JPH01134976A - Manufacture of solar cell - Google Patents

Abstract

PURPOSE:To make a cut area of an optical semiconductor layer crystallized and highly conductive so as to make resistors connected between solar cell elements decrease and realize a solar cell of this design excellent in efficiency. CONSTITUTION:An inorganic insulator 33 is coated on a stainless substrate 32 and a stainless metal electrode 35 is formed on the insulator 33. And, an amorphous silicon semiconductor layer 36 is formed on the whole face as an optical semiconductor layer, and then the optical semiconductor layer 36 is cut by a laser beam and formed into two or more semiconductor regions 36 independent of each other. By these processes, the cut area of the amorphous silicon semiconductor is crystallized and made to be highly conductive, so that an electrical resistance between the adjacent electrodes can be decreased even if a transparent electrode is used as a series connection electrode of a series connection type solar cell. Therefore, a solar cell excellent in efficiency can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing solar cells, and particularly to a method for manufacturing series-connected solar cells.

[Conventional technology]

In recent years, methods of manufacturing series-connected solar cells by laser beam processing have been actively researched.

FIG. 2 is a cross-sectional view showing a series-connected solar cell manufactured on a transparent substrate by the solar cell manufacturing method disclosed in, for example, Japanese Patent Application Laid-Open No. 57-12568. In a battery, a series of tandem junction solar cell elements (20), (
2)) and (22).

Each tandem junction solar cell element (2υ), (2)), (
22) comprises a transparent conductive electrode strip (2) serving as the electrode on the side of light incidence and two semiconductor layers (3), (4) separated by a tunnel junction (5). The tandem junction solar cell elements (20), (2), and (22) are connected in series by a back electrode (6).

Next, a method for manufacturing the solar cell will be explained.

First, a transparent electrode (2) made of indium tin oxide, tin oxide, etc. is deposited on a transparent substrate (1) such as glass by a method such as vapor deposition or spunter, and the transparent electrode is marked with a neodymium YAG laser to make it transparent. A transparent electrode strip is formed on the substrate (1).

Next, an amorphous silicon semiconductor layer (
3) and (4) are deposited and a semiconductor layer is scored adjacent to and parallel to the markings on the transparent electrode (2). Next, a back electrode material such as titanium, aluminum, or indium is deposited on the semiconductor layer strip, and the back mt poles are scored with a laser to obtain a back electrode strip (1+) connecting each element in series.

Conventional series-connected solar cells manufactured using laser beams have the structure described above, but since glass is mainly used as the transparent substrate (1), the substrate may be damaged during the manufacturing process. However, there was a problem in that the product yield was reduced. For this reason, attempts have been made to manufacture series-connected solar cells using a steel plate or stainless steel plate coated with a heat-resistant resin such as polyimide resin or an insulating material such as glass enamel as a substrate.

FIG. 3 is a cross-sectional view of a conventional solar cell made by connecting in series on a substrate using a stainless steel plate as a base substrate and a polyimide resin as an insulating layer, as shown in, for example, Japanese Patent Application Laid-open No. 58-180069. . In the figure, (12) is a stainless steel plate, (13) is a polyimide resin with a thickness of 20 μm, and (14) is a stainless steel plate.
) is a lower electrode made of aluminum or chromium, etc., (15) is an amorphous silicon semiconductor film with a thickness of about 7UUOA, (
16) is a transparent electrode with a thickness of 1 (10 UA), and is formed so that the transparent electrode (L6) and the lower electrode ([4) with the negative part exposed] are electrically connected in series, and a plurality of light A solar cell is obtained in which power generation regions (23), (24), and (25) are connected in series.

[Problems to be Solved by the Invention] Conventional series-connected solar cells have the manufacturing method and structure described above. Therefore, when manufacturing using a transparent substrate such as glass as a substrate, Although it has good characteristics as a solar cell, it has the problem of being easily damaged and having poor productivity.Furthermore, when using an insulating substrate made of a stainless steel plate coated with an insulating material, as shown in Fig. 3, When a transparent electrode plays the role of a series electrode that connects adjacent photovoltaic regions in series, the transparent electrode, for example, indium tin oxide, has an electrical resistance that is two orders of magnitude higher than that of a metal electrode such as aluminum. (Also, the height difference between the transparent electrode and the lower electrode is approximately foooX, whereas the thickness of the transparent electrode that serves as the series electrode is only 1000mm thick.) Although the thickness of the transparent electrode to be deposited is extremely thin, there is a problem in that the series connection resistance increases and the characteristics of the solar cell are deteriorated.

This invention was made in order to solve the above-mentioned problems, and its purpose is to provide a method that can produce high-yield, highly efficient solar cells on a substrate that is difficult to break, such as metal. shall be.

[Means for solving problems]

In the method for manufacturing a solar cell according to the present invention, the step of dividing the optical semiconductor layer is performed in a non-oxidizing atmosphere by laser beam processing.

