JPH06268241A - Thin-film solar cell and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a thin-film solar cell composed of unit cells connected together in series, wherein a patterning operation through which layers are patterned with an expensive apparatus or a patterning opera tion which may cause damage to an amorphous semiconductor layer can be dispensed with. CONSTITUTION:Through-holes 6 are bored in a polymer film 1 at its edge in a line, a third electrode 5 is formed around the rear opening of the hole 6, a first electrode layer 2, an amorphous semiconductor layer 3, and a second electrode layer 4 are laminated on the front side of the film 1, the extension of the third electrode layer 5 is made to overlap the extension of the first electrode layer 2 inside the through-hole 6, and both the extensions are connected together. Then, the film 1 is separated in a lengthwise direction into unit cells 7, and the unit cell 7 is pasted on the adjacent unit cell 7 making the edge surface of the second electrode layer 4 of the former overlap the third electrode 5 of the later.

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 in which unit cells each having a semiconductor thin film formed on a flexible insulating substrate as a photoelectric conversion layer are connected in series, and a method for manufacturing the same.

[0002]

2. Description of the Related Art An amorphous semiconductor film such as amorphous silicon formed by glow discharge decomposition of a raw material gas is a vapor phase growth, so that it is easy to increase the area and is expected as a photoelectric conversion film for a low-cost solar cell. ing. As a well-known method for extracting electric power from such a large area thin film solar cell, the thin film solar cell is divided into a plurality of unit cells on one substrate, and these are connected in series,
There is a series-connected solar cell as shown in FIG. This is a glass or polymer film or the like, on the insulating substrate 10, the first electrode 21, 22, 23-is formed in a strip shape, the amorphous semiconductor layer region 31, which is a photovoltaic generation portion, thereon.
32, 33-, and then second electrodes 41, 42, 43- are formed. A combination of the first electrode 21, the amorphous semiconductor layer 31, and the second electrode 41, a combination of the first electrode 22, the amorphous semiconductor layer 32, and the second electrode 42, and the like form each unit cell. Then, the pattern of both electrodes and the amorphous semiconductor layer is formed so that the first electrode of one unit cell, for example, 22 has a structure in which the second electrode of an adjacent unit cell, for example, the edge of 41 is in electrical contact. Then, the unit cells are connected in series. The formation of such a series-connected solar cell is most generally performed by depositing each layer on the entire surface and then patterning by a laser scribing method each time.

There are two main reasons for adopting such a series connection structure in a large area solar cell. One is to obtain a high output voltage with one solar cell. Another more basic reason is the purpose of reducing Joule losses in transparent electrodes. That is, when a solar cell is formed on the entire surface by one unit cell without forming a series connection structure, the generated carriers are generated in the first electrode and the second electrode up to the lead wire extraction portion provided at the solar cell end. It will move over a long distance. In general, the light incident side of the first and second electrodes is a transparent electrode, and the opposite side is a metal electrode. Metal electrodes generally have low resistance,
Therefore, the disappearance of Joule due to the current flowing through the metal electrode can be ignored. However, the transparent conductive film as the material of the transparent electrode has a sheet resistance of 5 to 30 Ω / □ and a relatively large resistance, and Joule loss due to the current flowing through the transparent electrode layer cannot be ignored. Therefore, in the prior art, it is general to divide a large-area solar cell into a plurality of strip-shaped unit cells and set the width of the unit cell to about 5 to 20 mm.

[0004]

However, such a thin film solar cell has the following problems. (1) An expensive patterning device such as a laser scribing device is required for patterning. (2) Since the film forming process of the first electrode, the amorphous semiconductor layer, and the second electrode and the patterning process are alternated, the process becomes complicated, for example, it is difficult to form a film forming apparatus for three layers in-line.

(3) After forming the amorphous semiconductor layer and before forming the second electrode, a patterning step of the amorphous semiconductor layer is performed, during which the surface of the amorphous semiconductor layer is easily damaged, performance defects such as short circuit occur, and the manufacturing yield Lowering occurs. An object of the present invention is to solve the above-mentioned problems, to connect a plurality of unit cells having a flexible insulating substrate in series, without requiring an expensive device, and enabling in-line flexibility of film formation of each layer. Another object of the present invention is to provide a thin film solar cell that can be manufactured without fear of damage to the amorphous semiconductor layer, and a manufacturing method thereof.

