyl compounds such as perfluoroalkylammonium salt and perfluoroalkylsulfonic acid amide. In addition, 1 type may be used for surfactant and it may use 2 or more types together by arbitrary combinations and a ratio.

  In addition, the drying after apply | coating a coating liquid to a base film can employ | adopt well-known drying methods, such as hot air drying and drying by an infrared heater, for example. Among these, hot air drying with a high drying speed is preferable.

Examples of specific products of the ultraviolet cut film 2 include Cut Ace (MKV Plastic Co., Ltd.).
The ultraviolet cut film 2 may be formed of one kind of material or may be formed of two or more kinds of materials. Further, the ultraviolet cut film 2 may be formed of a single layer film, but may be a laminated film including two or more layers.

  The thickness of the ultraviolet cut film 2 is not particularly defined, but is usually 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase the absorption of ultraviolet rays, and decreasing the thickness tends to increase the transmittance of visible light.

Although the ultraviolet cut film 2 should just be provided in the position which covers at least one part of the light-receiving surface 6a of the solar cell element 6, Preferably it is provided in the position which covers all the light-receiving surfaces 6a of the solar cell element 6. FIG.
However, the ultraviolet cut film 2 may be provided at a position other than the position covering the light receiving surface 6 a of the solar cell element 6.

[Gas barrier film 3]
The gas barrier film 3 is a film that prevents permeation of water and oxygen.
The solar cell element 6 tends to be vulnerable to moisture and oxygen. In particular, a transparent electrode such as ZnO: Al, a compound semiconductor solar cell element, and an organic solar cell element may be deteriorated by moisture and oxygen. Therefore, by covering the solar cell element 6 with the gas barrier film 3, the solar cell element 6 can be protected from water and oxygen, and the power generation capacity can be kept high.

The degree of moisture resistance required for the gas barrier film 3 varies depending on the type of the solar cell element 6 and the like. For example, when the solar cell element 6 is a compound semiconductor solar cell element, the water vapor transmission rate per unit area (1 m ² ) per day is 1 × 10 ⁻¹ g / m ² / day or less. Is preferably 1 × 10 ⁻² g / m ² / day or less, more preferably 1 × 10 ⁻³ g / m ² / day or less, and further preferably 1 × 10 ⁻⁴ g / m ^2. / Day or less is preferable, 1 × 10 ⁻⁵ g / m ² / day or less is particularly preferable, and 1 × 10 ⁻⁶ g / m ² / day or less is particularly preferable. Moreover, when the solar cell element 6 is an organic solar cell element, the water vapor permeability per unit area (1 m ² ) per day is preferably 1 × 10 ⁻¹ g / m ² / day or less. It is more preferably 1 × 10 ⁻² g / m ² / day or less, further preferably 1 × 10 ⁻³ g / m ² / day or less, and further preferably 1 × 10 ⁻⁴ g / m ² / day. Among them, the following is particularly preferable, and 1 × 10 ⁻⁵ g / m ² / day or less is particularly preferable, and 1 × 10 ⁻⁶ g / m ² / day or less is particularly preferable. As the water vapor does not pass through, deterioration due to the reaction of the solar cell element 6 and the transparent electrode such as ZnO: Al of the element 6 with water is suppressed, so that the power generation efficiency is increased and the life is extended.

The degree of oxygen permeability required for the gas barrier film 3 varies depending on the type of the solar cell element 6 and the like. For example, when the solar cell element 6 is a compound semiconductor solar cell element, the oxygen permeability per unit area (1 m ² ) per day is 1 × 10 ⁻¹ cc / m ² / day / atm or less. Preferably, it is 1 × 10 ⁻² cc / m ² / day / atm or less, more preferably 1 × 10 ⁻³ cc / m ² / day / atm or less, and further preferably 1 × 10 2. ⁻⁴ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁵ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁶ cc / m ² / day. / Atm or less is particularly preferable. For example, when the solar cell element 6 is an organic solar cell element, the oxygen permeability per unit area (1 m ² ) per day is 1 × 10 ⁻¹ cc / m ² / day / atm or less. Preferably, it is 1 × 10 ⁻² cc / m ² / day / atm or less, more preferably 1 × 10 ⁻³ cc / m ² / day / atm or less, and further preferably 1 × 10 2. ⁻⁴ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁵ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁶ cc / m ² / day. / Atm or less is particularly preferable. The deterioration due to oxidation of the solar cell element 6 and the transparent electrode such as ZnO: Al of the element 6 is suppressed as the oxygen does not permeate.

  Conventionally, it has been difficult to mount the gas barrier film 3 having such a high moisture-proof and oxygen-blocking capability, so that a solar cell including an excellent solar cell element such as a compound semiconductor solar cell element and an organic solar cell element is realized. Although it was difficult to carry out, implementation of the thin film solar cell 100 making use of excellent properties such as a compound semiconductor solar cell element and an organic solar cell element is facilitated by applying such a gas barrier film 3.

  Further, the gas barrier film 3 is preferably one that transmits visible light from the viewpoint of not preventing the light absorption of the solar cell element 6. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

  Furthermore, since the thin film solar cell 100 is often heated by receiving light, the gas barrier film 3 also preferably has heat resistance. From this viewpoint, the melting point of the constituent material of the gas barrier film 3 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably. It is 300 degrees C or less. By increasing the melting point, it is possible to reduce the possibility that the gas barrier film 3 melts and deteriorates when the thin film solar cell 100 is used.

The specific configuration of the gas barrier film 3 is arbitrary as long as the solar cell element 6 can be protected from water. However, since the production cost increases as the amount of water vapor or oxygen that can permeate the gas barrier film 3 increases, it is preferable to use an appropriate film considering these points comprehensively.
Hereinafter, the configuration of the gas barrier film 3 will be described with examples.

Two examples of the configuration of the gas barrier film 3 are preferable.
The first example is a film in which an inorganic barrier layer is disposed on a plastic film substrate. In this case, the inorganic barrier layer may be formed only on one side of the plastic film substrate, or may be formed on both sides of the plastic film substrate. When forming on both surfaces, the number of inorganic barrier layers formed on both surfaces may be the same or different.

  The second example is a film in which a unit layer composed of two layers in which an inorganic barrier layer and a polymer layer are arranged adjacent to each other is formed on a plastic film substrate. At this time, a unit layer composed of two layers in which an inorganic barrier layer and a polymer layer are arranged adjacent to each other is regarded as one unit, and this unit layer is composed of one unit (one inorganic barrier layer and one polymer layer are combined into one unit). (Meaning of unit) may be formed, but two or more units may be formed. For example, 2 to 5 units may be laminated.

  The unit layer may be formed only on one side of the plastic film substrate, or may be formed on both sides of the plastic film substrate. When forming on both surfaces, the numbers of inorganic barrier layers and polymer layers formed on both surfaces may be the same or different. In addition, when forming a unit layer on a plastic film substrate, an inorganic barrier layer may be formed and then a polymer layer may be formed thereon, or after forming a polymer layer and forming an inorganic barrier layer. Also good.

(Plastic film substrate)
The plastic film substrate used for the gas barrier film 3 is not particularly limited as long as it is a film that can hold the above-described inorganic barrier layer and polymer layer, and can be appropriately selected from the purpose of use of the gas barrier film 3 and the like.

  Examples of plastic film base materials include polyester resin, methacrylic resin, methacrylic acid-maleic acid copolymer, polystyrene, transparent fluororesin, polyimide resin, fluorinated polyimide resin, polyamide resin, polyvinyl alcohol resin, polyamideimide. Resin, polyetherimide resin, cellulose acylate resin, polyurethane resin, polyether ether ketone resin, polycarbonate resin, alicyclic polyolefin resin, polyarylate resin, polyether sulfone resin, polysulfone resin, cycloolefin copolymer, fluorene ring modified polycarbonate Examples thereof include thermoplastic resins such as resins, alicyclic modified polycarbonate resins, and acryloyl compounds.

Among these resins, preferred examples include polyester resins, polyarylate resins, polyethersulfone resins, fluorene ring-modified polycarbonate resins, alicyclic modified polycarbonate resins, and acryloyl compounds. It is also preferable to use a condensation polymer containing spirobiindane or spirobichroman. Among the polyester resins, biaxially stretched polyethylene terephthalate (PET) and biaxially stretched polyethylene naphthalate (PEN) are preferably used as the plastic film substrate in the present invention because of excellent thermal dimensional stability. It is done.
In addition, 1 type may be used for the material of a plastic film base material, and 2 or more types may be used together by arbitrary combinations and a ratio.

  The thickness of the plastic film substrate is not particularly defined, but is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility.

  The plastic film substrate is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

  An anchor coat agent layer (anchor coat layer) may be formed on the plastic film substrate in order to improve adhesion to the inorganic barrier layer. Usually, the anchor coat layer is formed by applying an anchor coat agent. Examples of the anchor coating agent include polyester resins, urethane resins, acrylic resins, oxazoline group-containing resins, carbodiimide group-containing resins, epoxy group-containing resins, isocyanate-containing resins, and copolymers thereof. Among these, a combination of at least one of a polyester resin, a urethane resin, and an acrylic resin and at least one of an oxazoline group-containing resin, a carbodiimide group-containing resin, an epoxy group-containing resin, and an isocyanate group-containing resin is preferable. In addition, an anchor coat agent may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

The thickness of the anchor coat layer is usually 0.005 μm or more, preferably 0.01 μm or more, and usually 5 μm or less, preferably 1 μm or less. If the thickness is less than or equal to the upper limit of this range, the slipperiness is good, and there is almost no peeling from the plastic film substrate due to the internal stress of the anchor coat layer itself. Moreover, if it is the thickness more than the lower limit of this range, a uniform thickness can be maintained and it is preferable.
Also, in order to improve the applicability and adhesion of the anchor coating agent to the plastic film substrate, the plastic film substrate may be subjected to a surface treatment such as normal chemical treatment or electric discharge treatment before application of the anchor coating agent. Good.

(Inorganic barrier layer)
The inorganic barrier layer is usually a layer formed of a metal oxide, nitride or oxynitride. In addition, the metal oxide, nitride, and oxynitride which form an inorganic barrier layer may be 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
Examples of the metal oxide include oxides such as Si, Al, Mg, In, Ni, Sn, Zn, Ti, Cu, Ce, and Ta, nitrides, and oxynitrides. Among these, in order to achieve both high barrier properties and high transparency, it is preferable to include aluminum oxide or silicon oxide, and it is particularly preferable to include silicon oxide from the viewpoint of moisture permeability and light transmittance.

The ratio of each metal atom to oxygen atom is also arbitrary, but in order to improve the transparency of the inorganic barrier layer and prevent coloring, the oxygen atom ratio should be extremely small from the stoichiometric ratio of the oxide. Is desirable. On the other hand, in order to improve the denseness of the inorganic barrier layer and increase the barrier property, it is desirable to reduce oxygen atoms. From this viewpoint, for example, when SiO _x is used as the metal oxide, the value of x is particularly preferably 1.5 to 1.8. For example, when AlO _x is used as the metal oxide, the value of x is particularly preferably 1.0 to 1.4.

  Moreover, when an inorganic barrier layer is comprised from 2 or more types of metal oxides, it is desirable to contain aluminum oxide and silicon oxide as a metal oxide. Among them, when the inorganic barrier layer is made of aluminum oxide and silicon oxide, the ratio of aluminum to silicon in the inorganic barrier layer can be arbitrarily set, but the ratio of Si / Al is usually 1/9 or more, preferably 2/8 or more, and usually 9/1 or less, preferably 2/8 or less.

  When the thickness of the inorganic barrier layer is increased, the barrier property tends to be increased. However, it is desirable to reduce the thickness in order to prevent cracking and prevent cracking when bent. Therefore, the appropriate thickness of the inorganic barrier layer is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably 200 nm or less.

  Although there is no restriction | limiting in the film-forming method of an inorganic barrier layer, Generally, it can carry out by sputtering method, a vacuum evaporation method, an ion plating method, plasma CVD method etc. For example, the sputtering method can be formed by a reactive sputtering method using plasma using one or more metal targets and oxygen gas as raw materials.

