JP2003188394A - Solar cell film and solar cell module - Google Patents

Abstract

(57) [Summary] [Problem] To provide a solar cell module with high conversion efficiency at low cost by imparting a function of confining incident light to a substrate or a cover film laminated outside a cell part of a solar cell. Was desired. The present invention provides a solar cell film for cell portion lamination, which has a light confined shape having an uneven structure in which a film or a layer constituting the film is arranged. Thus, the unevenness directly arranged on the protective film is processed to effectively confine sunlight in the solar cell element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective film for a solar cell and a solar cell module using the film, and more specifically, a film used outside the cell of the solar cell, which protects light incident on the solar cell. The present invention relates to a solar cell film having a function of confining incident light so that it can be effectively used for power generation, and a solar cell module having improved conversion efficiency using the film.

[0002]

2. Description of the Related Art In conventional solar cells, SnO having a texture structure is used in order to effectively utilize incident light.
₂ A structure using a transparent conductive film is well known. In particular, the use of a SnO ₂ transparent conductive film having a textured structure
This is effective in improving the utilization efficiency of incident light and improving the output power. Generally, the textured SnO ₂ electrode has a thermal CV.
It is formed by growing crystal grains having a diameter of several tens to several hundreds nm on the electrode surface by the D method.

Further, in Japanese Patent Laid-Open No. 2000-323734, an attempt has been made to improve the utilization efficiency of sunlight by laminating a layer having a light trapping effect on a protective film for a solar cell.

[0004]

However, the above-mentioned S
Since the reaction temperature of the nO ₂ electrode is extremely higher than that of a general ITO electrode film, the process itself is costly, and a solar cell having a base material such as an organic polymer film that cannot withstand the high temperature is used. It has the drawback that it cannot be applied to modules.

Further, even when a layer having an optical confinement effect is laminated on the protective film for a solar cell, it is necessary to separately form a confinement layer, which causes a problem that the cost becomes high.

The present invention has been made to solve the above problems, and an object thereof is to confine incident light in a substrate or a cover film laminated on the outside of the cell portion of a solar cell. It is to provide a solar cell module with high conversion efficiency at low cost by imparting a function.

[0007]

According to a first aspect of the present invention, there is provided an optical confinement shape having an uneven structure in which a film or a layer forming the film is arranged, for stacking a cell portion. The present invention provides a film for a solar cell. Thereby, the unevenness directly arranged on the protective film is processed so that sunlight can be effectively trapped in the solar cell element. Such a film for a solar cell can be effectively used as a cover film for a solar cell as well as a base material for a solar cell, and the base material film is appropriately selected in terms of material, thickness, etc. according to its application. However, it is possible to use those having necessary properties such as strength, heat resistance, weather resistance, and transparency.

By adopting such a constitution, the film for a solar cell of the present invention has an effect of confining light, so that the light incident on the solar cell can be repeatedly re-incident inside, and the conversion efficiency can be improved. It is possible to provide a solar cell module having improved efficiency.

Further, according to the present invention, since the substrate film is directly processed into irregularities, there is no need to separately form an optical confinement layer, so that there is an advantage that the solar cell module can be formed at low cost. Here, the cell portion refers to a light receiving portion actually required for photoelectric conversion in a solar cell or a solar cell element, and may include or not include a portion that contributes to photoelectric conversion even if light is received, such as a wiring layer. Of course, the cell portion is an independent cell, and it naturally includes the cell portion in the case where many cells are aggregated to form a solar cell.

The invention described in claim 2 is the film for a solar cell according to claim 1, which has an adhesive layer.

According to this structure, an adhesive layer for laminating in advance on the outside of the cell portion of the solar cell is laminated on the film which has been subjected to the optical confinement treatment in the constitution of the solar cell film of the invention described in claim 1. It is a composition. The film for a solar cell having such a structure can be particularly suitably used as a cover film for a solar cell.

According to a third aspect of the present invention, the uneven structure of the film is a continuously arranged uneven structure, and at least the height or depth of the uneven structure is 0.1 nm to 5 nm.
It is 00 micrometers, It is the film for solar cells of Claim 1 or 2 characterized by the above-mentioned.

In the above structure, the uneven structure may be any structure as long as it can confine light. For example, a convex stripe (ridge shape) having an inclined surface such as a triangular cross section, a trapezoid, a semicircle or the like, or A shape in which concave lines are arranged, a pyramid shape or the like, a pyramid-shaped pyramid shape, a trapezoid in which the upper part of the pyramid is cut, a hemispherical shape such as a dome shape, or a shape in which convex or concave portions such as a hemispherical shape with curvature is arranged is preferable, In particular, it is preferable that the angle (vertical angle) formed between the inclined surfaces facing each other in the arrangement of the convex portions or the concave portions of the pyramid shape such as a pyramid is 90.