[Effect]

In the solar cell manufacturing method of this invention, the optical semiconductor layer around the laser beam processing part is crystallized by the heat of the laser beam and the electrical resistance value decreases, so the transparent electrode is used as the series connection electrode of the series connection type solar cell. Even in this case, the laser-processed wall surface of the optical semiconductor layer in contact with the transparent electrode crystallizes and becomes a good conductor, so that even if the transparent electrode film is thin, electrical connection between adjacent photovoltaic regions can be made successfully.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In Fig. 1, (32) is the base plate of stainless steel membrane, (3
3) is an inorganic insulator coated on the stainless steel substrate (32) with a thickness of about 20 μm. This base (3
2) On an insulating substrate (34) formed by coating an insulating material (33) thereon, a thickness of 2. u u A stainless steel film was deposited on the OA by sputtering, and neodymium Y with a wavelength of 1.06 μm was applied.
A plurality of independent stainless steel metal electrodes (35) are formed on an insulating substrate (34) in which a stainless steel film is cut in the air or in an inert atmosphere into a short fence shape with a beam diameter of 50 μm and a width of 8 using an AG laser. do. Next, the metal electrode (3
5) and the insulating substrate (34).
An amorphous silicon semiconductor layer (36) as an optical semiconductor layer having two PIN junctions is formed to a thickness of about euooX by plasma CVD, and then a beam diameter of 100 μm is formed using the second harmonic of a neodymium YAG laser with a wavelength of 0.53 μm. The semiconductor layer is cut adjacent to and parallel to the cutting groove of the metal electrode (35) to form a plurality of independent semiconductor regions (36).

The laser processing of the amorphous silicon semiconductor layer (36) is performed in a non-oxidizing atmosphere such as an inert gas or vacuum, and the cut surface of the amorphous silicon changes into an insulating oxide such as SiO□ by oxidation. to prevent The cut surface (360) of the amorphous silicon semiconductor layer (36) laser-processed in a non-oxidizing atmosphere was microcrystallized to a depth of approximately 50 μm due to the thermal influence of the laser beam. Next, a thickness of 20 mm made of indium tin oxide
After forming an ODA transparent electrode (37) on the semiconductor layer (36) by sputtering, predetermined locations of the transparent electrode are cut with a beam diameter of 20 μm using a laser beam to form a solar cell element (40) as a plurality of photoelectric conversion regions. ).

A series-connected solar cell (30) is obtained in which (41) and (42) are connected in series.

In the solar cell manufactured as described above, by performing the dividing process of the amorphous silicon semiconductor layer using a laser beam in a non-oxidizing atmosphere, the cut surface of the amorphous silicon semiconductor crystallizes and becomes a good conductor. There is.

Therefore, it has become possible to easily manufacture a highly efficient series-connected solar cell with a high yield and with reduced series-connection resistance between solar cell elements.

Note that the base (32), the insulating film (33), and the metal electrode (
35), the type of material used for the transparent electrode (37), the film thickness,
It goes without saying that the film-forming method is not limited to those described in the embodiments, and various applications, modifications, and changes are possible within the scope of the present invention. For example, instead of stainless steel, metals such as iron, nickel, and copper alloys, or ceramic materials may be used for the base body (32). When the base (32) has insulating properties, the insulating film (33) can be omitted.

In addition, sputtering technology used to form the metal electrode (35) or transparent electrode (37), plasma CVD i and laser beam processing used to form the amorphous silicon semiconductor layer (36) as an optical semiconductor layer, etc.
All known conventional techniques can be used as appropriate without any particular limitations.

〔Effect of the invention〕

As described above, according to the present invention, since the dividing process of the optical semiconductor layer is performed in a non-oxidizing atmosphere using a laser beam, it is possible to crystallize the cut surface of the optical semiconductor layer and make it a good conductor. This has the effect that the series connection resistance between solar cell elements can be reduced and a highly efficient series connection type solar cell can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the main parts of a series-connected solar cell manufactured by a solar cell manufacturing method according to an embodiment of the present invention, and FIGS. 2 and 3 are series-connected solar cells manufactured by a conventional method. FIG. 2 is a cross-sectional view of a solar cell. In the figure, (34) is the substrate, (35) is the metal electrode, (3
6) is an amorphous silicon semiconductor layer as an optical semiconductor layer, (37) is a transparent electrode, (40), (41), and (42) are photoelectric conversion regions, and (360) is a crystallized portion of the amorphous semiconductor.

Claims (2)

[Claims] (1) A step of sequentially laminating a metal electrode, an optical semiconductor layer having at least one PIN junction, and a transparent electrode on a substrate having an insulating surface, and a metal electrode formed by each of the above lamination steps. A plurality of photoelectric conversion regions electrically connected in series are formed on the substrate by dividing the optical semiconductor layer and the transparent electrode into a plurality of parts at predetermined positions in each lamination process. In the method for manufacturing solar cells,
A method for manufacturing a solar cell, characterized in that the step of dividing the optical semiconductor layer is performed using a laser beam in a non-oxidizing atmosphere. (2) The method for manufacturing a solar cell according to claim 1, wherein the optical semiconductor layer is an amorphous silicon semiconductor layer.