JPH04249378A - Photovoltaic device and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a manufacture method of a photovoltaic device which can carry out patterning of an amorphous semiconductor layer readily and precisely and a photovoltaic device of excellent VI characteristics based thereon. CONSTITUTION:After a transparent conductive film is formed on a glass substrate 1, specified incidence electrodes 2a, 2b, 2c are formed by resist patterning and etching. After an a-Si layer which consists of each layer of P, I and N is formed thereon by plasma CVD method, a Cr layer which works as both a rear electrode and a mask of the a-Si layer is formed at a room temperature by vacuum evaporation using a metal mask. Thereafter, the a-Si layer in a part whereon the Cr layer is not formed is removed by etching to acquire rear electrodes 6a, 6b and amorphous semiconductor layers 4a, 4b consisting of a-Si. Then, Cu paste is printed and burnt at a specified position to form connection electrodes 8a, 8b, 8c for connecting the rear electrode and an incidence electrode of adjacent element.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic device in which a plurality of photovoltaic elements are regularly arranged on an insulating substrate, and a method for manufacturing the same.

0002

2. Description of the Related Art A photovoltaic device is known in which a plurality of photovoltaic elements are regularly arranged on a substrate. Each photovoltaic element of the device includes a first conductive unit layer formed in contact with the substrate surface, and an amorphous semiconductor unit layer formed on the first conductive unit layer in its main part. , a second conductor unit layer is formed on the amorphous semiconductor unit layer so as to face the first conductor unit layer, and the substrate and each layer are each made of the following materials. That is, first, the substrate is made of a light-transmitting insulating substrate such as glass, or a non-light-transmitting substrate such as metal, on which an insulating film is formed as necessary. In the device of the present invention, a light-transmitting insulating substrate is usually used, and a transparent conductive film such as indium tin oxide (ITO) is used as the first conductive unit layer formed on the substrate. The amorphous semiconductor unit layer formed on the first conductor unit layer is a stack of amorphous silicon (hereinafter referred to as a-Si) consisting of, for example, a p layer, an i layer, and an n layer. The second conductor unit layer formed on the amorphous semiconductor unit layer so as to face the first conductor unit layer is made of a conductive metal such as Cr, Al, Cu, etc. The conductor unit layer is configured to be connected to the first conductor unit layer of an adjacent photovoltaic element, and each photovoltaic element is connected in series. Note that a protective film is formed if necessary.

In the manufacturing process for obtaining such a photovoltaic device, the first conductive unit layer of the photovoltaic element adjacent to the back electrode, which is the second conductive unit layer of each photovoltaic element, is The method for connecting the input electrode is as follows:
(1) A method of patterning the a-Si layer using a metal mask during film formation, (2) A method of patterning the a-Si layer by etching using resist patterning, (3) A method of cutting the a-Si layer with laser light. There are three examples: These details are as explained below.

Conventional method for manufacturing a photovoltaic device (1)
FIG. 2 is a sectional view of a photovoltaic device according to the method (1) above. In this method, a glass substrate 1 is prepared, and a uniform thickness of ITO is deposited on the entire surface of the substrate by vacuum evaporation.
Forms a film. Next, after applying a resist to obtain a predetermined pattern, unnecessary portions of the ITO film are removed by etching with hydrochloric acid or the like. Next, the applied resist is removed to obtain a first conductor pattern made of an ITO film in a predetermined pattern, that is, incident electrodes 2a, 2b, and 2c.

Next, a is provided with openings in a predetermined pattern.
- Place a metal mask for forming the Si layer on the first surface of the substrate.
After forming an a-Si layer consisting of a p layer, an i layer and an n layer to a predetermined thickness by plasma CVD method, the metal mask is removed and the a-Si layer with a predetermined pattern is placed on top of the conductor pattern. Amorphous semiconductor layers 4a and 4b are obtained.

Next, a metal mask for forming a second conductive layer is placed on the a-Si pattern on the substrate in the same manner as above, and a Cr layer, for example, is formed to a predetermined thickness by vacuum evaporation. , remove the metal mask, and remove the second mask of the predetermined pattern.
Back electrodes 5a, 5b, and 5c are obtained as conductors. Furthermore, if necessary, a protective film 9 is formed using a resin or the like by a screen printing method or the like.