The height or depth of the uneven structure is 0.1 n.
The range of m to 500 μm is preferable, and when the height or depth of the uneven structure is less than 0.1 mn or exceeds 500 μm, the effect of refracting and reflecting the light scattered to the outside to re-enter the inside is reduced. Therefore, it is not preferable.

The invention according to claim 4 is the film for a solar cell according to claim 3, wherein the outermost layer of the film for a solar cell has an antifouling layer. With such a configuration, the outermost surface of the solar cell module is less likely to be contaminated, and it is possible to prevent the generation efficiency from being deteriorated due to contamination or the like.

The invention of claim 5 is characterized in that the antifouling layer has photoactivity. Since the antifouling layer has photoactivity, dirt hardly adheres to the outermost surface of the module, and even if it adheres, it can be easily washed away by rain or the like.

[0017] According to a sixth aspect of the invention, antifouling layer according to claim 4, wherein the _{Rf- (OC 3 F 6) n} -O- (CF 2) m - (C
H ₂₎ and _{l -O- (CH 2) s -Si} ( characterized by comprising the OR ₃₎ perfluoropolyether group-containing silane coupling agent represented by _3. By forming the antifouling layer with such a material, it becomes difficult for dirt to adhere to the outermost surface of the module, and even if it adheres, it can be easily washed off.

The invention according to claim 7 is the film for solar cells according to any one of claims 3 to 6, wherein the film for solar cells has a hard coat layer. With such a structure, the strength of the solar cell element can be increased, and it becomes unnecessary to seal the module surface with glass or the like.

The invention according to claim 8 is the film for a solar cell according to any one of claims 3 to 7, which has a light coherent antireflection layer. With such a structure, the effect of confining sunlight can be further enhanced by using the light trapping structure and the antireflection film together.

The invention of claim 9 is the film for a solar cell according to any one of claims 3 to 8, which has a gas barrier layer. By stacking the gas barrier film, the solar cell element can be prevented from being deteriorated by water vapor or the like.

[0021] The invention according to claim 10 is based on claims 3 to 9.
The present invention relates to a solar cell module, wherein the solar cell film according to any one of the above items is provided on a solar cell. By using such a film for a solar cell, the conversion efficiency of the solar cell can be enhanced at low cost.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments such as a material and a manufacturing method used for manufacturing the film for a solar cell of the present invention will be described below. First, as the base film of the solar cell film of the present invention, polymethyl methacrylate, polycarbonate, polystyrene, polyethylene sulfide, polyether sulfone, polyolefin,
Uses polyethylene terephthalate, polyethylene naphthalate, triacetyl cellulose, polyvinyl fluoride film, ethylene-tetrafluoroethylene copolymer resin, weather resistant polyethylene terephthalate, weather resistant polypropylene, glass fiber reinforced acrylic resin film, glass fiber reinforced polycarbonate, polyimide, etc. can do. These may be used as a single film, but it is also possible to use a composite film in which two or more kinds are laminated.

In the solar cell module of the present invention, a solar cell element such as thin film silicon can be directly formed on the surface of the above solar cell film having an uneven structure, or the solar cell element can be formed on another substrate. It is also possible to form and to adhere the film for the present solar cell thereon.

When the adhesive layer is used, the thickness of the adhesive layer is not particularly limited, and the adhesive layer can be laminated on the substrate film or the like with a thickness suitable for the type and shape of the solar cell element. Regarding the lamination method, depending on the material of the adhesive layer and the thickness to be laminated,
For example, it can be laminated on the surface of the base film by an appropriate means such as a coating method using a solution or a dispersion, an extrusion coating method, a calendar coating method, a thermal laminating method, a dry laminating method.

The uneven structure is formed by pressure-bonding a base film to a mold material such as a mold and cooling it to form an uneven structure, mechanically providing an uneven structure by sandblasting, scribing with a laser, or chemically. There are a method of etching and a method of mechanically providing irregularities with plasma.
By directly providing the uneven structure on the base material in this way, light confinement can be realized at low cost.

