JPH07321365A - Thin-film solar battery - Google Patents

Abstract

PURPOSE:To prevent the influence of moisture upon a solar battery by providing a water catching layer in the inner surface side of at least one moisture-proof film of two sheets of the moisture-proof films of a solar battery held therebetween. CONSTITUTION:Common ethylene-vinyl acetate copolymer films for bonding agent layers 61, 62 and common polyamide for a water catching layer 8 are laminated on both sides of a solar battery cell. Further, thereon, the bonding agent layers 61, 62 using an EVA film and moisture-proof films 71, 72 using polyphenylene sulphite of which one side is roughened are laminated to form a solar battery. When the solar battery is used outdoors and exposed to rainwater, gaseous moisture in air is caught before it enters into the solar battery through the surface of the moisture-proof films and the combined surface of the end of laminates, so that the influence of moisture upon a solar battery main body may be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film solar cell using a flexible insulating substrate.

[0002]

2. Description of the Related Art Solar cells have been attracting attention as a clean energy source, and their technological progress has been remarkable. In particular, since a photoelectric conversion layer mainly composed of amorphous silicon can be easily formed into a large area and is inexpensive, a thin-film solar cell using it is highly expected. Conventional solar cells used glass substrates, but they are thick and heavy,
There is an increasing demand for thinner and lighter products because of their fragility and improved workability by applying them to outdoor roofs. To meet these demands, a flexible type thin film solar cell using a flexible plastic film and a thin film metal film as a substrate is being put into practical use. Such flexible type solar cells are
For long-term use for 5 years, a moisture-proof film is laminated on both front and back sides of the solar cell via adhesive layers to prevent moisture from entering. FIG. 2 shows a cross-sectional structure of such a flexible solar cell, which comprises a flexible plastic film substrate 1 on one surface of which a first electrode layer 2 made of metal, an amorphous semiconductor layer 3 having a pin junction, ITO, etc. The transparent second electrode layer 4 is laminated, and the third electrode layer 5 described in, for example, Japanese Patent Application No. 5-67976 is formed on the other surface side, and the through hole opened in the substrate 1 is formed. Is connected to the first electrode layer 2 or the second electrode layer 4 through. The solar cell having such a structure includes a transparent moisture-proof film 71 having a transparent adhesive layer 61 on the second electrode layer and a moisture-proof film 72 having an adhesive layer 62 on the third electrode layer 5. It is sandwiched.

[0003]

By the way, the solar cell by such a conventional method can prevent the invasion of water to some extent, but it is not practically sufficient, and further improvement is desired. As the moisture that enters, it is thought that outdoor rainwater and gaseous moisture in the air are considered. Factors that reduce the efficiency of the solar cell by invading through the moisture-proof film surface and the mating surface of the laminate edge due to long-term outdoor use. It was.

The present invention has been made in view of the above problems, and an object thereof is to provide a thin film solar cell having improved moisture resistance and excellent weather resistance.

[0005]

In order to achieve the above-mentioned object, the present invention is to laminate at least a first electrode layer, a photoelectric conversion semiconductor layer, a transparent second electrode layer on a flexible substrate,
A thin-film solar cell sandwiched by two moisture-proof films is provided with a water catching layer on the inner surface side of at least one moisture-proof film. It is effective that the water capturing layer is made of a polyamide resin. Then, it is effective that both surfaces of the water trapping layer are in contact with the adhesive. In that case, it is preferable that the surface on the inner surface side of the water trapping layer which is in contact with the adhesive is roughened.