[0007] Conventional method for manufacturing a photovoltaic device (2)
FIG. 3 is a sectional view of a photovoltaic device according to method (2) above. The formation of an amorphous semiconductor pattern in this method is as follows, and the rest is the same as in the first method. That is, after forming an a-Si layer consisting of a p layer, an i layer, and an n layer to a uniform predetermined thickness over the entire upper surface of the first conductor pattern by plasma CVD method, a resist is applied in a predetermined pattern. By performing etching to remove unnecessary portions of a-Si, and then removing the resist, amorphous semiconductor layers 4a and 4b made of a-Si having a predetermined pattern are obtained.

Conventional method for manufacturing a photovoltaic device (3)
FIG. 4 is a sectional view of a photovoltaic device according to method (3) above. The formation of an amorphous semiconductor pattern in this method is as follows, and the rest is the same as in the first method. That is, after forming an a-Si layer consisting of a p layer, an i layer, and an n layer to a predetermined uniform thickness over the entire surface of the first conductor pattern by plasma CVD, or after forming the a-Si layer to a predetermined uniform thickness, After forming a second conductor layer in a predetermined pattern on the a-Si layer, a part of the a-Si or each of the a-Si and the second conductor layer is irradiated with laser light at a predetermined location. A portion is removed and a conductor is encapsulated in the removed portion to obtain an amorphous semiconductor layer 4 made of a-Si having a predetermined pattern. C in the same figure shows a hole or altered part formed by laser patterning.

[0009]

However, the above prior art has the following problems.

[0010] In the above manufacturing method (1), when forming an amorphous semiconductor film, the temperature must be high, so the pattern may be misaligned or blurred due to factors such as thermal expansion of the metal mask, resulting in poor pattern accuracy. For example, as shown in FIG. 2, the a-Si spreads laterally, the connection part A between the incident electrode 2b and the back electrode 5b becomes narrow, and the electrical characteristics deteriorate. In addition, because the strength of the metal mask must be kept constant, it is necessary to narrow the spacing between the photovoltaic elements by narrowing the pattern spacing, and to obtain a large photovoltaic device consisting of multiple photovoltaic elements. becomes difficult.

In the manufacturing method (2), as shown in FIG. 3, when removing the resist used for patterning the a-Si layer, the surfaces of the a-Si layers 4a and 4b and the back electrodes 5a and 5b are removed. , 5c, and the connection between the incident electrode 2b and the back electrode 5b, foreign matter, such as residue B of resist ink, is likely to exist and deteriorate the electrical characteristics, so cleaning is required to remove it. This requires additional steps and makes the process complicated.

[0012] In the manufacturing method (3), since a laser is used, as shown in FIG.
It is difficult to manufacture a large photovoltaic device because the manufacturing cost is high and it is difficult to adjust the laser intensity. Not suitable. Furthermore, since the conductor is enclosed in the C section, the connection resistance increases.

Therefore, an object of the present invention is to provide a method for manufacturing a photovoltaic device that allows easy and precise patterning of an amorphous semiconductor layer, and a photovoltaic device with good VI characteristics obtained thereby. It is about providing.

[0014]

[Means for Solving the Problems] In order to achieve the above object, the present inventors have carefully studied the problems in the conventional manufacturing method and have found that The back electrode, which is the second conductor, is made of a-Si.
The second conductor (back electrode) of each photovoltaic element is connected to the first conductor (incident electrode) of the adjacent photovoltaic element in a separate step. We have discovered that by forming connection electrodes, the above-mentioned problems in conventional photovoltaic devices can be solved, and a photovoltaic device with improved VI characteristics than conventional photovoltaic devices can be obtained. We have arrived at the present invention.