As described above, the shape of the uneven structure is a corrugated shape in which convex or concave shapes having inclined surfaces such as triangular, trapezoidal, and semicircular cross sections are arranged, or pyramidal or pyramidal or pyramidal shapes. It is desirable to have a shape in which concaves or convexes such as a trapezoid that cut the upper part of the, a dome shape, or a hemispherical shape that has a curvature is arranged, especially with an array of quadrangular pyramidal convexes or concaves such as a pyramid, It is desirable that the angle (vertical angle) formed between the facing slopes is 90 ° or more, as shown in FIG. The height or depth of the uneven structure is preferably 0.1 nm to 500 μm.

The antireflection film utilizes the coherence of light and is generally composed of a layer having a predetermined optical film thickness nd (refractive index n 3 film thickness d) in order to obtain a desired antireflection property. Of course, the number of layers is not particularly limited in the present invention. As the antireflection film, a low-refractive index layer such as a silicon oxide or an organic fluorine compound may be provided as a single layer, but it is usually preferable to have 1 to 6 layers in terms of cost and antireflection effect. The antireflection film is a vacuum deposition process such as a vacuum deposition method, a reactive deposition method, an ion beam assisted deposition method, a sputtering method, an ion plating method, a plasma CVD method, a wet coating such as a gravure coat or a screen coat, and heat drying. Method, a thermosetting method, an ultraviolet irradiation curing method, an electron beam irradiation curing method, etc. can be used, and an optimal method can be selected as appropriate for the characteristics of each thin film. Any other film forming method may be used.

A photoactive substance having a photocatalytic action is prepared according to the present invention.
It can be used on the outermost surface of the joule. Such a configuration
By removing dust on the surface of the antifouling layer by the action of light.
It decomposes and becomes low molecular weight to destroy the adhesiveness and wash with rain and fog
It also helps to keep the surface clean by flushing
It is a substance. For example, TiO₂, ZnO, SrTi
O₃, CdS, CaP, InP, GaAs, BaTi
O₃, K₂TiO₃, K₂NbO₃, Fe₂O₃, Ta₂O₃,
WO₃, SnO ₂, Bi₂O₃, NiO, Cu₂O, Si
C, SiO₂, MoS₂, InPb, RuO ₂, CeO₂Na
Doya, Pt, Rh, RuO₂, Nb, Cu, S
Metals such as n, Ni, Fe and / or oxidation of these metals
It is possible to use a composition in which a substance is mixed.

The antifouling layer made of a photoactive substance having a photocatalytic action can be provided by vapor deposition or sputtering.
It can also be applied.

Further, a material comprising a perfluoropolyether group-containing silane coupling agent can be used instead of the substance having a photocatalytic action. Especially Rf- (OC _{3
F 6) n -O- (CF 2} ) m - (CH 2) l -O- (CH 2) s
Excellent antifouling performance can be realized by using a perfluoropolyether group-containing silane coupling agent represented by —Si (OR ₃ ) ₃ .

[0031] _{Rf- (OC 3 F 6) n} -O- (CF 2) m -
(CH ₂₎ in _{l -O- (CH 2) s -Si} (OR 3) 3, Rf is a linear or branched perfluoroalkyl group having 1 to 16 carbon atoms, in particular CF ₃ -, C ₂ F _5- , C ₃ F
₇ -is preferred. Further, n is an integer of 1 to 50 and m is 0.
3 is an integer, 1 is an integer of 0 to 3, s is an integer of 0 to 6, R is an alkyl group having 1 to 10 carbon atoms, and 6 ≧ m + l>
0 is preferable, and —CH ₃ and —C ₂ H ₅ are particularly preferable. These antifouling layers are formed by wet coating (dip coating, flow coating, spray coating, roll coating, gravure coating, etc.), PVD (Physical Vapor De).
position) method (vacuum vapor deposition method, reactive vapor deposition method, ion beam assist method, sputtering method, ion plating method, etc.), CVD (Chemical Vap)
or Deposition) method (plasma CVD method, photo CVD method, etc.) or the like.

When the gas barrier layer is provided, various gas barrier materials can be used. When the film for a solar cell of the present invention is placed on the light incident side of the solar cell, the barrier layer is required to have not only excellent barrier properties against water vapor and oxygen but also excellent transparency. . From that viewpoint, any one of silicon oxide (SiOx), silicon nitride (SiNx), and aluminum oxide (AlxOy), or a vapor-deposited layer of two or more kinds, or an inorganic-organic hybrid coat layer Any one of the above or a composite layer in which two or more thereof are combined can be preferably used.