(Polymer layer)
Any polymer can be used for the polymer layer, and for example, a film that can be formed in a vacuum chamber can be used. In addition, the polymer which comprises a polymer layer may use 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  A wide variety of compounds can be used as the compound that gives the polymer, and examples include the following (i) to (vii). In addition, 1 type may be used for a monomer and it may use 2 or more types together by arbitrary combinations and a ratio.

(I) Examples include siloxanes such as hexamethyldisiloxane. An example of a method for forming a polymer layer in the case of using hexamethyldisiloxane is to introduce hexamethyldisiloxane as a vapor into a parallel plate type plasma apparatus using an RF electrode, to cause a polymerization reaction in the plasma, The polymer layer can be formed as a polysiloxane thin film by being deposited on a plastic film substrate.

(Ii) Examples include paraxylylene such as diparaxylylene. As an example of a method for forming a polymer layer in the case of using diparaxylylene, first, the vapor of diparaxylylene is heated at 650 ° C. to 700 ° C. in a high vacuum to generate thermal radicals. And the polymer layer can be formed by guiding the radical monomer vapor into the chamber and adsorbing it on the plastic film substrate, and at the same time proceeding radical polymerization reaction to deposit polyparaxylylene.

(Iii) For example, a monomer capable of alternately repeating addition polymerization of two kinds of monomers can be mentioned. The polymer thus obtained is a polyaddition polymer. Examples of the polyaddition polymer include polyurethane (diisocyanate / glycol), polyurea (diisocyanate / diamine), polythiourea (dithioisocyanate / diamine), polythioether urethane (bisethyleneurethane / dithiol), polyimine ( Bisepoxy / primary amine), polypeptide amide (bisazolactone / diamine), polyamide (diolefin / diamide) and the like.

(Iv) For example, an acrylate monomer can be mentioned. The acrylate monomer includes monofunctional, bifunctional, and polyfunctional acrylate monomers, and any of them may be used. However, in order to obtain an appropriate evaporation rate, degree of cure, cure rate, and the like, it is preferable to use a combination of two or more of the above acrylate monomers.
Examples of monofunctional acrylate monomers include aliphatic acrylate monomers, alicyclic acrylate monomers, ether acrylate monomers, cyclic ether acrylate monomers, aromatic acrylate monomers, hydroxyl group-containing acrylate monomers, carboxy group-containing acrylate monomers, and the like. There are, but any can be used.

(V) Monomers capable of obtaining a photocationically cured polymer, such as epoxy and oxetane, are exemplified. As an epoxy-type monomer, an alicyclic epoxy-type monomer, a bifunctional monomer, a polyfunctional oligomer etc. are mentioned, for example. Examples of the oxetane monomer include monofunctional oxetane, bifunctional oxetane, and oxetane having a silsesquioxane structure.

(Vi) An example is vinyl acetate. When vinyl acetate is used as a monomer, polyvinyl alcohol is obtained by saponifying the polymer, and this polyvinyl alcohol can be used as a polymer.

(Vii) Examples thereof include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride and itaconic anhydride. These constitute a copolymer with ethylene, and the copolymer can be used as a polymer. Furthermore, a mixture thereof, a mixture obtained by mixing glycidyl ether compounds, and a mixture with an epoxy compound can also be used as the polymer.

  There is no restriction | limiting in the polymerization method of a monomer when superposing | polymerizing the said monomer and producing | generating a polymer. However, the polymerization is usually carried out after a composition containing a monomer is applied or deposited to form a film. As an example of the polymerization method, when a thermal polymerization initiator is used, the polymerization is started by contact heating with a heater or the like; radiation heating with infrared rays, microwaves or the like; Moreover, when a photoinitiator is used, an active energy ray is irradiated and polymerization is started. Various light sources can be used when irradiating active energy rays, such as mercury arc lamps, xenon arc lamps, fluorescent lamps, carbon arc lamps, tungsten-halogen radiation lamps, and sunlight irradiation light. Can do. Further, electron beam irradiation or atmospheric pressure plasma treatment can also be performed.

Examples of the method for forming the polymer layer include a coating method and a vacuum film forming method.
When the polymer layer is formed by a coating method, for example, methods such as roll coating, gravure coating, knife coating, dip coating, curtain flow coating, spray coating, and bar coating can be used. Moreover, you may make it apply | coat the coating liquid for polymer layer formation in mist form. In this case, the average particle size of the droplets may be adjusted to an appropriate range. For example, when forming a coating liquid containing a polymerizable monomer in the form of a mist on a plastic film substrate, the droplets The average particle size of is 5 μm or less, preferably 1 μm or less.
On the other hand, when forming a polymer layer by a vacuum film-forming method, film-forming methods, such as vapor deposition and plasma CVD, are mentioned, for example.

  The thickness of the polymer layer is not particularly limited, but is usually 10 nm or more, and is usually 5000 nm or less, preferably 2000 nm or less, more preferably 1000 nm or less. By increasing the thickness of the polymer layer, the uniformity of the thickness can be easily obtained, and structural defects of the inorganic barrier layer can be efficiently filled with the polymer layer, and the barrier property tends to be improved. In addition, by reducing the thickness of the polymer layer, the barrier property can be improved because the polymer layer itself is less likely to crack due to an external force such as bending.

Particularly suitable gas barrier film 3 includes, for example, a film obtained by vacuum-depositing SiO _x on a base film such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).
In addition, the gas barrier film 3 may be formed with 1 type of material, and may be formed with 2 or more types of materials. The gas barrier film 3 may be formed of a single layer film, but may be a laminated film including two or more layers.

  The thickness of the gas barrier film 3 is not particularly defined, but is usually 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and is usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase gas barrier properties, and decreasing the thickness tends to increase flexibility and improve visible light transmittance.

  If the gas barrier film 3 can cover the solar cell element 6 and protect it from moisture and oxygen, the formation position is not limited, but the front surface of the solar cell element 6 (surface on the light receiving surface side, lower surface in FIG. 1) and It is preferable to cover the back surface (surface opposite to the light receiving surface; upper surface in FIG. 1). This is because the front and back surfaces of the thin film solar cell 100 are often formed in a larger area than the other surfaces. In this embodiment, the gas barrier film 3 covers the front surface of the solar cell element 6, and a gas barrier film 9 described later covers the back surface of the solar cell element 6. Then, the edges of the gas barrier films 3 and 9 are sealed with the sealing material 11, and the solar cell elements 6 are placed in the space surrounded by the gas barrier films 3 and 9 and the sealing material 11, so that the solar cell elements 6 It can be protected from oxygen. In addition, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. .

[Getter material film 4]
The getter material film 4 is a film that absorbs moisture and / or oxygen. Some components of the solar cell element 6 are deteriorated by moisture as described above, and some are deteriorated by oxygen. Therefore, by covering the solar cell element 6 with the getter material film 4, the solar cell element 6 and the like are protected from moisture and / or oxygen, and the power generation capacity is kept high.

Here, unlike the gas barrier film 3 as described above, the getter material film 4 does not prevent moisture permeation but absorbs moisture. By using a film that absorbs moisture, when the solar cell element 6 is covered with the gas barrier film 3 or the like, the getter material film 4 absorbs moisture that slightly enters the space formed by the gas barrier films 3 and 9 and the sealing material 11. Can be captured and the influence of moisture on the solar cell element 6 can be eliminated.
The degree of water absorption capacity of the getter material film 4 is usually 0.1 mg / cm ² or more, preferably 0.5 mg / cm ² or more, more preferably 1 mg / cm ² or more. The higher this value, the higher the water absorption capacity, and the deterioration of the solar cell element 6 can be suppressed. Moreover, although there is no restriction | limiting in an upper limit, it is usually 10 mg / cm < ² > or less.

  Further, when the getter material film 4 absorbs oxygen, when the solar cell element 6 is covered with the gas barrier films 3, 9, etc., it slightly enters the space formed by the gas barrier films 3, 9 and the seal material 11. Oxygen is captured by the getter material film 4 and the influence of the oxygen on the solar cell element 6 can be eliminated.

  Furthermore, the getter material film 4 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

  Furthermore, since the thin film solar cell 100 is often heated by receiving light, the getter material film 4 preferably has heat resistance. From this viewpoint, the melting point of the constituent material of the getter material film 4 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably. Is 300 ° C. or lower. By increasing the melting point, it is possible to reduce the possibility that the getter material film 4 is melted and deteriorated when the thin film solar cell 100 is used.

The material constituting the getter material film 4 is arbitrary as long as it can absorb moisture and / or oxygen. Examples of the material include alkali metal, alkaline earth metal, alkaline earth metal oxide, alkali metal or alkaline earth metal hydroxide, silica gel, zeolite compound, magnesium sulfate as a substance that absorbs moisture. And sulfates such as sodium sulfate and nickel sulfate, and organometallic compounds such as aluminum metal complexes and aluminum oxide octylates. Specifically, examples of the alkaline earth metal include Ca, Sr, and Ba. Examples of the alkaline earth metal oxide include CaO, SrO, and BaO. In addition, Zr-Al-BaO, an aluminum metal complex, etc. are also mentioned. Specific product names include, for example, OleDry (Futaba Electronics).
Examples of the substance that absorbs oxygen include activated carbon, silica gel, activated alumina, molecular sieve, magnesium oxide, and iron oxide. In addition, Fe, Mn, Zn, and inorganic salts such as sulfates, chlorides, and nitrates of these metals are also included.
In addition, the getter material film 4 may be formed of one type of material or may be formed of two or more types of materials. The getter material film 4 may be formed of a single layer film, but may be a laminated film including two or more layers.

  The thickness of the getter material film 4 is not particularly specified, but is usually 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility.

  If the getter material film 4 is in the space formed by the gas barrier films 3, 9 and the sealing material 11, the formation position is not limited. However, the front surface of the solar cell element 6 (surface on the light receiving surface side; lower in FIG. 1). Side surface) and back surface (surface opposite to the light receiving surface; upper surface in FIG. 1) is preferably covered. This is because, in the thin film solar cell 100, the front and back surfaces are often formed in a larger area than the other surfaces, and therefore moisture and oxygen tend to enter through these surfaces. From this viewpoint, the getter material film 4 is preferably provided between the gas barrier film 3 and the solar cell element 6. In this embodiment, the getter material film 4 covers the front surface of the solar cell element 6, a getter material film 8 described later covers the back surface of the solar cell element 6, and the getter material films 4 and 8 are respectively the solar cell element 6 and the gas barrier film 3. , 9 are located between them. In addition, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. .

  The getter material film 4 can be formed by any method depending on the type of the water-absorbing agent or desiccant. For example, a method of attaching a film in which the water-absorbing agent or desiccant is dispersed with an adhesive, water-absorbing agent or desiccant A method of applying the solution by a spin coating method, an inkjet method, a dispenser method, or the like can be used. A film forming method such as a vacuum evaporation method or a sputtering method may be used.

  Examples of the film for the water absorbing agent or the drying agent include polyethylene resins, polypropylene resins, cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymers (AS resins), and acrylonitrile-butadiene-styrene copolymers. (ABS resin), polyvinyl chloride resin, fluorine resin, poly (meth) acrylic resin, polycarbonate resin, and the like can be used. Among these, films of polyethylene resin, fluorine resin, cyclic polyolefin resin, and polycarbonate resin are preferable. In addition, the said resin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

[Sealing material 5]
The sealing material 5 is a film that reinforces the solar cell element 6. Since the solar cell element 6 is thin, the strength is usually weak, and thus the strength of the thin film solar cell tends to be weak. However, the strength can be maintained high by the sealing material 5.

Moreover, it is preferable that the sealing material 5 has high strength from the viewpoint of maintaining the strength of the thin-film solar cell 100.
The specific strength is related to the strength of the weatherproof protective film 1 other than the sealing material 5 and the strength of the back sheet 10 and is generally difficult to define, but the thin film solar cell 100 as a whole has good bending workability. However, it is desirable to have a strength that does not cause peeling of the bent portion.

