Solar cell and manufacturing method thereof

Abstract

To provide a solar cell and a manufacturing method thereof that can ensure gas barrier properties while reducing the amount of polysilazane used.SOLUTION: A solar cell 10 includes a laminate 11 in which a photovoltaic layer 12 is sandwiched between protective layers 13, and a ceramic coating 15 containing a polysilazane component is fixed to the end face 11a of the laminate 11 all around.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a solar cell having a laminate in which a photovoltaic layer is sandwiched between protective layers, and a method for manufacturing the same. [Background technology]

[0002] In conventional solar cells of this type, in order to improve the gas barrier properties against oxygen and water vapor, a technique has been proposed in which the photovoltaic layer is covered with a polysilazane coating, which has high gas barrier properties, in addition to or instead of protective layers (e.g., synthetic resin barrier films) placed on the front and back sides. In the solar cell disclosed in Patent Document 1, the entire photovoltaic layer is protected by being placed in a sealing layer made of polysilazane. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6876480 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a method such as that described in Patent Document 1, in which polysilazane is arranged so as to surround the photovoltaic layer from all directions, a large amount of expensive polysilazane is required to form one solar cell, which may result in high costs.

[0005] The present invention has been proposed in consideration of the above circumstances, and its object is to provide a solar cell that can ensure gas barrier properties while reducing the amount of polysilazane used, and a method for manufacturing the same. [Means for solving the problem]

[0006] In order to achieve the above object, the solar cell of the present invention is a solar cell having a laminate in which a photovoltaic layer is sandwiched between protective layers, and is characterized in that a ceramic coating containing a polysilazane component is fixed to the end faces of the entire periphery of the laminate.

[0007] The method for manufacturing a solar cell of the present invention is characterized in that a hydrophilic region and a water-repellent region adjacent to the hydrophilic region are formed on a working surface, the laminate is placed on the working surface so that its outer edge is contained within the hydrophilic region in a planar view, and a liquid ceramic coating agent is dripped onto the end surface to form the ceramic coating.

[0008] Another method for manufacturing a solar cell of the present invention is characterized in that a water-repellent region and an ultra-water-repellent region adjacent to the water-repellent region are formed on a work surface, a liquid ceramic coating agent is dripped onto the water-repellent region to form liquid protrusions, and the laminate is positioned so that its end face is in contact with the liquid protrusions, thereby forming the ceramic coating. [Effects of the Invention]

[0009] Since the solar cell of the present invention has the above-described configuration, it is possible to ensure gas barrier properties while reducing the amount of polysilazane used.

[0010] Since the method for producing a solar cell of the present invention employs the above-described procedure, it is possible to produce a solar cell that ensures gas barrier properties while reducing the amount of polysilazane used. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic vertical cross-sectional view of a solar cell according to one embodiment of the present invention. [Figure 2] 2A to 2C are schematic vertical cross-sectional views illustrating a method for manufacturing the solar cell of FIG. [Figure 3] 1. FIG. 4 is a schematic vertical cross-sectional view showing another method for manufacturing the solar cell of FIG. [Figure 4] FIG. 1 is a schematic vertical cross-sectional view showing an example of a flexible solar cell. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, the basic configuration of the solar cell 10 according to the embodiment will be described.

[0013] The solar cell 10 has a laminate 11 formed by sandwiching a photovoltaic layer 12 between protective layers 13. A ceramic coating 15 containing a polysilazane component is adhered to and formed on the end face 11a of the entire periphery of the laminate 11.

[0014] The polysilazane component includes silica glass that is formed by the transformation (conversion) of polysilazane through a chemical reaction with water.

[0015] Next, the solar cell 10 according to this embodiment will be described in detail. The solar cell 10 exemplified below is a perovskite solar cell, and is assumed to have a thickness of approximately 0.1 mm to 1.0 mm. This solar cell 10 is used as a flexible solar cell 30, as will be described later with reference to FIG. 4. The present invention is applicable not only to perovskite solar cells, but also to amorphous silicon solar cells, dye-sensitized solar cells, and organic thin-film solar cells.

