JP2010283051A - Laminate for solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve thinning of a silicon wafer for a solar cell. <P>SOLUTION: A laminate for the solar cell has a silicon wafer layer and a protective layer. The protective layer can have electrodes. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laminate for a solar cell.

  Single-crystal or polycrystalline solar cells are the most popular solar cells in terms of cost and conversion efficiency. However, from the viewpoint of further cost reduction and the like, thinning of the silicon wafer is required.

  However, if such a silicon wafer for solar cells is thinned to a thickness of 300 μm or less, the wafer is easily damaged during transportation or processing, and the wafer is likely to be warped during heat treatment.

  The inventor of the present invention has reached the present invention as a result of intensive studies on thinning the silicon wafer for solar cells.

That is, the present invention
1. A laminate for a solar cell having a silicon wafer layer and a protective layer;
2. The laminate as described in 1 above, having a protective layer on both sides or one side of the silicon wafer layer;
3. 3. The laminate as described in 1 or 2 above, wherein the thickness of the silicon wafer layer is 50 μm or more and 250 μm or less; and The laminated body as described in any one of the preceding items 1 to 3, wherein the protective layer has an electrode;
Is to provide.

  According to the present invention, it is easy to reduce the thickness of a silicon wafer for solar cells.

FIG. 1 is an example of a cross-sectional view of the laminate of the present invention. FIG. 2 is an example of a process for producing a crystalline Si solar cell.

  Hereinafter, the present invention will be described in detail. The present invention is a solar cell laminate having a silicon wafer layer and a protective layer.

  The thickness of the silicon wafer layer is usually 300 μm or less, preferably 50 μm or more and 250 μm or less.

  The protective layer may be provided on both sides of the silicon wafer layer, or may be provided only on one side. The base material of the protective layer is not particularly limited. For example, polyethylene, linear low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate, polyvinyl chloride, polyamide, polyethylene terephthalate, polyvinyl Synthetic resins such as alcohol, polyvinyl butyral, and silicone are used and may be a single body or a multilayer. The thickness is preferably in the range of 20 μm or more and 500 μm or less. A protective layer may be formed by laminating a film-like base material on a silicon wafer layer, or a liquid or gel-like fluid base material is applied to the surface of the silicon wafer and solidified for lamination. A protective layer may be formed by the above.

  The protective layer may have an electrode. Although there is no restriction | limiting in particular as an electrode material, For example, Ag, Al, Au, Cu etc. which are generally used as an electrode material for solar cells can be mentioned. Among them, as the back electrode material, Ag or Al is preferable from the viewpoint of electrical conductivity, and Al is more preferable in order to obtain a BSF (Back Surface Field) effect by forming a p + layer near the electrode in the silicon wafer. . The surface electrode is more preferably Ag from the viewpoint of electrical conductivity. The shape of the electrode in the protective layer is not particularly limited, but the surface electrode has a high aspect ratio (b / a value in FIG. 1 is 1 or more) from the viewpoint of efficiently absorbing sunlight. More preferred.

  An adhesive may be used when the film-like protective layer is laminated on the silicon wafer layer. There is no restriction | limiting in particular in an adhesive, For example, well-known adhesives, such as a solution type adhesive, an emulsion type adhesive, a hot-melt type adhesive, can be used. Specific examples include acrylic adhesives, vinyl ether adhesives, silicon adhesives, rubber adhesives, and the like. The thickness of the adhesive layer is preferably in the range of 1 μm to 200 μm.

  Next, the manufacturing method of the laminated body of this invention is demonstrated. The laminate of the present invention includes a first step of forming a protective layer on a planar surface of a silicon ingot, and a second step of cutting a silicon wafer layer parallel to the surface from a silicon ingot having a surface on which the protective layer is formed. It is manufactured by the method containing these. Moreover, this manufacturing method may further include a third step of forming a protective layer on a planar surface having no protective layer among the cut silicon wafer layers.

  The purity of the silicon ingot is not particularly limited as long as the silicon wafer layer to be cut out can be used for solar cells. The planar surface means a surface obtained by cutting a silicon wafer layer or an unnecessary portion from a silicon ingot. The protective layer may be formed by a method in which an adhesive is applied to the surface and a film-like substrate is applied thereon, or a film-like substrate to which an adhesive has been previously applied is applied to the surface. You may form by the method of sticking so that an adhesive may touch, and you may form by the method of apply | coating and solidifying fluid base materials, such as a liquid form and a gel form, to this surface.

  Examples of a method for cutting out a silicon wafer layer from a silicon ingot having a surface on which a protective layer is formed include a normal method such as a method using a band saw or a wire saw. What is necessary is just to cut | disconnect the location corresponded in the thickness of the silicon wafer layer for solar cells desired from the surface in which the protective layer obtained by a 1st process was formed.

  The formation of the protective layer in the third step may be performed in the same manner as in the first step.

  The laminated body for solar cells of this invention can remove a protective layer and an adhesion layer by heat processing and chemical treatment as needed, and can leave a silicon wafer layer. At this time, when the protective layer has an electrode, a silicon wafer layer having the electrode is formed.

  Moreover, the laminated body for solar cells of this invention can also be laminated | stacked with another general sealing material in a module process.

  An example of a process for producing a crystalline Si solar cell including the production of the laminate of the present invention is shown in FIG. In FIG. In the above first step, II. In the second step above, III. Corresponds to the above third step. Therefore, II. Or III. In this stage, the laminate of the present invention is manufactured. IV in FIG. The subsequent steps may be performed as necessary. For example, VII. And IX. This step may be performed only when the protective layer has an electrode. In addition, VIII. This step corresponds to a heat treatment for removing the protective layer and the adhesive layer.

  According to the present invention, a thin silicon wafer for solar cells is expected.

1. 1. Silicon wafer layer Protective layer (colored parts represent electrodes)

Claims (4)

A laminate for a solar cell having a silicon wafer layer and a protective layer. The laminate according to claim 1, further comprising protective layers on both sides or one side of the silicon wafer layer. The laminate according to claim 1 or 2, wherein the thickness of the silicon wafer layer is 50 µm or more and 250 µm or less. The laminated body in any one of Claims 1-3 in which the protective layer has an electrode.

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