The above silicon oxide (SiOx), silicon nitride (SiNx), aluminum oxide (AlxOy)
The vapor deposition layer such as can be easily formed on the substrate film by a vapor deposition method, a sputtering method, a CVD method, a dipping method, a sol-gel method, or the like. A suitable thickness of such a barrier layer is in the range of 5 to 500 nm, and particularly 30 to 150 nm.
The range of nm is preferred.

The solar cell or solar cell element of the present invention means one that generates electricity by utilizing the photovoltaic effect of a semiconductor, and is a silicon (single crystal system, polycrystal system, amorphous system) solar cell, Compound semiconductor (3-5 group, 2-6
Group, other) solar cells, wet solar cells, dye-sensitized solar cells, organic semiconductor solar cells, and the like.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings. However, the present invention is not limited to these drawings. The invention described in claim 1 is a film that can be used by being laminated on the outside of a cell portion of a solar cell or a film that can be used as a base material of a thin-film solar cell, and has an uneven shape that plays a role of optical confinement. It has a film or a laminated film in which a plurality of layers are laminated on the film. For example, the configuration shown in FIGS. 1 to 7 can be adopted.

The solar cell film shown in FIG. 1 is an example in which a light confining structure having an uneven structure is processed on the light incident side of the film, and a solar cell element is laminated on the other surface of the film.

The solar cell film shown in FIG. 2 is processed with a light confinement structure having an uneven structure on the side opposite to the light incident side of the film, and the solar cell element is laminated directly on the uneven structure. Here is an example. The solar cell film shown in FIG. 3 is an example in which an optical confinement structure having an uneven structure is processed on both surfaces of the film, and a solar cell element is formed on either one of them. FIG. 4 is an example in which the solar cell element is laminated on the light confinement side of the uneven structure. In this example, light is incident from the solar cell element side, not the solar cell film side, The film may or may not transmit light.

Although not shown in the figure, in the above structure, an antireflection layer, a gas barrier layer and a hard coat layer as described above may be provided on any layer of the solar cell film, if necessary. It is possible to provide a protective layer such as a film laminate or a resin coating on the protective layer. It is also preferable to provide an antifouling layer on the outermost surface of the solar cell film.

By adopting such a constitution, as described above, it is excellent in strength, heat resistance, weather resistance, transparency, gas barrier property, and the like, and the light incident on the solar cell is repeatedly regenerated inside. It can be made incident and the conversion efficiency can be improved.

In the examples shown in FIGS. 1 to 4, since a solar cell is directly produced on the film of the present invention, a thin film silicon solar cell (amorphous silicon, microcrystalline silicon, polycrystalline silicon, etc.), amorphous silicon, compound semiconductor Type and organic compound type thin film solar cells and dye-sensitized solar cells are desirable.

The invention described in claim 2 is one in which a film for a solar cell having a light trapping effect is laminated on a solar cell element with an adhesive layer interposed therebetween, an example of which is shown in FIG.

That is, FIGS. 5 to 7 are cross-sectional views showing respective embodiments, and the one shown in FIG. 5 is the outside of the base film, that is, the light incident side is subjected to the light confinement process, and the inside, that is, the sun. It has a constitution in which an adhesive layer for laminating on the cell portion of the solar cell is provided on the side laminated on the battery, and the one shown in FIG. 6 has an adhesive layer provided on the inside of the base film, that is, on the side laminated on the solar cell. It has a different structure. Further, FIG. 7 shows a structure in which both sides of the base film are subjected to light confinement processing.

Although not shown in the figure, in the above-mentioned constitution, if necessary, an antireflection layer, a gas barrier layer and a hard coat layer as described above may be provided on any layer of the solar cell film. In addition, a protective layer such as a film laminate or a resin coating can be further provided on it. It is also preferable to provide an antifouling layer on the outermost surface of the solar cell film.

By adopting such a constitution, as described above, the strength, heat resistance, weather resistance, transparency, gas barrier properties, etc. are excellent, and the light incident on the solar cell is repeatedly regenerated inside. It can be made incident and the conversion efficiency can be improved.

In the examples shown in FIGS. 5 to 7, thin film silicon solar cells (amorphous silicon, microcrystalline silicon, polycrystal silicon, etc.), amorphous for laminating the film of the present invention on a solar cell element via an adhesive layer are used. silicon,
It is applicable not only to compound semiconductor-based or organic compound-based thin-film solar cells and dye-sensitized solar cells, but also to bulk solar cells such as single crystal Si solar cells.

The present invention will be more specifically described below with reference to Examples and Comparative Examples.