[0016] A perovskite solar cell is a solar cell 10 that has a perovskite layer made of an organic material with a unique crystal structure known as a perovskite structure as a power generation layer (not shown). The perovskite layer itself is extremely thin, about 1 μm thick.

[0017] As shown in the longitudinal cross section of Figure 1, the laminate 11 of the solar cell 10 has protective layers 13 arranged in close contact with the top and bottom surfaces of the photovoltaic layer 12, and the protective layers 13 are fixed together with an adhesive.

[0018] Although plan views of the solar cell 10 and the laminate 11 are omitted, the planar shape and dimensions of the upper and lower protective layers 13 are identical, with no misalignment in plan. The planar shape of the laminate 11 is a substantially rectangular shape that matches the planar shape of the protective layer 13. The photovoltaic layer 12 has smaller planar dimensions than the protective layer 13 and is disposed in the center of the protective layer 13 in plan view. At least one surface of this photovoltaic layer 12 serves as a light-receiving surface for receiving light.

[0019] An adhesive layer 14 is filled between the protective layers 13 on the sides of the photovoltaic layer 12 up to the periphery of the protective layer 13. This adhesive layer 14 is a layer formed by hardening an adhesive used to bond the protective layers 13 together, and is disposed without gaps in the space on the sides of the photovoltaic layer 12 disposed between the protective layers 13.

[0020] The protective layer 13 may be formed by coating a synthetic resin film base with an inorganic material by vapor deposition or the like. Specifically, a polypropylene film or the like may be coated with silica, alumina, aluminum, silicon nitride, or the like.

[0021] Assuming that the laminate 11 has a thickness of, for example, about 0.1 mm to 1.0 mm, it is desirable to use a thin synthetic resin film for the protective layer 13. Since it is required to reduce the thickness and also to increase the light conversion efficiency, the protective layer 13 must be able to sufficiently block oxygen and water vapor. In order to improve the gas barrier properties against oxygen and water vapor, it is desirable to use a synthetic resin film coated with an inorganic material that has high gas barrier properties as the protective layer 13. Methods for coating a synthetic resin film with an inorganic material include vapor deposition (PVD), sputtering, and chemical vapor deposition (CVD).

[0022] Furthermore, taking into consideration the gas barrier properties against oxygen and water vapor, specific types of synthetic resin material that are the base material of protective layer 13 include low-density polyethylene (LDPE), high-density polyethylene (HDPE), solid polypropylene (CPP), oriented polypropylene (OPP), polyethylene terephthalate (PET), and cycloolefin polymer (COP).

[0023] The gas barrier properties can be measured by oxygen permeability (unit: ml / m²·day·MPa) and water vapor permeability (unit: g / m²·day), and the smaller these values ​​are, the higher the gas barrier properties can be determined. The water vapor permeability of the protective layer 13 is 5×10 -3 The oxygen permeability of the protective layer 13 is preferably 1×10 -4 It is desirable to keep it below ml / m2·day·MPa.

[0024] PET has an oxygen permeability of approximately 600 ml / m²·day·MPa and a water vapor permeability of approximately 27 g / m²·day, which are smaller than other materials and can be said to have a high gas barrier property as an organic material. PET is also inexpensive, making it a particularly suitable material among the synthetic resin materials mentioned above.

[0025] LDPE, HDPE, CPP, and OPP have water vapor permeabilities similar to those of PET, but oxygen permeabilities of 5000 ml / m2·day·MPa or higher. Other synthetic resin materials, such as unstretched nylon, stretched nylon, stretched polystyrene, and polycarbonate, may also be used.

[0026] The protective layer 13 may be any such synthetic resin film coated with an inorganic material to enhance its gas barrier properties. For example, a single-layer PET film with alumina vapor deposition has an oxygen permeability of approximately 0.1 ml / m²·day·MPa and a water vapor permeability of approximately 0.05 g / m²·day. By stacking multiple single-layer PET films with alumina vapor deposition, the water vapor permeability of the protective layer 13 can be increased to 5×10 -3It is particularly important to reduce the water vapor permeability of the photovoltaic layer 12 because the photovoltaic layer 12 ionizes in the presence of water vapor.