  In addition, the sealing material 5 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

  Furthermore, since the thin film solar cell 100 is often heated by receiving light, it is preferable that the sealing material 5 also has heat resistance. From this viewpoint, the melting point of the constituent material of the sealing material 5 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably. Is 300 ° C. or lower. By increasing the melting point, the possibility that the sealing material 5 is melted and deteriorated when the thin film solar cell 100 is used can be reduced.

  The thickness of the sealing material 5 is not particularly defined, but is usually 100 μm or more, preferably 150 μm or more, more preferably 200 μm or more, and usually 700 μm or less, preferably 600 μm or less, more preferably 500 μm or less. Increasing the thickness tends to increase the strength of the thin-film solar cell 100 as a whole, and decreasing the thickness tends to increase flexibility and improve visible light transmittance.

  As a material which comprises the sealing material 5, what used the ethylene-vinyl acetate copolymer (EVA) resin composition for the film (EVA film) etc. can be used, for example. In order to improve weather resistance, the EVA film is usually blended with a crosslinking agent to form a crosslinked structure. As the crosslinking agent, an organic peroxide that generates radicals at 100 ° C. or higher is generally used. Examples of such an organic peroxide include 2,5-dimethylhexane; 2,5-dihydroperoxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane; Di-t-butyl peroxide or the like can be used. The compounding amount of these organic peroxides is usually 5 parts by weight or less, preferably 3 parts by weight or less, and usually 1 part by weight or more with respect to 100 parts by weight of the EVA resin. In addition, 1 type may be used for a crosslinking agent and it may use 2 or more types together by arbitrary combinations and a ratio.

  This EVA resin composition may contain a silane coupling agent for the purpose of improving the adhesive strength. Examples of silane coupling agents used for this purpose include γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyl-tris- (β-methoxyethoxy) silane; γ-methacryloxypropyltri Methoxysilane; β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane and the like can be mentioned. The compounding amount of these silane coupling agents is usually 5 parts by weight or less, preferably 2 parts by weight or less, and usually 0.1 parts by weight or more with respect to 100 parts by weight of the EVA resin. In addition, 1 type may be used for a silane coupling agent and it may use 2 or more types together by arbitrary combinations and a ratio.

  Furthermore, in order to improve the gel fraction of the EVA resin and improve the durability, a crosslinking aid may be included in the EVA resin composition. Examples of the crosslinking aid provided for this purpose include monofunctional crosslinking aids such as trifunctional crosslinking aids such as triallyl isocyanurate and triallyl isocyanate. The amount of these crosslinking aids is usually 10 parts by weight or less, preferably 5 parts by weight or less, and usually 1 part by weight or more with respect to 100 parts by weight of the EVA resin. In addition, 1 type may be used for a crosslinking adjuvant, and 2 or more types may be used together by arbitrary combinations and a ratio.

  Furthermore, for the purpose of improving the stability of the EVA resin, the EVA resin composition may contain, for example, hydroquinone; hydroquinone monomethyl ether; p-benzoquinone; methyl hydroquinone. These compounding quantities are normally 5 weight part or less with respect to 100 weight part of EVA resin.

  However, since the EVA resin cross-linking treatment requires a relatively long time of about 1 to 2 hours, it may cause a reduction in the production rate and production efficiency of the thin-film solar cell 100. Further, when used for a long period of time, the decomposition gas (acetic acid gas) of the EVA resin composition or the vinyl acetate group of the EVA resin itself may adversely affect the solar cell element 6 and reduce the power generation efficiency. Therefore, as the sealing material 5, in addition to the EVA film, a copolymer film made of a propylene / ethylene / α-olefin copolymer can also be used. As this copolymer, the thermoplastic resin composition with which the following component 1 and the component 2 were mix | blended is mentioned, for example.

Component 1: The propylene polymer is usually 0 part by weight or more, preferably 10 parts by weight or more, and usually 70 parts by weight or less, preferably 50 parts by weight or less.
Component 2: The soft propylene copolymer is 30 parts by weight or more, preferably 50 parts by weight or more, and is usually 100 parts by weight or less, preferably 90 parts by weight or less.
The total amount of component 1 and component 2 is 100 parts by weight. As described above, when component 1 and component 2 are in a preferred range, the moldability of the encapsulant 5 into a sheet is good, and the resulting encapsulant 5 has good heat resistance, transparency, and flexibility. Thus, the thin film solar cell 100 is suitable.
Hereinafter, component 1 and component 2 will be described in detail.

[Component 1]
Component 1 is a propylene-based polymer, and examples thereof include a propylene homopolymer; a copolymer of propylene and at least one α-olefin having 2 to 20 carbon atoms other than propylene. Here, as the α-olefin having 2 to 20 carbon atoms other than propylene, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-octene, Examples include decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene. Among these, ethylene or an α-olefin having 4 to 10 carbon atoms is preferable. In addition, alpha-olefin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  These α-olefins may form a random copolymer with propylene or a block copolymer. The proportion of the constituent units derived from these α-olefins is usually 35 mol% or less, preferably 30 mol% or less in the polypropylene.

  Component 1 has a melt flow rate (MFR) measured at 230 ° C. and a load of 2.16 kg in accordance with ASTM D 1238, usually 0.01 g / 10 min or more, preferably 0.05 g / 10 min or more. Usually, it is 1000 g / 10 min or less, preferably 100 g / 10 min or less.

  The melting point observed by the differential scanning calorimeter of component 1 is usually 100 ° C. or higher, preferably 110 ° C. or higher, and is usually 160 ° C. or lower, preferably 150 ° C. or lower.

Component 1 can use either an isotactic structure or a syndiotactic structure, but the isotactic structure is preferred in view of heat resistance and the like.
Further, as the component 1, a plurality of propylene polymers can be used in combination as necessary, and for example, two or more types of components having different melting points and rigidity can be used.

[Component 2]
Component 2 is a soft propylene-based copolymer, and examples thereof include a copolymer of propylene and at least one α-olefin having 2 to 20 carbon atoms other than propylene.
Component 2 has a Shore A hardness of usually 30 or more, preferably 35 or more, and usually 80 or less, preferably 70 or less.
Furthermore, the melting point observed with the differential scanning calorimeter DSC of component 2 is less than 100 ° C. or no melting point is observed. Here, that the melting point is not observed means that a crystal melting peak having a heat of crystal melting of 1 J / g or more is not observed in the range of −150 to 200 ° C.

In Component 2, the α-olefin used as a comonomer is preferably, for example, ethylene and / or an α-olefin having 4 to 20 carbon atoms. In addition, alpha-olefin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
Component 2 contains propylene-derived units usually 45 mol% or more, preferably 56 mol% or more, and usually 92 mol% or less, preferably 90 mol% or less, and usually contains α-olefin-derived units used as a comonomer. 8 mol% or more, preferably 10 mol% or more, and usually 55 mol% or less, preferably 44 mol% or less.

  Component 2 has a melt flow rate (MFR) measured at 230 ° C. and a load of 2.16 kg, usually 0.01 g / 10 min or more, preferably 0.05 g / 10 min or more, in accordance with ASTM D 1238. In addition, it is usually 100 g / 10 min or less, preferably 50 g / 10 min or less.

  Component 2 is based on JIS K6301, using a JIS No. 3 dumbbell, span: 30 mm, tensile speed: 30 mm / min, measured at 23 ° C., stress at 100% strain (M100) is usually 4 MPa. Hereinafter, it is preferably 3 MPa or less, more preferably 2 MPa or less. When the soft propylene copolymer is in such a range, the flexibility, transparency, and rubber elasticity are excellent.

Component 2 has a crystallinity measured by X-ray diffraction of usually 20% or less, preferably 15% or less, and usually 0% or more.
Component 2 has a single glass transition temperature Tg, and the glass transition temperature Tg measured by a differential scanning calorimeter (DSC) is usually in the range of −10 ° C. or lower, preferably −15 ° C. or lower. Is desirable. When the glass transition temperature Tg of Component 2 is within the above range, the cold resistance and low temperature characteristics are excellent.

  The molecular weight distribution (Mw / Mn, polystyrene conversion, Mw: weight average molecular weight, Mn: number average molecular weight) measured by GPC of Component 2 is preferably 4.0 or less, more preferably 3.0 or less, and further Preferably it is 2.5 or less.

Component 2 usually has a heat of fusion ΔH of 30 J / g or less and a C3 (propylene) content when a melting point (Tm, ° C.) exists in an endothermic curve in a differential scanning calorimeter (DSC). It is preferable that the following relational expression holds for the relationship between (mol%) and the heat of fusion ΔH (J / g).
ΔH <345Ln (C3 content mol%)-1492,
(However, in this case, 76 ≦ C3 content (mol%) ≦ 90)

  Preferred specific examples of component 2 include the following propylene / ethylene / α-olefin copolymers. By using such a propylene / ethylene / α-olefin copolymer, the sealing material 5 having good flexibility, heat resistance, mechanical strength, solar cell sealing property and transparency can be obtained. Here, the solar cell sealing property means that the cracking rate of the element when the solar cell element 6 is filled can be reduced with good flexibility.

  As propylene / ethylene / α-olefin copolymer, propylene-derived structural units are usually 45 mol% or more, preferably 56 mol% or more, more preferably 61 mol% or more, and usually 92 mol% or less, preferably 90 mol% or less, more preferably 86 mol% or less, and further ethylene-derived structural units are usually 5 mol% or more, preferably 8 mol% or more, and usually 25 mol% or less, preferably 14 mol% or less, more Preferably, it contains 14 mol% or less, and the structural unit derived from an α-olefin having 4 to 20 carbon atoms is usually 3 mol% or more, preferably 5 mol% or more, more preferably 6 mol% or more, and usually 30 mol% or less. , Preferably those containing 25 mol% or less. With regard to α-olefins, 1-butene is particularly preferred.

  A propylene / ethylene / α-olefin copolymer (component 2) containing a propylene-derived structural unit, an ethylene-derived structural unit, and a structural unit derived from an α-olefin having 4 to 20 carbon atoms in the above amount is propylene. The compatibility with the system polymer (component 1) becomes good, and the obtained sealing material 5 exhibits sufficient transparency, flexibility, heat resistance and scratch resistance.

The thermoplastic resin composition in which the above component 1 and component 2 are blended has a melt flow rate (ASTM D 1238, 230 degrees, load 2.16 kg) of usually 0.0001 g / 10 min or more. It is 1000 g / 10 min or less, preferably 900 g / 10 min or less, more preferably 800 g / 10 min or less.
The melting point of the thermoplastic resin composition containing component 1 and component 2 is usually 100 ° C. or higher, preferably 110 ° C. or higher. Moreover, it is 140 degrees C or less normally, Preferably it is 135 degrees C or less.
Density of The thermoplastic resin composition Components 1 and 2 were compounded is preferably from 0.98 g / cm ³ or less, more preferably 0.95 g / cm ³ or less, more preferably 0.94 g / cm ³ or less .

  In this sealing material 5, it is possible to mix | blend a coupling agent with the said component 1 and component 2 as an adhesion promoter with respect to a plastics. As the coupling agent, silane, titanate, and chromium coupling agents are preferably used, and a silane coupling agent (silane coupling agent) is particularly preferably used.

  Known silane coupling agents can be used and are not particularly limited. For example, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxy-ethoxysilane), γ-glycidoxypropyl-tri Examples include piltrimethoxysilane and γ-aminopropyltriethoxysilane. In addition, 1 type may be used for a coupling agent and it may use 2 or more types together by arbitrary combinations and a ratio.

  These are usually 0.1 parts by weight or more, usually 5 parts by weight or less, preferably 100 parts by weight of the silane coupling agent, based on 100 parts by weight of the thermoplastic resin composition (total amount of Component 1 and Component 2). It is desirable to contain 3 parts by weight or less.

The coupling agent may be grafted to the thermoplastic resin composition using an organic peroxide. In this case, it is desirable that 0.1 to 5 parts by weight of the coupling agent is included with respect to 100 parts by weight of the thermoplastic resin composition (total amount of Component 1 and Component 2). Even if a silane-grafted thermoplastic resin composition is used, the same or better adhesion to glass and plastic as the silane coupling agent blend can be obtained.
When the organic peroxide is used, the organic peroxide is usually 0.001 part by weight or more, preferably 0.01 part by weight with respect to 100 parts by weight of the thermoplastic resin composition (total amount of Component 1 and Component 2). Part or more, and usually 5 parts by weight or less, preferably 3 parts by weight or less.