[0006]

By providing a moisture-trapping layer made of, for example, a polyamide resin on the inside of the moisture-proof film, the moisture exposed to rainwater during outdoor use and the gaseous moisture in the air are brought into contact with the surface of the moisture-proof film and the edge of the laminate. Water entering through the surface is trapped before reaching the solar cells,
That is, it can play the role of a "reservoir" and prevent the influence of water on the solar cell body.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawing in which the same reference numerals are given to the same parts as in FIG. An insulating film or a metal film can be used as the flexible substrate. The film-like insulating substrate is required to have heat resistance because the electrode layer and the amorphous semiconductor layer are formed thereon at about 200 ° C. Therefore, as a plastic film having heat resistance, polyimide,
Polyether imide, polysulfone, polyether sulfone, polyphenylene sulfand, para aramid,
Examples include polyetherketone or fluorine-based films, but polyimide, para-aramid, and fluorine-based films are particularly preferable. The metal film has no problem in terms of heat resistance if foil such as stainless steel, nickel, or copper is used, and it can be used as it is as a conductive substrate that also serves as the first electrode layer, or by applying a heat resistant insulating film on the surface. It can also be used as an insulating substrate. The solar cell module of the first embodiment of the present invention has the cross-sectional structure shown in FIG. 1, a polyimide film (manufactured by Toray DuPont, trade name: Kapton) is used as the insulating film substrate 1, and the first electrode layer 2 is used. Is an Ag film, a nip junction film is an amorphous semiconductor layer 3, an ITO film is a transparent second electrode layer 4, and an Ag film is a third electrode layer 5 on the back side of the insulating substrate 1 by a predetermined device. did. A common ethylene-vinyl acetate copolymer (EVA) film (Mitsui Chemicals, Inc., trade name: Everex) as the adhesive layers 61 and 62 on both sides of this solar cell, and a common polyamide film as the water catching layer 8 (Nylon-6 film) was laminated at a temperature of 130 ° C. for 15 minutes under vacuum heating and pressurization.
The surface of the polyamide film on the EVA film side was roughened by plasma treatment to improve the adhesive. further,
An adhesive layer 6 using an EVA film from above as well
Moisture-proof films 71 and 72 using 1, 62 and polyphenylene sulfide (Toray Co., Ltd., trade name: Trenina) with one surface roughened are laminated at a temperature of 130 ° C. for 15 minutes under vacuum heating and pressurization to form a solar cell module. It was made.
A film of a polyamide resin such as nylon-6, nylon-66 or nylon-6-66-6 / 10 copolymer can be used for the water-trapping layer 8, and a nylon-6 film is preferable. Further, one surface is roughened or an adhesive layer is laminated in advance.
Otherwise, the adhesion with the adhesive layer on the solar cell side will be poor, and in the worst case, phenomena such as peeling will occur, making it impossible to manufacture the solar cell module. Needless to say, it is preferable that the water trapping layer 8 is translucent because it is inserted also on the light incident side.

As the moisture-proof film 71 on the light incident side, a transparent plastic film having a low moisture permeability is used. Fluorine-based materials, polymethylmethacrylate,
Examples thereof include films of polyarylate, polyethylene naphthalate, polysulfone, polyether sulfone, polyvinyl chloride, polycarbonate, polyphenylene sulfide, and the like. Further, the moisture-proof film 72 on the side opposite to the light incident side does not necessarily have to be transparent. For example, in addition to the above film, a metal foil of aluminum or the like is sandwiched with a plastic film. Even if the rate is high,
It is possible to use a metal foil sandwiched between plastic films, which shields moisture from entering.

The materials used for the adhesive layers 61 and 62 are polyvinyl alcohol, polyvinyl butyral, polyolefin-based ethylene-vinyl acetate copolymer (EVA),
Examples thereof include vinyl chloride copolymer, propylene copolymer, acrylonitrile copolymer and the like. The light incident side adhesive layer 61 is preferably transparent. The solar cell module of the second embodiment of the present invention has the sectional structure of FIG. 3, and the water trapping layer 8 is inserted only on the light incident side of the solar cell,
On the back surface side of the solar cell, an EVA film is used as an adhesive layer 62 and an aluminum foil is used as polyvinyl fluoride (PV).
A white film (Tedra-PVF, DuPont, trade name) 9 sandwiched with F) was used instead of the moisture-proof film 72.