[0027] Furthermore, it is desirable that the protective layer 13 be made of an inorganic material such as a glass plate or a laminate of a glass plate and a synthetic resin film. In other words, three types of materials are conceivable for the protective layer 13: a synthetic resin film, a glass plate, and a laminate of these. Furthermore, different types of protective layers 13 may be disposed above and below.

[0028] Glass has a water vapor permeability and oxygen permeability of almost zero and has high gas barrier properties, making it suitable for use as protective layer 13. However, thin glass is more fragile than synthetic resin films, so it is desirable to use a synthetic resin film or a laminate of synthetic resin film and glass as the base material for protective layer 13 of a flexible solar cell.

[0029] In order to properly and efficiently receive light, it is desirable to use a highly transparent material for at least the protective layer 13 disposed on the light-receiving side of the solar cell 10. Of course, both protective layers 13 may be made of a highly transparent material.

[0030] It is desirable to use an adhesive that has excellent transparency, adhesion, thermal expansion absorption, and shock absorption properties, such as transparent acrylic, silicone, polyolefin, polyurethane, or ethylene vinyl acetate, as the adhesive for forming adhesive layer 14. The water vapor permeability of polyurethane adhesives is approximately 37 g / m²·day.

[0031] 1, the solar cell 10 further includes a ceramic coating 15, primarily made of an inorganic material, formed on the end surface 11a of the laminate 11. The ceramic coating 15 contains silica glass formed by the reaction of a polysilazane liquid with moisture in the air.

[0032] The ceramic coating 15 may be composed solely of silica glass obtained by converting polysilazane liquid, or may contain materials other than the polysilazane component, such as indium oxide, silica, alumina, etc. Silica glass obtained by converting polysilazane liquid has extremely high gas barrier properties, with water vapor permeability and oxygen permeability being almost zero.

[0033] In this way, since the end face 11a of the laminate 11 is covered with the ceramic coating 15 containing a polysilazane component, the photovoltaic layer 12 in the laminate 11 is also suitably protected from the end face 11a side.

[0034] In this way, the gas barrier properties are improved by covering the top and bottom of the photovoltaic layer 12 with protective layers 13 containing an inorganic material, while the gas barrier properties are improved by covering the side surfaces of the photovoltaic layer 12 (end surfaces 11a of the laminate 11) with ceramic coatings 15 containing a polysilazane component.

[0035] In particular, since a layered surface (cross section of multiple layers) including an organic adhesive layer 14 appears on the end surface 11a of the laminate 11, it is effective to use a ceramic coating 15 with strong gas barrier properties as the coating for the end surface 11a.

[0036] Although organic adhesive layer 14 is disposed on the side adjacent to photovoltaic layer 12, as described above, organic adhesive layer 14 does not have good gas barrier properties by itself, and therefore adhesive layer 14 alone is naturally insufficient to improve the gas barrier properties for photovoltaic layer 12. In other words, it is extremely difficult to ensure high gas barrier properties for photovoltaic layer 12 by constructing solar cell 10 using only laminate 11 without covering end face 11a with ceramic coating 15.

[0037] Furthermore, instead of an organic adhesive, a ceramic coating agent containing a polysilazane liquid may be used as the adhesive between the protective layers 13. That is, the adhesive layer 14 between the protective layers 13 and the ceramic coating 15 covering the end surface 11a of the laminate 11 may be integrally formed from a cured material containing a polysilazane component. Furthermore, the adhesive layer 14 and the ceramic coating 15 may be formed from different inorganic materials.

[0038] In this type of solar cell 10, the adhesive layer 14 and the ceramic coating 15 of the laminate 11 are both made of inorganic materials, so that the gas barrier properties on the side surfaces of the photovoltaic layer 12 can be strengthened.