  Known organic peroxides can be used and are not particularly limited. Examples thereof include dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, and dibenzoylperoxide. Examples thereof include oxide, t-amylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, and t-butylperoxymaleic acid. In addition, an organic peroxide may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

Further, a copolymer made of an ethylene / α-olefin copolymer can be used as the sealing material 5. As this copolymer, a laminate film having a hot tack property of 5 to 25 ° C., which is formed by laminating a resin composition for a sealing material comprising the following components A and B and a substrate, is exemplified.
Component A: ethylene resin.
Component B: a copolymer of ethylene and an α-olefin having the following properties (a) to (d).
(A) The density is 0.86 to 0.935 g / cm ³ .
(B) Melt flow rate (MFR) is 1 to 50 g / 10 min.
(C) There is one peak in the elution curve obtained by temperature rising elution fractionation (TREF); the peak temperature is 100 ° C. or lower.
(D) The integrated elution amount by temperature rising elution fractionation (TREF) is 90% or more at 90 ° C.

(A) Component A (ethylene-based resin)
Examples of the ethylene-based resin as the component A constituting the resin composition for a sealing material include high-pressure low-density polyethylene, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer produced by a so-called radical polymerization method. Examples thereof include an ethylene / acrylic acid ester copolymer and an ethylene / vinyl fluoride copolymer. Moreover, the polymer or copolymer which has ethylene as a main component, such as what is called linear low density polyethylene and high density polyethylene manufactured by the ionic polymerization method, is also mentioned. Among these, ethylene / vinyl acetate copolymer and high pressure method low density polyethylene are preferable. In addition, these may use 1 type and may use 2 or more types together by arbitrary combinations and ratios.

When the ethylene resin as component A constituting the resin composition for a sealing material is an ethylene / vinyl acetate copolymer, those having the following properties are suitable.
(I) Melt flow rate (MFR)
The MFR (melt flow rate: melt flow rate) according to JIS K7210 of the ethylene / vinyl acetate copolymer as component A constituting the resin composition for a sealing material is usually 1 g / 10 min or more, preferably 2 g. / 10 min or more, more preferably 3 g / 10 min or more, and usually 50 g / 10 min or less, preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less. Increasing the MFR tends to increase transparency when blended with the component B, and decreasing the MFR tends to facilitate molding.

(Ii) Vinyl acetate content The vinyl acetate content of the ethylene / vinyl acetate copolymer as component A constituting the resin composition for a sealing material is usually 3% by weight or more, preferably 4% by weight or more, more preferably 5%. It is usually not more than 30% by weight, preferably not more than 20% by weight, more preferably not more than 15% by weight. Increasing the vinyl acetate content tends to increase heat sealability, and reducing the vinyl acetate content can suppress stickiness of the sealing material 5.

When the ethylene-based resin as component A constituting the resin composition for a sealing material is a high-pressure method low-density polyethylene, those having the following properties are suitable.
(I) Melt flow rate (MFR)
The MFR (melt flow rate: melt flow rate) according to JIS K7210 of the high-pressure low-density polyethylene as component A constituting the resin composition for a sealing material is usually 1 g / 10 min or more, preferably 2 g / 10. Min. Or more, more preferably 3 g / 10 min or more, and usually 50 g / 10 min or less, preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less. It tends to be easy to extrude by increasing the MFR, and by reducing the MFR, the film becomes too soft and does not easily sag, and the moldability increases.

(Ii) Density by JIS K7112 of high-pressure low-density polyethylene as component A constituting the density encapsulant resin composition is usually 0.915 g / cm ³ or more, preferably 0.916 g / cm ³ or more, more preferably at 0.917 g / cm ³ or more and usually 0.93 g / cm ³ or less, preferably 0.925 g / cm ³ or less, more preferably 0.923 g / cm ³ or less. By increasing the density, stickiness of the sealing material 5 tends to be suppressed, and by decreasing the density, heat sealability tends to increase.

  As the high-pressure method low-density polyethylene as component A constituting the resin composition for a sealing material, those exhibiting the above physical properties can be appropriately selected from commercially available products.

(B) Component B (ethylene / α-olefin copolymer)
Component B constituting the resin composition for a sealing material is an ethylene / α-olefin copolymer other than Component A. Component B preferably has the following properties.

(I) Density The density according to JlS K7112 of the ethylene / α-olefin copolymer as component B constituting the resin composition for a sealing material is usually 0.86 g / cm ³ or more, preferably 0.87 g / cm ^3. or more, more preferably 0.88 g / cm ³ or more and usually 0.935 g / cm ³ or less, preferably 0.915 g / cm ³ or less, more preferably 0.91 g / cm ³ or less. By increasing the density, stickiness when used as a film tends to be suppressed, and by decreasing the density, heat sealability tends to increase.

(Ii) Melt flow rate (MFR)
The MFR (melt flow rate: melt flow rate) according to JLS K7210 of the ethylene / α-olefin copolymer as component B constituting the resin composition for a sealing material is usually 1 g / 10 min or more, preferably It is 2 g / 10 min or more, more preferably 3 g / 10 min or more, and is usually 50 g / 10 min or less, preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less. It tends to be easy to extrude by increasing the MFR, and by reducing the MFR, the film becomes too soft and does not easily sag, and the moldability increases.

  Here, the α-olefin is preferably an α-olefin having 4 to 40 carbon atoms. Among them, among α-olefins, those having usually 4 or more, preferably 6 or more, and usually 12 or less, preferably 10 or less are desirable. For example, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methylpentene-1, 4-methylhexene-1, 4,4-dimethylpentene-1, etc. Is mentioned. In addition, alpha-olefin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of α-olefin to ethylene is usually 2% by weight or more, preferably 5% by weight or more, more preferably 10% by weight or more, and usually 60% by weight or less, preferably 50% by weight or less. More preferably 30 wt% or less, ethylene is usually 40 wt% or more, preferably 50 wt% or more, more preferably 70 wt% or more, and usually 98 wt% or less, preferably 95 wt% or less, more preferably It is desirable that the content be 90% by weight or less.

  The blending ratio (component A / component B) of component A and component B is usually 50/50 or more, preferably 55/45 or more, more preferably 60/40 or more, and usually 99 / 1 or less, preferably 90/10 or less, more preferably 85/15 or less. Increasing the amount of component B tends to increase transparency and heat sealability, and decreasing the amount of component B tends to increase the workability of the film.

  The melt flow rate (MFR) of the resin composition for a sealing material produced by blending component A and component B is usually 2 g / 10 minutes or more, preferably 3 g / 10 minutes or more, and usually 50 g / 10 minutes. Hereinafter, it is preferably 40 g / 10 min or less. In addition, the measurement and evaluation of MFR can be implemented by the method based on JISK7210 (190 degreeC, 2.16kg load).

  The melting point of the encapsulant resin composition is preferably 50 ° C. or higher, more preferably 55 ° C. or higher, and is usually 300 ° C. or lower, preferably 250 ° C. or lower, more preferably 200 ° C. or lower. By increasing the melting point, the possibility of melting and deterioration during use of the thin film solar cell 100 can be reduced.

The density of the resin composition for a sealing material is preferably 0.80 g / cm ³ or more, more preferably 0.85 g / cm ³ or more, and preferably 0.98 g / cm ³ or less, 0.95 g / cm ^3. The following is more preferable, and 0.94 g / cm ³ or less is more preferable. The measurement and evaluation of density can be performed by a method based on JIS K7112.

  Further, in the encapsulant 5 using the ethylene / α-olefin copolymer, a coupling agent can be used as in the case of using the propylene / ethylene / α-olefin copolymer.

  Since the sealing material 5 described above does not generate a decomposition gas derived from the material, the solar cell element 6 is not adversely affected, and has good heat resistance, mechanical strength, flexibility (solar cell sealing property), and transparency. Have sex. In addition, since a material crosslinking step is not required, the manufacturing time of the thin film solar cell 100 during sheet molding can be greatly reduced, and the thin film solar cell 100 after use can be easily recycled.

  In addition, the sealing material 5 may be formed with 1 type of material, and may be formed with 2 or more types of materials. Moreover, although the sealing material 5 may be formed with the single layer film, the laminated | multilayer film provided with the film of 2 or more layers may be sufficient as it.

  The thickness of the sealing material 5 is usually 2 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 500 μm or less, preferably 300 μm or less, more preferably 100 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility and light transmittance.

  Although there is no restriction | limiting in the position which provides the sealing material 5, Usually, it provides so that the solar cell element 6 may be inserted | pinched. This is for reliably protecting the solar cell element 6. In this embodiment, the sealing material 5 and the sealing material 7 are provided on the front surface and the back surface of the solar cell element 6, respectively.

[Solar cell element 6]
The solar cell element 6 is an element that receives light and generates power. There is no restriction | limiting in the kind of solar cell element 6, For example, a thin film polycrystalline silicon type solar cell element, an amorphous silicon type solar cell element, a compound semiconductor type solar cell element, an organic solar cell element etc. can be used.

  However, the thin-film polycrystalline silicon solar cell element is a type of solar cell element utilizing indirect optical transition. For this reason, in a thin film polycrystalline silicon solar cell element, it is required to provide a sufficient light confinement structure such as forming an uneven structure on the substrate or the surface to increase light absorption. Furthermore, in thin-film polycrystalline silicon-based solar cell elements, for example, in order to enable thin film growth on low-cost substrates such as parallel glass and polymer thin films, it is possible to lower the temperature of the high-quality thin film manufacturing process. Required. For this reason, the thin film polycrystalline silicon solar cell element has room for improvement in terms of cost and the like for practical use.

  On the other hand, in the amorphous silicon solar cell element, the indirect optical transition in crystalline silicon is a direct transition due to structural disorder, and the optical absorption coefficient in the visible region is large, and even a thin film having a thickness of about 1 μm is sunlight. Has the advantage that it can be absorbed sufficiently. For this reason, if an amorphous silicon solar cell element is used as the solar cell element 6, a lightweight solar cell panel can be realized. Further, since amorphous silicon is an amorphous material, it is resistant to deformation of slats.

  However, the amorphous silicon solar cell element has a low mobility of carriers such as electrons and holes generated by light absorption due to structural disorder. In addition, although the dangling bonds of silicon serve as recombination centers for carriers, the amorphous silicon-based solar cell element has a short carrier life because of the high density of dangling bonds. Furthermore, the amorphous silicon solar cell element may be deteriorated by long-term light irradiation. Specifically, since the amorphous silicon solar cell element exhibits a phenomenon in which the density of the defects is further increased by light irradiation (that is, photodegradation phenomenon), the initial photoelectric conversion efficiency is about 10%. In addition to being less efficient, the photoelectric conversion efficiency tends to be reduced to about 8% by light irradiation (although saturation occurs).

Therefore, in the thin film solar cell 100 of the present embodiment, it is preferable to use a compound semiconductor solar cell element or an organic solar cell element as the solar cell element 6. Moreover, among the compound semiconductor-based solar cell devices, e.g. S, Se, preferably a chalcogenide-based solar cell element comprising a chalcogen element such as Te, inter alia I-III-VI ₂ group semiconductor system (chalcopyrite) solar cell element In particular, a Cu-III-VI group ₂ semiconductor solar cell element using Cu as a group I element is preferable because it has a theoretically higher photoelectric conversion efficiency than a Si crystal type solar cell.

[Cu-III-VI Group ₂ semiconductor solar cell element]
Cu-III-VI ₂ group semiconductor-based solar cell element refers to a solar cell element having a Cu-III-VI ₂ group semiconductor as a constituent material. The Cu-III-VI group ₂ semiconductor refers to a semiconductor composed of a compound containing Cu, a group III element, and a group VI element at a ratio of 1: 1: 2, for example, CuInSe ₂ , CuGaSe ₂ , Cu (In _{1− x Ga x) Se 2, CuInS} 2, CuGaS 2, Cu (In 1-x Ga x) S 2, CuInTe 2, CuGaTe 2, Cu (In 1-x Ga x) Te 2 and the like. A mixture of two or more of these may be used. Among these, a CIS solar cell element and a CIGS solar cell element are particularly preferable.