[Example 1] One of weather-resistant PET (polyethylene terephthalate; the same applies hereinafter) (thickness 188 μm) was formed in a corrugated shape in which triangular prisms as shown in FIG. 9 were laid sideways and the height was 6 μm. A mold having an uneven structure with an apex angle of 90 ° was pressure-bonded for 2 minutes while applying heat at 80 ° C., and the above uneven structure was formed on one surface of the weather-resistant PET.

Example 2 Weatherproof PET (thickness 188 μ
m) with a corrugated shape in which triangular prisms are laid sideways on both surfaces and having a convex / concave structure with a height of 6 μm and an apex angle of 90 ° while heating at 80 ° C. for 2 minutes. Crimp,
The above-mentioned uneven structure was provided on both surfaces of the weather resistant PET.

[Comparative Example] PET having no uneven structure was prepared.

[Tests and Results] In order to evaluate the films for solar cells of Examples 1 and 2 and Comparative Example 1 produced as described above, a tin oxide (ITO) thin film in which indium was added to one surface of the above film. Was formed by sputtering with a thickness of 450 nm. Further, an amorphous silicon thin film is formed on the p-layer (25 nm) and i-layer (350 n) by the plasma CVD method.
m) and n layers (20 nm) were laminated in this order and a 300 nm Ag vapor deposition layer was formed as a reflective layer to prepare a solar cell module, and the short circuit current of each was measured to confirm the light confinement effect. The results are summarized in Table 1.

[0051]

[Table 1]

As is clear from the results shown in Table 1, in the solar cell modules using the solar cell films of Examples 1 and 2, the short-circuit current was larger than that of the solar cell module of Comparative Example 1, and the optical confinement was performed. The effect of improving the short-circuit current due to the effect was recognized.

[0053]

As described above in detail, according to the present invention, a film for a solar cell, which is excellent in light resistance, strength and gas barrier property, and which can improve the short-circuit current and thus the conversion efficiency, can be manufactured at low cost. Can be supplied.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view illustrating the configuration of an embodiment of the solar cell module of the present invention.

FIG. 2 is a schematic cross-sectional view illustrating the configuration of an embodiment of the solar cell module of the present invention different from that of FIG.

FIG. 3 is a schematic cross-sectional view explaining the configuration of an embodiment of the solar cell module of the present invention different from FIGS.

FIG. 4 is a schematic cross-sectional view illustrating the configuration of an embodiment of the solar cell module of the present invention, which is different from FIGS.

FIG. 5 is a schematic cross-sectional view illustrating the configuration of an embodiment of the solar cell module of the present invention, which is different from FIGS. 1 to 4.

FIG. 6 is a schematic cross-sectional view illustrating the configuration of an embodiment of the solar cell module of the present invention, which is different from FIGS. 1 to 5.

FIG. 7 is a schematic cross-sectional view illustrating the configuration of an embodiment of the solar cell module of the present invention, which is different from FIGS. 1 to 6.

FIG. 8 is a schematic cross-sectional view illustrating the configuration of an example of the solar cell film of the present invention.

9 is a schematic cross-sectional view illustrating the configuration of an example of a solar cell film of the present invention, which is different from FIG.

[Explanation of symbols]

Film for solar cells 2 solar cells 3 uneven structure 4 Adhesive layer

Claims (10)

[Claims] 1. A film for a solar cell for laminating a cell part, which has an optical confinement shape having an uneven structure in which a film or a layer constituting the film is arranged. 2. The solar cell film according to claim 1, which has an adhesive layer. 3. The uneven structure of the film is a continuously arranged uneven structure, and the height or depth of at least the uneven structure is 0.1 nm to 500 μm. 2. The film for a solar cell according to 2. 4. The solar cell film according to claim 3, wherein an antifouling layer is provided as an outermost layer of the solar cell film. 5. The solar cell film according to claim 4, wherein the antifouling layer of the solar cell film has photoactivity. 6. The antifouling layer of the solar cell film is Rf-
_{(OC 3 F 6) n -O-} (CF 2) m - (CH 2) l -O-
_{(CH 2) s -Si (OR} 3) for a solar cell according to claim 4, characterized in that it consists of Pearl full Oro polyether group-containing silane coupling agent represented by the ₃ films. 7. The solar cell film according to claim 3, wherein the solar cell film has a hard coat layer. 8. The solar cell film according to claim 3, further comprising a light coherent antireflection layer. 9. The film for a solar cell according to claim 3, which has a gas barrier layer. 10. A solar cell module comprising the solar cell film according to any one of claims 3 to 9 provided on a solar cell.