[0006]

To achieve the above object, the present invention provides a unit in which a first electrode layer, an amorphous semiconductor layer, and a second electrode layer are laminated on the surface of a flexible insulating substrate. In a thin film solar cell in which a plurality of cells are connected in series, a through hole is formed in an edge of a flexible insulating substrate, and the third electrode layer provided around the through hole on the back surface of the substrate has the same unit. The first electrode layer of the cell and the extension of both electrode layers on the inner wall of the through hole are overlapped to electrically connect, and the second electrode layer of the adjacent unit cell and the edge of both unit cells are overlapped to electrically connect. Be connected to each other. Then, the terminal plates are respectively overlaid on the second electrode layer on the edge of the unit cell at one end and the third electrode layer on the edge of the unit cell at the other end of the plurality of the plurality of edge parts which are arranged in a line. What has been done is effective. It is also effective that the second electrode layer is not provided above the through hole peripheral portion. The method of manufacturing such a thin film solar cell is such that after forming through holes arranged in the longitudinal direction of the substrate at the edges of the flexible insulating substrate, the third electrode layer and the substrate surface are provided on the back surface of the substrate around the through holes. A first electrode layer, an amorphous semiconductor layer, and a second electrode layer are formed in this order on the top, the extension of the third electrode layer and the extension of the first electrode layer are overlapped in the through hole, and then the substrate is set in the longitudinal direction. The unit cell is divided into a plurality of unit cells to form a plurality of unit cells, and the edge portion of the second electrode layer of one unit cell and the third electrode layer of another unit cell are sequentially stacked.

[0007]

[Function] Of the first electrode layer, the amorphous semiconductor layer and the third electrode layer formed before the division into unit cells,
Since it is not necessary to pattern the first electrode layer and the amorphous semiconductor layer, damage in the patterning process of the amorphous semiconductor layer is eliminated, and in-line film formation of these three layers is possible. Further, the connection between the first electrode layer and the third electrode layer on the back surface is automatically made by overlapping the extended portions of both layers between the through holes during film formation from both surfaces. And
Since the substrate is flexible, it is easy to stack each unit cell and bring it into close contact with the edge of the second electrode layer and the third electrode of the adjacent unit cell, and a series connection structure can be easily obtained. .

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In order to manufacture a thin film solar cell according to an embodiment of the present invention, first, as shown in FIG. 1 (a), a polyethylene phthalate film having a thickness of 100 μm, a width of 18 mm and a length of 100 m is sequentially drawn from a roll body. Small holes 6 are formed in one edge of the polymer film 1 at intervals of 20 mm by a CO ₂ laser or a punching device. Then, A- in FIG.
As shown in FIG. 1 (b) which is a sectional view taken along the line A, the third electrode 5 is formed in the small hole 6 from the Al thin film sputter-deposited with a thickness of 300 nm on one surface of the polymer film 1 as the substrate. Form. Then, on the surface of the film substrate 1 opposite to the electrode 5,
A transparent first electrode layer 2 made of ZnO formed by a sputtering method, an amorphous silicon layer 3 formed by a plasma CVD method, and a second electrode layer 4 made of an Ag thin film formed by a sputtering method, respectively. 1μm, 500nm, 100n
Sequentially formed to a thickness of m. Of these, when forming the second electrode layer 4, a method such as using a mask is used so as not to cover the upper portion of the small hole 6 as illustrated. As a result, as shown in FIG. 3, the third electrode layer 5 and the second electrode layer 2 are formed on the inner wall of the small hole 6.
Since the amorphous silicon layer 3 is attached and extends to the surface on the opposite side, the first electrode layer 2 and the third electrode layer 5 come into contact with each other and become electrically conductive. However, the second electrode layer 4
Does not cover the upper part of the small hole 6 and therefore does not extend to the opposite surface and short-circuit with the third electrode layer 5.