The CIS solar cell element refers to a solar cell having a CIS semiconductor as a constituent material, and the CIS semiconductor refers to CuIn (Se _1-y S _y ) ₂ . Note that y represents a number from 0 to 1. That is, it refers to CuInSe ₂ , CuInS ₂ , or those in a mixed state. Use of S instead of Se is preferable because safety is increased.
The CIGS solar cell element refers to a solar cell having a CIGS semiconductor as a constituent material. Here, the CIGS-based semiconductor _refers to a _{Cu (In 1-x Ga x} ) (Se 1-y S y) 2. X represents a number greater than 0 and less than 1, and y represents a number from 0 to 1. The _{Cu (In 1-x Ga x} ) Se 2 is usually a mixed crystal of CuInSe ₂ and CuGaSe _2. The range of x is usually greater than 0, preferably greater than 0.05, more preferably greater than 0.1, and usually less than 0.8, preferably less than 0.5, more preferably 0. Less than 4.

The Cu-III-VI Group ₂ semiconductor usually functions as a p-type semiconductor. Here, p-type and n-type semiconductors will be described. In semiconductors, there are two types of carriers that transport charges, electrons and holes, and the larger the density, the more carriers are called. Majority carriers are usually determined by the type of semiconductor and the doping state. As the semiconductor type, those in which majority carriers are electrons are called n-type, those in which holes are holes are called p-type, and those in which the majority carriers are balanced are called i-type.
However, the p-type and n-type are not absolutely determined by the type of semiconductor. For example, even when semiconductors of the same type are combined, one may operate as a p-type and the other as an n-type due to the relationship between energy levels (HOMO levels, LUMO levels, Fermi levels) and doping states. is there.

The degree of semiconductor characteristics exhibited by the semiconductor is usually 10 ⁻⁷ cm ² / Vs or more, preferably 10 ⁻⁵ cm ² / Vs or more in terms of carrier mobility. Since electrical conductivity is defined by carrier mobility x carrier density, any material having a certain level of carrier mobility may have carriers present in the material, for example, by heat, doping, or injection from an electrode. For example, the material can transport charges. Note that the higher the carrier mobility of the semiconductor, the better.

The Cu-III-VI group ₂ semiconductor is usually contained in at least one of the layers constituting the solar cell element 6, and the solar cell element 6 absorbs light by the layer containing the semiconductor to generate electricity. Is supposed to occur. A specific configuration of the solar cell element 6 will be described below with an example. However, the solar cell element 6 according to the present invention is not limited to the example described below.

For example, the Cu-III-VI group ₂ semiconductor solar cell element includes at least a light absorption layer and a buffer layer between a pair of electrodes. In the solar cell element having such a configuration, light is absorbed in the light absorption layer to generate electricity, and the generated electricity is taken out from the electrode.

-Electrode An electrode can be formed with the arbitrary materials which have electroconductivity. Examples of electrode materials include metals such as platinum, gold, silver, aluminum, chromium, nickel, copper, titanium, magnesium, calcium, barium, sodium, and alloys thereof; metal oxides such as indium oxide and tin oxide. Or alloys thereof (ITO); conductive polymers such as polyaniline, polypyrrole, polythiophene and polyacetylene; acids such as hydrochloric acid, sulfuric acid and sulfonic acid, Lewis acids such as FeCl ₃ and halogens such as iodine Materials containing a dopant such as metal atoms such as atoms, sodium and potassium; conductive composite materials in which conductive particles such as metal particles, carbon black, fullerene and carbon nanotubes are dispersed in a matrix such as a polymer binder It is done. In addition, the material of an electrode may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  In the solar cell element 6, at least a pair (two) of electrodes are provided. At this time, it is preferable that at least the electrode on the light receiving surface side of the pair of electrodes is transparent in order to transmit light for power generation. However, if the electrode is not transparent, such as the area of the electrode is smaller than the area of the power generation layer, it does not necessarily need to be transparent if the power generation performance is not adversely affected. Examples of transparent electrode materials include oxides such as ITO and indium zinc oxide (IZO); and metal thin films. At this time, the specific range of the light transmittance is not limited, but considering the power generation efficiency of the solar cell element 6, 80% or more is preferable. The light transmittance can be measured with a normal spectrophotometer.

  The electrode has a function of collecting holes and electrons generated by light absorption. Therefore, it is preferable to use an electrode material suitable for collecting holes and electrons for the electrode. Examples of the electrode material suitable for collecting holes include materials having a high work function such as Au and ITO. On the other hand, an electrode material suitable for collecting electrons includes a material having a low work function such as Al.

In addition, there is no restriction | limiting in the formation method of an electrode. For example, it can be formed by a dry process such as vacuum deposition or sputtering. Further, for example, it can be formed by a wet process using a conductive ink or the like. At this time, any conductive ink can be used. For example, a conductive polymer, a metal particle dispersion, or the like can be used.
Furthermore, two or more electrodes may be laminated, and characteristics (electric characteristics, wetting characteristics, etc.) due to surface treatment may be improved.

-Light absorption layer A light absorption layer is a layer containing the Cu-III-VI ₂ group semiconductor mentioned above. Usually, since a Cu-III-VI group ₂ semiconductor functions as a p-type semiconductor, it is possible to generate electricity by absorbing light by forming a buffer layer described later with an n-type semiconductor. Note that each of the Cu-III-VI group ₂ semiconductors may be formed of one kind, or two or more kinds may be used in any combination and ratio. Also, a CIS semiconductor and a CIGS semiconductor may be combined.

Usually, the light absorption layer is formed of only a Cu-III-VI group ₂ semiconductor, but may contain other components as long as the effects of the present invention are not significantly impaired. Examples thereof include additives such as Ag. In addition, the other component may contain 1 type and may contain 2 or more types by arbitrary combinations and ratios.

There is no restriction | limiting in the formation method of a light absorption layer. For example, it can be formed by vacuum deposition, sputtering, or the like.
Furthermore, although the light absorption layer usually forms only one layer, two or more layers may be laminated.

Buffer layer The buffer layer is a layer that is laminated so as to be in contact with the light absorption layer. If the semiconductor that the light absorption layer has is p-type, it is formed of an n-type semiconductor, and the semiconductor that the light absorption layer has is n-type. If present, it is formed of a p-type semiconductor. Usually, since the Cu-III-VI group ₂ semiconductor is a p-type semiconductor, the buffer layer in the Cu-III-VI group ₂ semiconductor solar cell element is formed of an n-type semiconductor.

Specific examples of the semiconductor forming the buffer layer include CdS, Zn _1-x Mg _x O (0 <x <0.8), ZnS (O, OH), InS, and the like. In addition, since the above-described CuInS ₂ can be formed as an n-type semiconductor layer by setting it to a composition deviating from the stoichiometric ratio depending on manufacturing conditions, it may be used as a buffer layer. In addition, the semiconductor which forms a buffer layer may be 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

There is no restriction | limiting in the formation method of a buffer layer. For example, it can be formed by vacuum deposition, sputtering, or the like.
Furthermore, the buffer layer usually forms only one layer, but two or more layers may be laminated.

[Organic solar cell element]
An organic solar cell element means a solar cell element having an organic semiconductor as a constituent material. Examples of the organic semiconductor include naphthalene (or perylene) tetracarboxylic acid diimide, fullerene (C ₆₀ ), and derivatives thereof.
Moreover, for example, conjugated polymers such as polythiophene, polyfluorene, polythienylene vinylene, polyacetylene, and polyaniline; and polymer semiconductors such as alkyl-substituted oligothiophene are also included. These are semiconductors that are soluble in an organic solvent, and are preferable because a coating method can be used in the manufacturing process of an organic solar cell element.
Furthermore, for example, condensed aromatic hydrocarbons such as naphthacene, pentacene, pyrene, fullerene; oligothiophenes containing 4 or more thiophene rings such as α-sexithiophene; thiophene ring, benzene ring, fluorene ring, naphthalene ring, anthracene Rings, thiazole rings, thiadiazole rings, benzothiazole rings in total of 4 or more; aromatics such as naphthalene tetracarboxylic acid anhydride, naphthalene tetracarboxylic acid diimide, perylene tetracarboxylic acid anhydride, perylene tetracarboxylic acid diimide Examples thereof include carboxylic acid anhydrides and imidized products thereof; phthalocyanine compounds such as copper phthalocyanine and perfluorocopper phthalocyanine; porphyrin compounds such as tetrabenzoporphyrin and macrocyclic compounds such as metal salts thereof.
In addition, those described in International Publication No. 2007/126102 pamphlet can be used.

The organic semiconductor functions as any of p-type, n-type, and i-type depending on the type and usage state.
Moreover, it is preferable that the grade of the semiconductor characteristic which an organic semiconductor shows is the same grade as a Cu-III-VI ₂ group semiconductor.

  The organic semiconductor is usually contained in at least one of the layers constituting the solar cell element 6, and the solar cell element 6 absorbs light in the layer containing the semiconductor to generate electricity. ing. A specific configuration of the solar cell element 6 will be described below with an example. However, the solar cell element 6 according to the present invention is not limited to the example described below.

  For example, the organic solar cell element includes at least an active layer between a pair of electrodes. In the solar cell element having such a configuration, light is absorbed in the active layer to generate electricity, and the generated electricity is extracted from the electrode.

-Electrode Also in an organic solar cell element, an electrode is the same as that of a Cu-III-VI group ₂ semiconductor solar cell element.

Active layer The active layer is a layer containing a semiconductor and is a layer that absorbs light and separates charges. This active layer may be composed of only a single layer film or may be composed of two or more laminated films. In the organic solar cell element, an organic semiconductor is used as at least one of the semiconductors, preferably as all.

  The specific configuration of the active layer is arbitrary as long as at least a p-type semiconductor and an n-type semiconductor are contained. For example, an n-type semiconductor and a p-type semiconductor may be contained in separate films, or an n-type semiconductor and a p-type semiconductor may be contained in the same film. In addition, each of the n-type semiconductor and the p-type semiconductor may be used alone or in combination of two or more in any combination and ratio.

  Furthermore, the organic semiconductor is usually present in an aggregated state such as in the form of particles or fibers. At this time, the particle size of the semiconductor is usually 2 nm or more, preferably 5 nm or more, and usually 10 μm or less, preferably 1 μm or less. In the organic solar cell element, it is possible to satisfactorily disperse particles having such a small particle size in the active layer. In the organic solar cell element manufactured by using it, it is possible to disperse particularly well.

A latent pigment refers to precursors having different chemical structures of pigments. By applying an external stimulus such as heating or light irradiation to the latent pigment, the chemical structure of the latent pigment is changed and converted into the pigment.
The latent pigment is preferably excellent in film formability. This is because even if the pigment has poor film formability, the cost during film formation can be reduced by forming the film in the state of a latent pigment and then converting it to a pigment. In particular, in order to be able to apply the coating process, it is preferable that the latent pigment itself can be applied in a liquid state, or the latent pigment can be applied as a solution with high solubility in some solvent. If the suitable range of solubility is mentioned, the solubility with respect to the solvent of a latent pigment is 0.1 weight% or more normally, Preferably it is 0.5 weight% or more, More preferably, it is 1 weight% or more.
Furthermore, it is preferable that the latent pigment can be easily converted into a pigment. In the process of converting the latent pigment to the pigment, what kind of external stimulus is given to the latent pigment is arbitrary, but usually heat treatment, light irradiation, etc. are performed.
Moreover, it is preferable that a latent pigment is converted into a pigment with a high yield through a conversion process. Under the present circumstances, the yield of the pigment obtained by converting from a latent pigment is arbitrary unless the performance of an organic photoelectric conversion element is impaired remarkably. If the suitable range of a yield is mentioned, the yield of the pigment obtained from a latent pigment is so preferable that it is high, and is 90% or more normally, Preferably it is 95% or more, More preferably, it is 99% or more.
An organic semiconductor obtained by converting a latent pigment is a compound having a low solubility in a general solvent. Here, the low solubility in a general solvent means, for example, that the solubility in toluene is usually 1% or less, preferably 0.1% or less.