That is, the present invention firstly provides a photovoltaic device in which a plurality of photovoltaic elements are formed on a substrate in a predetermined pattern, each photovoltaic element being formed in contact with the substrate. an amorphous semiconductor layer formed to cover the main part of the upper surface of the first conductor layer and have one end in contact with the substrate; It has a three-layer structure consisting of a second conductor layer formed to cover the entire portion facing the conductor layer, and the second conductor layer of each photovoltaic element and the second conductor layer formed to cover the entire portion facing the conductor layer. A first conductive layer of an adjacent photovoltaic element is a first conductive layer of an adjacent photovoltaic element that covers almost the entire upper surface of the second conductive layer and one side of the photovoltaic element. A light characterized in that the amorphous semiconductor layer of the first conductor layer is conductively connected by a connecting electrode made of a layered conductive material formed so as to overlap the portion not formed on the upper surface of the amorphous semiconductor layer. Electromotive force device; secondly, the substrate is a transparent insulating substrate, the first conductive layer is a transparent incident electrode, and the second conductive layer is a non-transparent reflective substrate; The photovoltaic device described above is an electrode; third, after forming a first conductive unit layer group in a predetermined pattern on a substrate, a non-conductive layer is formed as a continuous layer with a uniform thickness over the entire upper surface of the pattern. A crystalline semiconductor layer is formed, and a second conductor unit layer group is formed on the semiconductor layer in a pattern in which each unit layer faces each unit layer constituting the first conductor pattern. After etching and patterning the amorphous semiconductor layer by using the formed second conductor pattern as a resist, each second conductor unit layer is replaced with a first conductor unit at an adjacent position. A method of manufacturing a photovoltaic device is provided, which comprises forming a connecting electrode for connecting to a layer.

[0016]

[Operation] In the manufacturing method of the present invention, the second conductor layer (usually
Since the back electrode (which becomes the back electrode) is used as a mask for patterning the a-Si layer by etching, precise patterning can be performed without pattern displacement or blurring. Foreign matter does not get mixed in between the a-Si layer and the back electrode layer. Furthermore, since the patterning is performed by a low-temperature process using etching, the spacing between elements can be narrowed, making it possible to increase the size by using a plurality of elements. Furthermore, by providing a connection electrode on almost the entire surface of the back electrode, a good connection with low resistance can be obtained between the first conductor layer (incident electrode) of an adjacent element. The connection electrodes can be formed by a printing method using copper paste, silver paste, or the like. Also,
The method is not limited to the printing method, and a film of chromium, aluminum, nickel, ITO, etc. may be formed by a sputtering method, a vapor deposition method, or the like. The material of the connection electrode may be the same as or different from that of the second conductor.

The present invention will be further explained below with reference to Examples.

[0018]

Embodiment 1 FIG. 1 is a sectional view of a photovoltaic device according to an embodiment of the present invention, and the following description will be made with reference to this figure. 800A of ITO was deposited on the glass substrate 1 by vacuum evaporation method.
The film was formed to a thickness of (Angstrom). A resist with a predetermined pattern is printed on this and etched with hydrochloric acid.
By removing the resist, a predetermined pattern of incident electrodes 2a, 2b is formed.
, 2c was obtained. On top of this, a-Si was deposited by plasma CVD to form a p layer of 200A, an i layer of 6,000A, and an n layer.
200A was deposited. On the obtained a-Si layer, a Cr layer which also serves as a back electrode and a mask for a-Si etching is formed by vacuum evaporation at room temperature using a metal mask.
It was formed to a thickness of 1,200A. This at 60℃, 10w
It was immersed in a t% NaOH solution for 5 minutes to etch the a-Si portions where the Cr layer was not formed. after that,
After washing with water and drying, back electrodes 6a and 6b were obtained. Next, Cu paste was printed at predetermined locations as connection electrodes 8a, 8b, and 8c, and baked at 150° C. for 10 minutes. Furthermore, a resin was printed as a protective film 9 and baked at 150° C. for 10 minutes.

The photovoltaic device produced by the above method was irradiated with simulated sunlight using a solar simulator, and its VI characteristics were measured. As a result, a characteristic curve as shown by the solid line in FIG. 5 was obtained. For comparison, a photovoltaic device was also fabricated using the conventional method of simultaneously forming and patterning an a-Si layer using a metal mask, and measurements were performed under the same conditions as above. A curve shown by the dotted line was obtained.

As can be seen from FIG. 5, the photovoltaic device of the present invention has improved VI characteristics compared to the photovoltaic device obtained by the conventional method, even if the device has a pattern of the same size. are doing. Note that the above measurements were performed using AM (air mass) 1.
0, the incident intensity of simulated sunlight is 100 mW (milliwatt)/cm2, and these are the measured values for a photovoltaic device with a cell area of 1 cm2, a cell gap of 1.6 mm, a cell width of 5 mm, and a number of cells of 4 cells. .

[0021]

[Example 2] As a connection electrode, 1,200A was formed by patterning Al using a metal mask method using vacuum evaporation.
A photovoltaic device was manufactured in the same manner as in Example 1 except that the film was formed to a thickness of . A photovoltaic device having good characteristics similar to those of Example 1 was obtained.