[0039] Next, a method for manufacturing the solar cell 10 will be described with reference to Figures 2 and 3. As described above, the solar cell 10 according to this embodiment is in the form of a thin film, and the surface area of ​​the end face 11a is extremely small, so it is difficult to use a vapor deposition method to form the ceramic coating 15 on the end face 11a. Of course, it is also difficult to apply a material directly to the end face 11a.

[0040] Therefore, the following procedure for forming a coating on the end surface 11a is preferably used. The method for manufacturing this solar cell 10 is a method having the following procedure for forming a coating. Note that a description of the procedure for forming the laminate 11 will be omitted. The following description will be given along steps A1 to A4 shown in FIG. 2.

[0041] First, the planar working surface 20 is surface-modified to form a hydrophilic region 21 and a water-repellent region 22 adjacent to the hydrophilic region 21. Specifically, a strip-shaped hydrophilic region 21 is formed along the outer edge of a rectangle that roughly matches the planar shape of the laminate 11, and water-repellent regions 22 are formed on both the inside and outside of the strip-shaped hydrophilic region 21.

[0042] In other words, the water-repellent region 22 is formed in the center of the work surface 20 to match the planar dimensions of the laminate 11, and then a square-ring-shaped hydrophilic region 21 is formed around the water-repellent region 22, and the width of the hydrophilic region 21 is appropriately determined to match the height of the end face 11a of the laminate 11 (see step A1 in FIG. 2 for the above).

[0043] Next, the laminate 11 is placed in the water-repellent region 22 surrounded by the hydrophilic region 21 so that the outer periphery of the laminate 11 fits within the hydrophilic region 21 in plan view (see step A2 in FIG. 2).

[0044] Then, a liquid ceramic coating agent 26 containing a polysilazane liquid is dropped onto the end face 11a. The dropped ceramic coating agent 26 covers the entire end face 11a (layered surface) by adsorption, and excess liquid is diffused over the surface of the hydrophilic region 21 on the working surface 20 (see step A3 in FIG. 2).

[0045] At this time, no droplets form on the hydrophilic region 21, which remains wet, and the ceramic coating agent 26 remains covering the end surface 11a of the laminate 11. Furthermore, if there is excess liquid that cannot be absorbed by the hydrophilic region 21, the excess liquid moves to the water-repellent region 22, but the liquid is repelled by the water-repellent region 22, forming droplets.

[0046] When the ceramic coating agent 26 has completely covered the end face 11a, or when droplets begin to form in the water-repellent region 22, the dripping of the ceramic coating agent 26 is stopped, and the ceramic coating agent 26 on the end face 11a is heated in this state. By heating the ceramic coating agent 26 on the end face 11a, the ceramic coating agent 26 hardens. Specifically, while the ceramic coating agent 26 is being heated, the polysilazane liquid contained in the ceramic coating agent 26 reacts with moisture in the air and is converted into silica glass, resulting in a ceramic coating 15 containing silica glass (see step A4 in FIG. 2).

[0047] In this way, the ceramic coating 15 can be formed on the end surface 11a of the laminate 11 by simple work on the work surface 20. Because this method effectively utilizes the functions of the hydrophilic region 21 and the water-repellent region 22, the ceramic coating agent 26 is not wasted, and expensive materials can be saved.

[0048] 3 also makes it possible to easily form ceramic coating 15 and reduce the amount of material used for ceramic coating agent 26. Steps B1 to B4 shown in FIG. 3 will be described below.

[0049] First, a water-repellent region 23 and an ultra-water-repellent region 24 (or highly water-repellent region; hereinafter the same) adjacent to the water-repellent region 23 are formed on the working surface 20. Specifically, the ultra-water-repellent region 24 is formed in the center of the working surface 20 to match the planar dimensions of the laminate 11, and then a square-ring-shaped water-repellent region 23 is formed around the ultra-water-repellent region 24, and another ultra-water-repellent region 24 is formed around the ring-shaped water-repellent region 23. The width of the water-repellent region 23 can be determined appropriately to match the height of the end face of the laminate 11 (see step B1 in Figure 3 for the above).