  In the active layer, it is preferable that the p-type semiconductor and the n-type semiconductor are phase-separated and the active layer has a phase-separated structure. If the active layer has a phase separation structure, carrier separation occurs due to light irradiation, and after holes and electrons are generated, the probability of reaching the electrodes without recombination can be increased. Because it can be expected. Such a phase separation structure can be suitably realized when an organic semiconductor and an inorganic semiconductor are used in combination as semiconductors.

  A phase separation structure is a structure in which materials constituting a phase (for example, semiconductors) are not uniformly mixed at the molecular level, and each material is in an aggregated state, and between the aggregated states. Have an interface. This phase-separated structure can be observed by a method of examining a local structure such as an optical microscope, an electron microscope, or an atomic force microscope (AFM), or by diffracting from an aggregated portion by X-ray diffraction. Can be confirmed.

  The specific configuration of the active layer varies depending on the type of the organic solar cell element. Examples of the configuration of the active layer include a bulk heterojunction type, a stacked type (hetero pn junction type), and a Schottky type.

The bulk heterojunction type includes a p-type semiconductor and an n-type semiconductor in a single active layer. And it has a phase separation structure in which a p-type semiconductor and an n-type semiconductor are phase-separated, carrier separation occurs at the interface of the phase, and positive charges (holes) and negative charges (electrons) in each phase Are separated and transported.
In the bulk heterojunction type active layer, the phase separation structure has an influence on the light absorption process, the exciton diffusion process, the exciton dissociation (carrier separation) process, the carrier transport process, and the like. Therefore, it is considered that good photoelectric conversion efficiency can be realized by optimizing the phase separation structure.

  In the stacked type (hetero pn junction type), the active layer is composed of two or more films, at least one film is formed containing a p-type semiconductor, and the other film contains an n-type semiconductor. Is formed. A phase interface between the p-type semiconductor and the n-type semiconductor is formed at the boundary between the film containing the p-type semiconductor and the film containing the n-type semiconductor, and carrier separation occurs at the phase interface. It is supposed to happen.

  It is also possible to combine a bulk heterojunction type and a laminated type. For example, the active layer is composed of two or more films, and at least one of these films contains both p-type and n-type semiconductors, and the p-type semiconductor and the n-type semiconductor are phase-separated. It is constituted as follows. In this case, carrier separation occurs at both the phase interface formed between the stacked films and the phase interface between the p-type semiconductor and the n-type semiconductor in the film containing both the p-type and n-type semiconductors. It has come to occur. Alternatively, in this case, for example, it is expected that one carrier is blocked between the laminated films to improve the electric extraction efficiency.

  In the Schottky type, a Schottky barrier is formed in the vicinity of an electrode, and carrier separation is performed by an internal electric field in this portion. If an electrode that forms a Schottky barrier is used as the electrode, the structure of the active layer is not limited. As the specific configuration of the active layer in the Schottky type, any of the above-described bulk heterojunction type, stacked type, and a combination type of both can be adopted, and particularly high characteristics (for example, conversion efficiency) are expected. it can.

In the organic solar cell element, at least one kind of organic semiconductor is used for the active layer, but an inorganic substance may be included in addition to this (hereinafter referred to as a hybrid type).
In the hybrid type, the active layer is formed by containing both an inorganic substance and an organic substance. At this time, the inorganic substance and the organic substance contained in the hybrid active layer may have no semiconductor characteristics except that they contain at least one kind of organic semiconductor, but those having semiconductor characteristics ( That is, it is preferable to use an inorganic semiconductor and an organic semiconductor. For example, perylene pigments, quinacridone pigments, phthalocyanine pigments, porphyrin pigments and the like are listed as organic semiconductors used in the hybrid type, and titania and zinc oxide are listed as inorganic semiconductors.

  A specific example of the layer structure of the hybrid type active layer is as follows. In the bulk heterojunction type active layer, when an inorganic substance is used as one of the p-type and n-type semiconductors and an organic substance is used as the other, the p-type is used. And the case where an inorganic substance and an organic substance are used as one or both of the n-type semiconductor and the like. Thereby, an active layer is comprised as a mixed film of an inorganic semiconductor and an organic semiconductor, and improvement in the efficiency of an organic solar cell element can be expected.

[Other matters]
Other layers The Cu-III-VI group ₂ semiconductor solar cell element and organic solar cell element shown in the above example include other layers in addition to the above-described electrode, light absorption layer, buffer layer, and active layer. May be. The positions where other layers are formed are arbitrary as long as the power generation of the solar cell element 6 is not hindered. An example of such a layer is an electrode interface layer.

  The electrode interface layer is a layer provided for improving electrical characteristics between the light absorbing layer, the buffer layer or the active layer and the electrode. Normally, a layer (p-type semiconductor layer) that blocks electrons and conducts only holes is formed between the electrode that collects holes and the light absorption layer, buffer layer, or active layer, and collects electrons. A layer that blocks holes and conducts only electrons (n-type semiconductor layer) is formed between the electrode to be formed and the light absorption layer, buffer layer, or active layer.

As a material of the p-type semiconductor layer (p-type semiconductor), a material that can efficiently transport generated holes to the positive electrode is preferable. For this purpose, the p-type semiconductor has a high hole mobility, a high conductivity, a small hole injection barrier with the positive electrode, a light absorption layer, a buffer layer, or an active layer to a p-type semiconductor layer. It is preferable to have properties such as a small hole-injection barrier.
Furthermore, when taking light into the light absorption layer or the active layer through the p-type semiconductor layer, it is preferable to use a transparent material as the p-type semiconductor. Usually, visible light will be taken into the light absorption layer or active layer among the light, and as a transparent p-type semiconductor, the transmittance of visible light transmitted through the p-type semiconductor layer is usually 60% or more, Among them, it is preferable to use those that are 80% or more. In order to realize this, a material that does not absorb visible light is used, or the p-type semiconductor layer may be formed as a thin film that is thin enough to satisfy the transmittance even if there is absorption.
Furthermore, in order to reduce the manufacturing cost and increase the area of the solar cell element 6, it is preferable to use an organic semiconductor as the p-type semiconductor and form the p-type semiconductor layer as a p-type organic semiconductor layer.

  From this point of view, a suitable example of a p-type semiconductor includes a porphyrin compound or a phthalocyanine compound. These compounds may have a central metal or may be metal-free. Specific examples thereof include 29H, 31H-phthalocyanine, copper (II) phthalocyanine, zinc (II) phthalocyanine, titanium phthalocyanine oxide, copper (II) 4,4 ′, 4 ″, 4 ′ ″-tetraaza-29H. , 31H-phthalocyanine and the like; and porphyrin compounds such as tetrabenzoporphyrin, tetrabenzocopper porphyrin, and tetrabenzozinc porphyrin;

Examples of preferable p-type semiconductors other than porphyrin compounds and phthalocyanine compounds include a system in which a dopant is mixed with a hole transporting polymer. In this case, examples of the hole transporting polymer include poly (ethylenedioxythiophene), polythiophene, polyaniline, polypyrrole, and the like. On the other hand, examples of the dopant include iodine; acids such as poly (styrene sulfonic acid) and camphor sulfonic acid; Lewis acids such as PF ₅ , AsF ₅ and FeCl ₃ ; In addition, a p-type semiconductor may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. Moreover, the semiconductor illustrated here can also be contained in a light absorption layer, a buffer layer, or an active layer.

Although there is no restriction | limiting in the thickness of a p-type semiconductor layer, For example, in an organic solar cell element, it is preferable that it is normally 3 nm or more, especially 10 nm or more, and usually 200 nm or less, especially 100 nm or less. Increasing the thickness of the p-type semiconductor layer tends to increase the uniformity of the film, and decreasing the thickness of the p-type semiconductor layer tends to improve the transmittance and decrease the series resistance.
For example, in a Cu-III-VI group ₂ semiconductor solar cell element, it is usually 0.5 μm or more, preferably 1 μm or more, and usually 10 μm or less, preferably 5 μm or less. When the p-type semiconductor layer is thinned, the power generation efficiency tends to decrease. When the p-type semiconductor layer is thickened, cracks are easily generated when the p-type semiconductor layer is bent, or the Mo layer is easily separated.

On the other hand, the role required for the n-type semiconductor layer is to block holes separated from the light absorption layer or the active layer and transport only electrons to the negative electrode. As a material of the n-type semiconductor layer (n-type semiconductor), a material that can efficiently transport the generated electrons to the negative electrode is preferable. For this purpose, the n-type semiconductor has high electron mobility, high conductivity, a small electron injection barrier between the negative electrode, and electrons from the light absorption layer, buffer layer, or active layer to the n-type semiconductor. It is preferable to have properties such as a small injection wall.
Furthermore, when taking light into the light absorption layer or the active layer through the n-type semiconductor layer, it is preferable to use a transparent material as the n-type semiconductor. Usually, visible light will be taken into the light absorption layer or active layer among the light, and as a transparent n-type semiconductor, the transmittance of visible light transmitted through the n-type semiconductor layer is usually 60% or more, Among them, it is preferable to use those that are 80% or more. In order to realize this, a material that does not absorb visible light may be used, or the n-type semiconductor layer may be formed as a thin film that is thin enough to satisfy the transmittance even if there is absorption.
The role required for the n-type semiconductor layer is also to prevent the exciton (exciton) generated by absorbing light in the light absorption layer or active layer from being quenched by the negative electrode. For this purpose, the n-type semiconductor preferably has an optical gap larger than that of the electron donor and the electron acceptor.

From this point of view, preferable examples of n-type semiconductors include organic compounds exhibiting electron transport properties such as phenanthroline derivatives and silole derivatives; inorganic semiconductors such as TiO ₂ . In addition, an n-type semiconductor may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios. Moreover, the semiconductor illustrated here can also be contained in a light absorption layer, a buffer layer, or an active layer.

  Although there is no restriction | limiting in the thickness of an n-type semiconductor layer, For example, in an organic solar cell element, it is 2 nm or more normally, Especially 5 nm or more, Furthermore, it is preferable to set it as 200 nm or less especially 100 nm or less. By forming the n-type semiconductor layer in such a thickness range, when light incident from the positive electrode is transmitted without being absorbed by the light absorption layer or active layer, it is reflected by the negative electrode and is again reflected by the light absorption layer or active layer. It is possible to make use of the optical interference effect by returning to step (b).

-Connection between solar cell elements Only one solar cell element 6 may be provided for each thin film solar cell 100, but usually two or more solar cell elements 6 are provided. The specific number of solar cell elements 6 may be set arbitrarily. When a plurality of solar cell elements 6 are provided, the solar cell elements 6 are often arranged in an array.

  When a plurality of solar cell elements 6 are provided, the solar cell elements 6 are usually electrically connected to each other, and electricity generated from the connected group of solar cell elements 6 is taken out from a terminal (not shown). At this time, the solar cell elements are usually connected in series in order to increase the voltage.

  Thus, when connecting the solar cell elements 6, it is preferable that the distance between the solar cell elements 6 is small, and the clearance between the solar cell element 6 and the solar cell element 6 is preferably narrow. This is because the light receiving area of the solar cell element 6 is widened to increase the amount of light received, and the amount of power generated by the thin film solar cell 100 is increased.

[Encapsulant 7]
The sealing material 7 is a film similar to the sealing material 5 described above, and the same material as the sealing material 7 can be used in the same manner except that the arrangement position is different.
Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[Getter material film 8]
The getter material film 8 is the same film as the getter material film 4 described above, and the same material as the getter material film 4 can be used as necessary except that the arrangement position is different.
Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used. It is also possible to use a film containing more water or oxygen absorbent than the getter material film 4. Examples of such absorbents include CaO, BaO, Zr-Al-BaO as moisture absorbents, and activated carbon, molecular sieves and the like as oxygen absorbents.