Next, the film 1 is cut into a predetermined length and divided into unit cells, and as shown in FIG. 1 (c), the edge portion of the small hole 6 of one unit cell 7 is opened. The third electrode 5 of another unit cell 7 is placed on top of it. Such connection of the unit cells 7 is performed by adhering the unit cells 7 on the surface protective film 9 with an adhesive as shown in FIGS. 4 (a) and 4 (b). At this time, the film 1 of the substrate
Is easily deformed, the second electrode layer 4 and the third electrode layer 5
Can be closely attached. Then, instead of the unit cells, the terminal plates 9 are overlapped at both ends to form a serial connection type structure. Although not shown, the back surface protective film is covered on this and laminated integrally to complete the solar cell module.

In this embodiment, a small hole 6 is provided at the end of the film substrate 1, and the first electrode layer and the third electrode layer are formed on both surfaces of the small hole 6 by sputtering to form the first electrode and the first electrode layer. Three electrodes are contacted and electrically connected, but in short, at the end of the surface of the flexible insulating substrate opposite to the first electrode,
Any other method such as a screen printing method may be used as long as the third electrode electrically connected to the first electrode can be provided.

[0011]

According to the present invention, the uppermost second electrode layer of one unit cell is overlapped with the first electrode layer of the adjacent unit cell and the third electrode connected on the inner wall of the substrate through hole. The following effects were obtained by forming the serial connection structure. (1) An expensive patterning device such as a laser scribing device is unnecessary for patterning.

(2) The amorphous semiconductor layer and the second electrode layer can be continuously formed on a long film drawn from a roll body, and damage to the surface of the amorphous semiconductor layer in the conventional patterning process of the amorphous semiconductor layer can be prevented. Hard to occur. (3) The output current of the solar cell can be freely changed by the cut-out length of the tape-shaped unit cell and the output voltage can be changed according to the number of stages that are stacked in series, and it can easily correspond to various current and voltage specifications. It is possible.

[Brief description of drawings]

FIG. 1 shows a thin film solar cell according to an embodiment of the present invention, (a)
Is a plan view of the substrate film, (b) is a cross-sectional view taken along the line AA of (a), and (c) is a cross-sectional view of the unit cell overlapping portion.

FIG. 2 is a cross-sectional view of a conventional thin film solar cell.

FIG. 3 is a sectional view of a through hole portion of the thin film solar cell of FIG.

FIG. 4 shows a thin film solar cell module according to an embodiment of the present invention, (a) is a plan view, (b) is a sectional view taken along line BB of (a).

[Explanation of symbols]

 1 Polymer Film Substrate 2 First Electrode Layer 3 Amorphous Silicon Layer 4 Second Electrode Layer 5 Third Electrode Layer 6 Small Hole 7 Unit Cell 8 Surface Protection Film 9 Terminal Board

Claims (4)

[Claims] 1. A flexible insulating substrate in which a plurality of unit cells formed by laminating a first electrode layer, an amorphous semiconductor layer, and a second electrode layer on a surface of a flexible insulating substrate are connected in series. A through-hole is formed in the edge of the substrate, and the third electrode layer provided around the through-hole on the back surface of the substrate is the first electrode layer of the same unit cell and an extension of both electrode layers on the inner wall of the through-hole. Are connected by overlapping, and the second electrode layer of an adjacent unit cell is connected by overlapping the edges of both unit cells. 2. A second electrode layer at the edge of the unit cell at one end and a third electrode layer at the edge of the unit cell at the other end out of a plurality of the plurality of which are arranged in a line with the edges overlapping each other. The thin-film solar cell according to claim 1, wherein the terminal plates are stacked. 3. The thin film solar cell according to claim 1, wherein the second electrode layer is not provided above the peripheral portion of the through hole, and the method for manufacturing the thin film solar cell. 4. A through hole arranged in the longitudinal direction of the substrate is formed in an edge portion of the flexible insulating substrate, a third electrode layer is provided around the through hole on the back surface of the substrate, and a first electrode is provided on the front surface of the substrate in this order. A layer, an amorphous semiconductor layer, a second electrode layer is formed, and the extension of the third electrode layer and the extension of the first electrode layer are overlapped in the through hole,
Next, the substrate is divided in the longitudinal direction to form a plurality of unit cells, and the edge portion of the second electrode layer of one unit cell and the third electrode layer of the other unit cell are sequentially stacked. The method for producing a thin film solar cell according to claim 1, 2, or 3.