[0050] Next, a liquid ceramic coating agent 26 containing a polysilazane liquid is dropped onto the water-repellent region 23 to form liquid protrusions 28. Since the liquid agent is dropped onto the water-repellent region 23, droplets are formed due to the water-repellent effect, and these droplets form continuous protrusions along the water-repellent region 23.

[0051] At this time, since the area adjacent to the water-repellent area 23 is the ultra-water-repellent area 24, the ceramic coating agent 26 does not easily move to the adjacent area, and a liquid protrusion 28 is formed around the water-repellent area 23 (see step B2 in FIG. 3 for the above).

[0052] Then, the laminate 11 is placed in the ultra-water-repellent region 24 surrounded by the water-repellent region 23 so that the end face 11a contacts the liquid protrusion 28, and the ceramic coating agent 26 that constitutes the liquid protrusion 28 is adsorbed onto the end face 11a so as to cover it (see step B3 in Figure 3).

[0053] After confirming that the ceramic coating agent 26 has covered substantially the entire end face 11a, the ceramic coating agent 26 that has covered the end face 11a is heated. Heating the ceramic coating agent 26 causes the ceramic coating agent 26 to harden. Specifically, while the ceramic coating agent 26 is being heated, the polysilazane liquid contained in the ceramic coating agent 26 reacts with moisture in the air and is converted into silica glass, thereby obtaining a ceramic coating 15 containing silica glass (see step B4 in FIG. 3).

[0054] 2 and 3, the ceramic coating agent 26 is heated and cured, but the polysilazane liquid can be converted to silica glass if it contains moisture, so a method without heating may be used. Also, a curing agent may be added to the ceramic coating agent 26 to cause it to harden.

[0055] Furthermore, as a method for manufacturing solar cell 10 in which adhesive layer 14 between protective layers 13 and ceramic coating 15 covering end face 11a of laminate 11 are integrally formed from a cured product containing a polysilazane component, the following method, for example, can be adopted instead of directly using the method shown in Figures 2 and 3.

[0056] That is, this type of solar cell 10 can be manufactured by sequentially placing a protective layer 13 (protective film), a photovoltaic layer 12 (photovoltaic film), and a protective layer 13 (protective film) on a porous water-repellent sheet, dropping a ceramic coating agent 26 containing a polysilazane liquid onto the end surfaces, and, before hardening, applying pressure from above while drawing a vacuum from below the porous water-repellent sheet.

[0057] In other words, in this method, the ceramic coating agent 26 containing the polysilazane liquid is used instead of an adhesive to form the adhesive 14. In this case, it is desirable to apply pressure as described above to prevent the polysilazane liquid from flowing between the photovoltaic layer 12 and the protective layer 13 and having adverse effects on the photovoltaic layer 12, such as a decrease in the photovoltaic effect. When an organic adhesive is used, the amount of organic solvent (concentration of the adhesive component) can be adjusted so that the organic solvent evaporates before the ceramic coating agent 26 is applied to the end face 11a of the laminate 11.

[0058] According to the method of using the ceramic coating agent 26 as the adhesive 14 in this manner, the adhesive layer 14 between the protective layers 13 and the ceramic coating 15 covering the end surface 11a of the laminate 11 are integrally formed from a cured product containing a polysilazane component, thereby further improving the gas barrier properties.

[0059] 2 or 3 may be used to form the ceramic coating 15 from the ceramic coating agent 26 on the laminate 11 on which the adhesive layer 14 is formed using the ceramic coating agent 26. In particular, when the adhesive layer 14 and the ceramic coating 15 are made of different inorganic materials, these manufacturing methods may be used.

[0060] Next, a flexible solar cell 30 formed by assembling a plurality of solar cells 10 shown in Fig. 1 to form, for example, a grid pattern in a plan view will be described with reference to the partial vertical cross-sectional view of Fig. 4. Note that a plan view is not shown.