[Gas barrier film 9]
The gas barrier film 9 is the same film as the gas barrier film 3 described above, and the same material as the gas barrier film 9 can be used as necessary, except for the arrangement position.
Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[Backsheet 10]
The back sheet 10 is the same film as the weather-resistant protective film 1 described above, and the same material as the weather-resistant protective film 1 can be used in the same manner except that the arrangement position is different. Further, if the back sheet 10 is difficult to permeate water and oxygen, the back sheet 10 can function as a gas barrier layer.
Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used. For this reason, it is particularly preferable to use the following (i) to (iv) as the backsheet 10.

(I) As the back sheet 10, various resin films or sheets excellent in strength and excellent in weather resistance, heat resistance, water resistance, and light resistance can be used. For example, polyethylene resin, polypropylene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resin, fluorine Resins, poly (meth) acrylic resins, polycarbonate resins, polyester resins such as polyethylene terephthalate or polyethylene naphthalate, polyamide resins such as various nylons, polyimide resins, polyamideimide resins, polyaryl phthalate resins Sheet of various resins such as silicone resin, polysulfone resin, polyphenylene sulfide resin, polyethersulfone resin, polyurethane resin, acetal resin, cellulose resin, etc. It is possible to use. Among these resin sheets, it is preferable to use a fluorine resin, a cyclic polyolefin resin, a polycarbonate resin, a poly (meth) acrylic resin, a polyamide resin, or a polyester resin sheet. In addition, these may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

(Ii) As the back sheet 10, a metal thin film can also be used. For example, corrosion-resistant aluminum metal foil, stainless steel thin film, and the like can be mentioned. In addition, the said metal may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

(Iii) As the back sheet 10, for example, a highly waterproof sheet in which a fluorine resin film is bonded to both surfaces of an aluminum foil may be used. Examples of the fluorine resin include ethylene monofluoride (trade name: Tedlar, manufactured by DuPont), polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and ethylene or propylene (ETFE), and vinylidene fluoride resin. (PVDF), vinyl fluoride resin (PVF) and the like. In addition, 1 type may be used for fluororesin and it may use 2 or more types together by arbitrary combinations and a ratio.

(Iv) As the back sheet 10, for example, an inorganic oxide vapor-deposited film is provided on one side or both sides of the base film, and further, on both sides of the base film provided with the inorganic oxide vapor-deposited film, You may use what laminated | stacked the heat resistant polypropylene resin film. Usually, when a polypropylene resin film is laminated on the base film, the lamination is performed by laminating with a laminating adhesive. By providing an inorganic oxide vapor-deposited film, it can be used as a back sheet 10 having excellent moisture resistance that prevents intrusion of moisture, oxygen and the like.

・ Base film Basically, the base film is excellent in close adhesion with inorganic oxide vapor deposition film, etc., excellent in strength, weather resistance, heat resistance, water resistance, and light resistance. Resin films can be used. For example, polyethylene resin, polypropylene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resin, fluorine Resin, poly (meth) acrylic resin, polycarbonate resin, polyester resin such as polyethylene terephthalate or polyethylene naphthalate, various polyamide resins such as nylon, polyimide resin, polyamideimide resin, polyaryl phthalate resin Silicone resin, polysulfone resin, polyphenylene sulfide resin, polyethersulfone resin, polyurethane resin, acetal resin, cellulose resin, etc. It is possible to use. Among these, it is preferable to use a film of a fluorine resin, a cyclic polyolefin resin, a polycarbonate resin, a poly (meth) acrylic resin, a polyamide resin, or a polyester resin.

  Among the various resin films described above, for example, a film of a fluorine resin such as polytetrafluoroethylene (PTFE), vinylidene fluoride resin (PVDF), or vinyl fluoride resin (PVF) is used. More preferably it is used. Further, among these fluororesin films, in particular, a fluororesin film (PVF); a fluororesin film made of a copolymer of tetrafluoroethylene and ethylene or propylene (ETFE) is particularly preferable from the viewpoint of strength and the like. preferable. In addition, the said resin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  Of the various resin films as described above, it is more preferable to use a film of a cyclic polyolefin resin such as cyclopentadiene and a derivative thereof, cyclohexadiene and a derivative thereof.

  The film thickness of the base film is usually 12 μm or more, preferably 20 μm or more, and is usually 300 μm or less, preferably 200 μm or less.

-Vapor deposition film of an inorganic oxide As a vapor deposition film of an inorganic oxide, basically any thin film on which a metal oxide is deposited can be used. For example, a deposited film of an oxide of silicon (Si) or aluminum (Al) can be used. At this time, for example, SiO _x (x = 1.0 to 2.0) can be used as silicon oxide, and for example, AlO _x (x = 0.5 to 1.5) can be used as aluminum oxide. .
In addition, the kind of metal and inorganic oxide to be used may be 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  The film thickness of the inorganic oxide vapor deposition film is usually 50 mm or more, preferably 100 mm or more, and is usually 4000 mm or less, preferably 1000 mm or less.

  As a method for forming the deposited film, a chemical vapor deposition method (chemical vapor deposition method, CVD method) such as a plasma chemical vapor deposition method, a thermal chemical vapor deposition method, or a photochemical vapor deposition method can be used. As a specific example, on one surface of the base film, a monomer gas for vapor deposition such as an organosilicon compound is used as a raw material, an inert gas such as argon gas or helium gas is used as a carrier gas, and oxygen is supplied. An oxygen oxide vapor or the like can be used as a gas, and a vapor deposition film of an inorganic oxide such as silicon oxide can be formed using a low temperature plasma chemical vapor deposition method using a low temperature plasma generator or the like.

-Polypropylene resin film As a polypropylene resin, the homopolymer of propylene; for example, the copolymer of propylene and another monomer (for example, alpha olefin etc.) can be used. Moreover, an isotactic polymer can also be used as a polypropylene resin.

The melting point of the polypropylene resin is usually from 164 ° C to 170 ° C, the specific gravity is usually from 0.90 to 0.91, and the molecular weight is usually from 100,000 to 200,000.
Polypropylene resins are largely controlled by their crystallinity, but high isotactic polymers have excellent tensile strength and impact strength, good heat resistance and bending fatigue strength, and workability. Is very good.

-Adhesive When laminating a polypropylene resin film on a base film, an adhesive for laminating is usually used. Thereby, a base film and a polypropylene resin film are laminated | stacked via the adhesive bond layer for lamination.
Examples of the adhesive constituting the adhesive layer for laminating include, for example, polyvinyl acetate adhesive, polyacrylate adhesive, cyanoacrylate adhesive, ethylene copolymer adhesive, cellulose adhesive, and polyester adhesive. Adhesives, polyamide adhesives, polyimide adhesives, amino resin adhesives, phenol resin adhesives, epoxy adhesives, polyurethane adhesives, reactive (meth) acrylic adhesives, silicone adhesives, etc. Is mentioned. In addition, 1 type may be used for an adhesive agent and it may use 2 or more types together by arbitrary combinations and a ratio.

The composition system of the adhesive may be any composition form such as an aqueous type, a solution type, an emulsion type, and a dispersion type. Moreover, the form may be any form such as a film / sheet form, a powder form, or a solid form. Furthermore, the bonding mechanism may be any form such as a chemical reaction type, a solvent volatilization type, a heat melting type, and a hot pressure type.
The adhesive can be applied by a coating method such as a roll coating method, a gravure roll coating method, a kiss coating method, or the like, or a printing method. As the amount of ^{coating, 0.1g / m 2 ~10g / m} 2 is desirable in the dry state.

[Sealant 11]
The sealing material 11 includes the weatherproof protective film 1, the ultraviolet cut film 2, the gas barrier film 3, the getter material film 4, the sealing material 5, the sealing material 7, the getter material film 8, the gas barrier film 9, and the back sheet 10. It is a member that seals the edge so that moisture and oxygen do not enter the space covered with these films.

The degree of moisture capacity required for the sealing member 11 is preferably water vapor transmission rate per day unit area (1 m ²⁾ is not more than ^{0.1g / m 2 / day, 0.05g} / m 2 / More preferably, it is not more than day. Conventionally, since it has been difficult to mount the sealing material 11 having such a high moisture-proof capability, it is possible to realize a solar cell including an excellent solar cell element such as a compound semiconductor solar cell element and an organic solar cell element. Although it was difficult, the implementation of the thin-film solar cell 100 utilizing the excellent properties of the compound semiconductor solar cell element and the organic solar cell element is facilitated by applying such a sealing material 11.

  Furthermore, since the thin film solar cell 100 is often heated by receiving light, it is preferable that the sealing material 11 also has heat resistance. From this viewpoint, the melting point of the constituent material of the sealing material 11 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 250 ° C. or lower, preferably 200 ° C. or lower, more preferably 180 ° C. or lower. If the melting point is too low, the sealing material 11 may melt when the thin film solar cell 100 is used.

Examples of the material constituting the sealing material 11 include polymers such as a fluorine resin, a silicone resin, and an acrylic resin.
In addition, the sealing material 11 may be formed with 1 type of material, and may be formed with 2 or more types of materials.

  The sealing material 11 is provided at a position where at least the edges of the gas barrier films 3 and 9 can be sealed. Thereby, the space surrounded by at least the gas barrier films 3 and 9 and the sealing material 11 can be sealed, and moisture and oxygen can be prevented from entering the space.

Although there is no restriction | limiting in the method of forming this sealing material 11, For example, it can form by inject | pouring material between the weather-resistant protective film 1 and the back sheet | seat 10. FIG. Specific examples of the forming method include the following methods.
That is, for example, while the curing of the sealing material 5 proceeds, the semi-cured thin film solar cell 100 is taken out from the laminating apparatus, and is the outer peripheral portion of the solar cell element 6, which is the weatherproof protective sheet 1 and the back sheet 10. A liquid polymer may be injected into a portion between the two and the polymer may be cured together with the sealing material 5. Further, after the sealing material 5 has been cured, it may be taken out from the laminating apparatus and cured alone. The temperature range for crosslinking and curing the polymer is usually 130 ° C. or higher, preferably 140 ° C. or higher, and is usually 180 ° C. or lower, preferably 170 ° C. or lower.

[Dimensions]
The thin film solar cell 100 of the present embodiment is usually a thin film member. By forming the thin film solar cell 100 as a film-like member in this way, the thin film solar cell 100 can be easily installed in building materials, automobiles, interiors, and the like. The thin-film solar cell 100 is light and difficult to break, and thus a highly safe solar cell can be obtained and can be applied to a curved surface, so that it can be used for more applications. Since it is thin and light, it is preferable in terms of distribution such as transportation and storage. Furthermore, since it is in the form of a film, it can be manufactured in a roll-to-roll manner, and a significant cost cut can be achieved.
Although there is no restriction | limiting in the specific dimension of the thin film solar cell 100, The thickness is 300 micrometers or more normally, Preferably it is 500 micrometers or more, More preferably, it is 700 micrometers or more, Usually, 3000 micrometers or less, Preferably it is 2000 micrometers or less, More preferably. It is 1500 micrometers or less.

[Production method]
Although there is no restriction | limiting in the manufacturing method of the thin film solar cell 100 of this embodiment, For example, between the weather-resistant protective film 1 and the back sheet | seat 10, the 1 or 2 or more solar cell element 6 was connected in series or in parallel. The product can be manufactured by laminating with a general vacuum laminating apparatus together with the ultraviolet cut film 2, the gas barrier films 3, 9, the getter material films 4, 8 and the sealing materials 5, 7. Under the present circumstances, heating temperature is 130 degreeC or more normally, Preferably it is 140 degreeC or more, and is 180 degrees C or less normally, Preferably it is 170 degrees C or less. The heating time is usually 10 minutes or longer, preferably 20 minutes or longer, usually 100 minutes or shorter, preferably 90 minutes or shorter. The pressure is usually 0.001 MPa or more, preferably 0.01 MPa or more, and usually 0.2 MPa or less, preferably 0.1 MPa or less. By setting the pressure within this range, sealing can be performed reliably, and the sealing materials 5 and 7 from the end can be prevented from protruding or reduced in film thickness due to over-pressurization, thereby ensuring dimensional stability.