The solar cell module of the third embodiment of the present invention has the cross-sectional structure of FIG. 1, and instead of the EVA film adhesive layers 61 and 62 and the water catching layer 8 of the first embodiment, Nylon-6 film coated with a polyolefin adhesive layer on one side (Toray Gosei Co., Ltd., product number: # 100)
0) was used. The solar cell module according to the fourth embodiment of the present invention has the cross-sectional structure shown in FIG.
Trifluorinated ethylene chloride with one surface roughened (PCTF
E) (Daikin Co., Ltd., trade name: Daiflon) The same as in the case of the first embodiment except that a moisture-proof film was used.

The thin-film solar cell of the fifth embodiment of the present invention has the cross-sectional structure of FIG. 1, and instead of the EVA film adhesive layers 61 and 62 and the polyphenylene sulfide moisture-proof films 71 and 72 of the first embodiment. A PCTFE (manufactured by Nitto Denko Corporation, product number: # 4820) moisture-proof film having a polyolefin adhesive layer adhered to one surface in advance was used. The following two types of solar cell modules were manufactured for comparison tests.

First Comparative Example: The same as the first example except that the water catching layer 8 of the solar cell module of the first embodiment and the adhesive layers 61 and 62 inside thereof were removed. Second Comparative Example The same as in the case of the first example except that the water trapping layer 8 of the solar cell module of the first example uses a non-roughened nylon-6 film.

The solar cell modules of these five types of examples and two types of conventional examples have a structure in which lead wires can be drawn from the electrodes to the outside to evaluate the characteristics. Characteristic evaluation is
A high temperature and high humidity test was performed for 2000 hours at 60 ° C. and 95% RH. As a result, no change in appearance was observed in all of the first to fifth examples, and in the first and second comparative examples, the module end portions were slightly discolored to black. In the second comparative example, a nylon film not roughened on one side was used for the water catching layer 8, but the adhesive layer 6 on the solar cell side was used.
It is considered that the above results were obtained because the adhesion with Nos. 1 and 62 deteriorated.

Further, as a result of measuring the conversion efficiency in the solar cell output characteristics, the same value as the initial value was shown in each example, but it was reduced by 1 to 1.5% in the comparative example.

[0015]

According to the present invention, in a thin film solar cell in which at least a first electrode layer, a photoelectric conversion semiconductor layer, and a transparent second electrode layer are laminated on a flexible substrate and sandwiched by two moisture-proof films. Since the water trapping layer is provided on the inner surface side of at least one of the moisture barrier films, the moisture trap layer exhibits hygroscopicity and water retention to improve the moisture barrier property, and has a long life and excellent long-life solar resistance. You can get a battery.

In particular, when a water catching layer is formed by using a polyamide resin film or the like having both surfaces in contact with the adhesive layer, and when at least one surface contacting the adhesive layer is roughened, the water catching layer is formed. When it is formed, the adhesiveness of the water trapping layer is improved, and the above effect becomes more remarkable.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a solar cell module according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a structure of a conventional solar cell module.

FIG. 3 is a sectional view showing the structure of a solar cell module according to another embodiment of the present invention.

[Explanation of symbols]

 1 Insulating film substrate 2 First electrode layer 3 Amorphous semiconductor layer 4 Transparent second electrode layer 5 Third electrode layer 61 Transparent adhesive layer 62 Adhesive layer 71 Transparent moisture-proof film 72 Moisture-proof film 8 Water replenishment layer 9 White film

Claims (4)

[Claims] 1. At least a first electrode layer on a flexible substrate,
A thin film solar cell comprising a photoelectric conversion semiconductor layer and a transparent second electrode layer laminated and sandwiched by two moisture-proof films, wherein at least one moisture-proof film has a water catching layer on the inner surface side. . 2. The water trapping layer is made of a polyamide resin.
The thin film solar cell described. 3. The water trapping layer is in contact with both sides of the adhesive layer.
Alternatively, the thin-film solar cell described in 2. 4. The thin-film solar cell according to claim 3, wherein the inner surface of the water-capturing layer, which is in contact with the adhesive layer, is roughened.