[0061] The flexible solar cell 30 in Fig. 4 is formed by arranging multiple solar cells 10 in a grid pattern and sandwiching them from above and below with protective films 31. The solar cells 10 are separated into individual battery blocks 32, and connecting portions 34 are formed between adjacent battery blocks 32 by thermally welding the upper and lower protective films 31 together.

[0062] One laminate 11 is placed in a block space 33 surrounded by upper and lower protective films 31 in one battery block 32, and ceramic coatings 15 are fixed to the four peripheral end faces 11a of the laminate 11. In other words, one solar cell 10 is placed without any gaps in the block space 33.

[0063] The flexible solar cell 30 has connecting portions 34 formed vertically and horizontally to separate each battery block 32. The connecting portions 34 extend linearly in both the vertical and horizontal directions, intersecting each other, and the solar cell can be bent along the connecting portions 34.

[0064] The connecting portions 34 may be arranged only in either the vertical or horizontal direction. In this case, the block space 33 extends long in the vertical or horizontal direction, and multiple solar cells 10 are arranged side by side in the block space 33.

[0065] The flexible solar cell 30 described above can be used by being wrapped around a cylindrical object, for example, and furthermore, because it is a thin film, it can also be attached to curved or uneven surfaces without losing its curvature. For example, the flexible solar cell 30 can be attached to the outer surface of a bronze statue or other object to be installed outdoors, or to an indoor ornament.

[0066] The configurations and shapes of the solar cell 10 and flexible solar cell 30 according to the embodiments described above are merely examples, and it goes without saying that they can be appropriately changed to configurations and shapes other than those shown in the figures. [Explanation of symbols]

[0067] 10. Solar Cells 11 Laminate 11a End face 12 Photovoltaic layer 13 Protective layer 14 Adhesive layer 15 Ceramic coating 20 work surface 21 Hydrophilic region 22, 23 Water repellent area 24 Super water repellent area 26 Ceramic coating agent 28 Liquid protrusion 30 Flexible solar cells 31 Protective film 32 Battery Block 33 Block Space 34 Connecting part

Claims

1. A solar cell having a laminate in which a photovoltaic layer is sandwiched between protective layers, A solar cell characterized in that a ceramic coating containing a polysilazane component is fixed to the end faces of the entire periphery of the laminate.

2. In claim 1, a cured adhesive is disposed on the side of the photovoltaic layer between the protective layers; The end surface is a multi-layered surface including a central layer of the adhesive.

3. In claim 1, The solar cell is characterized in that the protective layer is formed by coating a synthetic resin film with an inorganic material.

4. In claim 1, The solar cell is characterized in that the protective layer is made of a glass plate or a laminate of a glass plate and a synthetic resin film.

5. A method for manufacturing a solar cell, comprising the steps of: manufacturing the solar cell according to claim 1; A hydrophilic area and a water-repellent area adjacent to the hydrophilic area are formed on the working surface; The laminate is placed on the work surface so that the outer edge of the laminate is within the hydrophilic region in a plan view; A method for manufacturing a solar cell, comprising: forming the ceramic coating by dropping a liquid ceramic coating agent containing a polysilazane liquid onto the end surface.

6. In claim 5, The laminate has a rectangular shape in a plan view, the hydrophilic region is a strip-shaped region along an outer edge of a rectangle that substantially matches the planar shape of the laminate, while the water-repellent region is a region adjacent to each of the inside and outside of the hydrophilic region; A method for manufacturing a solar cell, comprising placing the laminate on the water-repellent region located inside the hydrophilic region.

7. A method for manufacturing a solar cell, comprising the steps of: manufacturing the solar cell according to claim 1; A water-repellent area and an ultra-water-repellent area adjacent to the water-repellent area are formed on the work surface; a liquid ceramic coating agent containing a polysilazane liquid is dropped onto the water-repellent region to form liquid protrusions; A method for manufacturing a solar cell, characterized in that the ceramic coating is formed by placing the laminate so that the end faces are in contact with the liquid protrusions.

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