[advantage]
Since the thin-film solar cell 100 of the present embodiment is configured as described above, when the light receiving surface is irradiated with light, the solar cell element 6 that has absorbed the light generates power.
At this time, the thin-film solar cell 100 of the present embodiment can be used even in an environment with high humidity because the solar cell element 6 can be protected from moisture by the gas barrier films 3 and 9 and the sealing material 11. Moreover, since the solar cell of the present invention includes the ultraviolet cut film 2, the gas barrier films 3, 9 and the solar cell element 6 are not deteriorated by the ultraviolet rays, and power can be generated with high efficiency over a long period of time. As described above, according to the present invention, a practical solar cell resistant to moisture and ultraviolet rays can be newly realized.

The thin-film solar cell 100 of this embodiment, the compound semiconductor type solar cell element such as a Cu-III-VI ₂ group semiconductor solar cell element 6, and / or, if it has an organic solar cell device, high power generation Power can be generated with efficiency.
Furthermore, since the thin film solar cell 100 of this embodiment is provided with the getter material films 4 and 8, the solar cell element 6 can be more reliably protected from moisture and oxygen.
Moreover, since the thin film solar cell 100 of this embodiment is equipped with the weather-resistant protective film 1 and the back sheet | seat 10, it has tolerance with respect to the change of a weather, and can generate electric power stably over a longer period.
Furthermore, since the thin film solar cell 100 of this embodiment is equipped with the sealing materials 5 and 7, intensity | strength is high and handleability is favorable.

  Furthermore, the thin-film solar cell 100 of the present embodiment can secure a sufficient amount of power generation even when exposed to the outside for a long period of time, and has a sufficient flexibility and strength so that the curved surface that could not be installed. Can be installed.

[Usage]
There is no restriction | limiting in the use of the thin film solar cell 100 mentioned above, It is arbitrary. For example, as schematically shown in FIG. 2, a solar cell unit 13 in which a thin film solar cell 100 is provided on a certain base material 12 is prepared and used at a place of use. As a specific example, when a building material plate is used as the base material 12, a thin film solar cell 100 is provided on the surface of the plate material to produce a solar cell panel as the solar cell unit 13, and this solar cell panel is attached to the outer wall of the building. It can be installed and used.

  The substrate 12 is a support member that supports the solar cell element 6. Examples of the material for forming the substrate 12 include inorganic materials such as glass, sapphire, and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluorine. Organic materials such as resin film, vinyl chloride, polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene; paper materials such as paper and synthetic paper; metals such as stainless steel, titanium, and aluminum In addition, a composite material such as a material whose surface is coated or laminated in order to impart insulating properties may be used. In addition, 1 type may be used for the material of a base material, and 2 or more types may be used together by arbitrary combinations and a ratio. Moreover, carbon fiber may be included in these organic materials or paper materials to reinforce the mechanical strength.

  Examples of fields to which the thin film solar cell of the present invention is applied include solar cells for building materials, solar cells for automobiles, solar cells for interiors, solar cells for railways, solar cells for ships, solar cells for airplanes, solar cells for spacecraft. It is suitable for use in batteries, solar cells for home appliances, solar cells for mobile phones, solar cells for toys, and the like. Specific examples include the following.

1. Building use 1.1 Solar cell as house roofing material When a roof plate or the like is used as a base material, a thin-film solar cell is provided on the surface of this plate material to produce a solar cell panel as a solar cell unit. Just install on the roof of the house. Moreover, a roof tile can also be used directly as a base material. The solar cell of the present invention is suitable because it can be brought into close contact with the roof tiles by taking advantage of its flexibility.

1.2 Rooftop Can be installed on the rooftop of a building. A solar cell unit in which a thin film solar cell is provided on a base material can be prepared and installed on the roof of a building. At this time, it is desirable to use a waterproof sheet together with the base material to have a waterproof action. Furthermore, taking advantage of the property that the thin film solar cell of the present invention has flexibility, it can be brought into close contact with a roof that is not flat, for example, a folded roof. In this case, it is desirable to use a waterproof sheet in combination.

1.3 Toplight The thin-film solar cell of the present invention can also be used as an exterior at the entrance or at the atrium. Curves are often used for entrances and the like that have undergone some design processing, and in such a case, the flexibility of the thin film solar cell of the present invention is utilized. In addition, there is a case of see-through in an entrance or the like. In such a case, the green color of the organic solar cell is suitable because a design aesthetic can be obtained in an era when environmental measures are regarded as important.

1.4 Wall When a building material plate is used as the base material, a thin film solar cell is provided on the surface of the plate material to produce a solar cell panel as a solar cell unit, and this solar cell panel is installed on the outer wall of the building. Use it. It can also be installed on curtain walls. In addition, it can be attached to a spandrel or a vertical.
In this case, although there is no restriction | limiting in the shape of a base material, Usually, a board | plate material is used. Moreover, what is necessary is just to set the material of a base material, a dimension, etc. arbitrarily according to the use environment. As an example of such a substrate, Alpolic (registered trademark; manufactured by Mitsubishi Plastics) and the like can be mentioned.

1.5 windows It can also be used for see-through windows. The green color of the organic solar cell is preferable because a design aesthetic can be obtained in an era when environmental measures are important.

1.6 Others Can be used for eaves, louvers, handrails, etc. as other architectural exteriors. Even in such a case, the flexibility of the thin film solar cell of the present invention is suitable for these applications.

2. Interior The thin film solar cell of this invention can also be attached to the slat of a blind. Since the thin-film solar cell of the present invention is lightweight and rich in flexibility, such a use is possible. Further, the contents window can be used by utilizing the characteristic that the organic solar cell element is see-through.

3. Vegetable factories Although the number of plant factories that use illumination light such as fluorescent lights is increasing, the current situation is that it is difficult to reduce the cultivation cost due to the electricity costs for lighting and replacement costs of light sources. Then, the thin film solar cell of this invention can be installed in a vegetable factory, and the illumination system combined with LED or the fluorescent lamp can be produced.
At this time, it is preferable to use an illumination system that combines an LED having a longer life than a fluorescent lamp and the solar cell of the present invention, because the cost required for illumination can be reduced by about 30% compared to the current situation.
Moreover, the solar cell of this invention can also be used for the roof and side wall of the reefer container (reefer container) which conveys vegetables etc. at fixed temperature.

4). Road Material / Civil Engineering The thin film solar cell of the present invention can be used for an outer wall of a parking lot, a sound insulation wall of an expressway, an outer wall of a water purification plant, and the like.

5). Automotive The thin film solar cell of the present invention can be used on the surfaces of automobile bonnets, roofs, trunk lids, doors, front fenders, rear fenders, pillars, bumpers, rearview mirrors and the like. The obtained electric power can be supplied to any of a traveling motor, a motor driving battery, an electrical component, and an electrical component battery. By providing the power generation status in the solar cell panel and the control means for selecting according to the power usage status in the motor for driving, the battery for driving the motor, the electrical equipment, and the battery for electrical equipment, the obtained power is Can be used properly and efficiently

In the above case, the shape of the substrate 12 is not limited, but a plate material is usually used. Moreover, what is necessary is just to set the material of the base material 12, a dimension, etc. arbitrarily according to the use environment.
Examples of such a substrate 12 include Alpolic (registered trademark; manufactured by Mitsubishi Plastics).

[Others]
Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiments and examples, and can be implemented with any modifications without departing from the spirit of the present invention.

For example, the thin-film solar cell 100 includes the above-described weather-resistant protective film 1, ultraviolet cut film 2, gas barrier films 3 and 9, getter material films 4 and 8, solar cell element 6, sealing materials 5 and 7, and backsheet 10. Further, films and members other than the sealing material 11 may be provided. Moreover, as long as it is a range which does not deviate from the summary of this invention, you may make it not provide a part of film mentioned above.
Further, for example, the weather-resistant protective film 1, the ultraviolet cut film 2, the gas barrier films 3 and 9, the getter material films 4 and 8, the solar cell element 6, the sealing materials 5 and 7, the back sheet 10 and the sealing material 11 are arranged. The installation position can be arbitrarily changed without departing from the gist of the present invention.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and can be arbitrarily modified without departing from the gist of the present invention.

[Example 1]
<Film structure of thin film solar cell>
The following solar cell element and film are used.

Solar cell element A Mo layer is formed on a SUS substrate, a Cu (In, Ga) Se ₂ layer is formed thereon, a CdS buffer layer is formed thereon, and a ZnO: Al window layer is formed thereon. A solar cell element having

-Weather-resistant protective film As a weather-resistant protective film, a 50-micrometer-thick unstretched ethylene-tetraethylene copolymer fluororesin film ("Aflex" manufactured by Asahi Glass Co., Ltd.).

UV cut film A commercially available UV cut film (99% cut wavelength 370 nm).

· The gas barrier film PET film with a gas barrier film having a layer of SiO _x, water vapor transmission rate ^{1 × 10 -4 g / m 2} / day.

Sealing material EVA film having a thickness of 100 μm (trade name: VS sheet, Kurabo Industries).

Back sheet A 120 μm-thick white film (DuPont product name: Tedra-PVF) in which an aluminum foil is sandwiched with polyvinyl fluoride (PVF).

<Production of thin-film solar power>
After the above film is laminated in the order of a weather-resistant protective film, an ultraviolet cut film, a gas barrier film, a sealing material, a solar cell element, a sealing material and a back sheet, and after vacuum heating and pressure bonding under a predetermined condition by a laminating apparatus Then, the sealing material is taken out from the laminating apparatus in a semi-cured state, and then a sealing material is injected between the weather resistant protective film and the back sheet. Thereafter, the main cross-linking of EVA at 150 ° C. for 60 minutes and the cross-linking / curing of the fluororesin and the end face sealing material are simultaneously performed to produce a thin film solar cell.

<Evaluation>
The FF value (curve factor) under AM1.5 (100 mW / cm ² ) light irradiation is measured. Then, this thin film solar cell is hold | maintained on 85 degreeC and 85% RH conditions for 1000 hours, and the curve FF value under AM1.5 (100 mW / cm < ² >) light irradiation is measured again.

[Comparative Example 1]
A thin film solar cell is produced under the same film and under the same conditions except that the gas barrier film is not used in Example 1.
When the same evaluation as in Example 1 is performed, the FF value of the thin-film solar cell of Comparative Example 1 after holding for 1000 hours under the conditions of 85 ° C. and 85% RH is about 80% of the corresponding FF value in Example 1. Become.

  INDUSTRIAL APPLICABILITY The present invention can be widely applied to the fields related to solar cells, and in particular, solar cells for building materials, automobile solar cells, interior solar cells, railway solar cells, marine solar cells, airplane solar cells, and spacecraft solar cells. It is suitable for use in solar cells for home appliances, solar cells for mobile phones, solar cells for toys, and the like.

It is sectional drawing which shows typically the structure of the solar cell as one Embodiment of this invention. It is sectional drawing which shows typically the structure of the solar cell unit as one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Weatherproof protective film 2 Ultraviolet cut film 3,9 Gas barrier film 4,8 Getter material film 5,7 Sealing material 6 Solar cell element 10 Back sheet 11 Sealing material 12 Base material 13 Solar cell unit 100 Thin film solar cell

Claims (8)

A solar cell element that generates light by receiving light; and
A gas barrier film covering the solar cell element;
A thin-film solar cell comprising: an ultraviolet cut film that covers a light-receiving surface of the solar cell element.   The thin film solar cell according to claim 1, further comprising a getter material film that absorbs moisture and / or oxygen between the solar cell element and the gas barrier film.   The thin-film solar cell according to claim 1, further comprising a weather-resistant protective film that covers a light-receiving surface of the solar cell element.   The thin film solar cell according to any one of claims 1 to 3, further comprising a sealing material that seals an edge of the gas barrier film.   The thin film solar cell according to claim 1, further comprising a back sheet.   The thin film solar cell according to any one of claims 1 to 5, wherein the solar cell element is a compound semiconductor solar cell element or an organic solar cell element.   A solar cell unit comprising: a base material; and the thin-film solar battery according to claim 1 provided on the base material.   A solar cell structure comprising: an article; and the thin-film solar battery according to claim 1 provided on the article.

Images