[0022]

[Example 3] As a connection electrode, 1,200A was used while patterning Cr using a metal mask method using vacuum evaporation.
A photovoltaic device was manufactured in the same manner as in Example 1 except that the film was formed to a thickness of . A photovoltaic device having good characteristics similar to those of Example 1 was obtained.

[0023]

[Example 4] Stainless steel substrate was sprayed with S.
An insulating film of iO2 was formed to a thickness of 10 μm. in addition,
By vacuum evaporation method, 1,2 Cr is deposited using a metal mask.
The film was formed to a thickness of 0.00 A. On top of this, a-Si was deposited by plasma CVD to form a p layer of 200A and an i layer of 6,000A.
A, n-layer 200A, deposited. On top of this, ITO, which also served as a back electrode and a mask, was formed to a thickness of 900 Å by vacuum evaporation at room temperature using a metal mask. This was immersed in a 10 wt% NaOH solution at 60°C for 5 minutes, and the a-S
i was etched. Thereafter, after washing with water and drying, ITO was deposited as a connection electrode by vacuum evaporation at room temperature using a metal mask to form a transparent conductive film having a thickness of 900 Å corresponding to 8b in FIG. Furthermore, a resin was printed as a protective film and baked at 150°C for 10 minutes. A photovoltaic device having good characteristics similar to those of Example 1 was obtained.

[0024]

As explained above, in the photovoltaic device of the present invention, the amorphous semiconductor layer is not patterned in a high-temperature environment. patterning can be performed easily and precisely, and it is also possible to narrow the spacing between the photovoltaic elements and manufacture a large-sized photovoltaic device in which a large number of photovoltaic elements are connected in series. In addition, since the connection electrode can be provided on almost the entire surface of the second conductor unit layer (back electrode), good connection can be achieved between the first conductor unit layer (incidence electrode) of the adjacent photovoltaic element. can be obtained, and a photovoltaic device can be obtained which has not only the above-mentioned patterning effect but also improved VI characteristics compared to the conventional example.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a photovoltaic device in one embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional photovoltaic device in which an a-Si layer is patterned using a metal mask.

FIG. 3 is a cross-sectional view of a conventional photovoltaic device in which an a-Si layer is patterned with a resist.

FIG. 4 is a cross-sectional view of a conventional photovoltaic device in which an a-Si layer is patterned by laser light.

FIG. 5 is a graph showing the VI characteristics of the photovoltaic device of the present invention and the conventional photovoltaic device, with solid lines indicating the present invention,
The dotted line is the characteristic curve of the conventional example.

[Explanation of symbols]

1 Glass substrate 2
a, 2b, 2c incident electrode (transparent conductive film) 4, 4
a, 4b amorphous semiconductor layers 5a, 5b, 5c
Back electrodes 6a, 6b Back electrodes 8a, 8b,
8c Connection electrode 9 Protective film A
Connection part B
Residues of resist ink, etc. Holes or altered areas from laser patterning

Claims (3)

[Claims] 1. A photovoltaic device in which a plurality of photovoltaic elements are formed in a predetermined pattern on a substrate, wherein each photovoltaic element has a first conductive layer formed in contact with the substrate. an amorphous semiconductor layer formed to cover the main part of the upper surface of the first conductor layer and have one end in contact with the substrate; and an amorphous semiconductor layer that faces the first conductor layer on the upper surface of the amorphous semiconductor layer. It has a three-layer structure consisting of a second conductor layer formed to cover the entire part of the photovoltaic element, and the second conductor layer of each photovoltaic element;
The first conductive layer of the photovoltaic element adjacent to this means that the first conductive layer of the adjacent photovoltaic element covers almost the entire upper surface of the second conductive layer and covers one side of the photovoltaic element. The amorphous semiconductor layer of the first conductor layer is conductively connected by a connection electrode made of a layered conductive material formed so as to overlap the portion not formed on the upper surface of the amorphous semiconductor layer. photovoltaic device. 2. The substrate is a light-transmitting insulating substrate, the first conductive layer is a light-transmitting incident electrode, and the second
2. The photovoltaic device according to claim 1, wherein the conductive layer is a non-transparent reflective electrode. 3. After forming a first conductor unit layer group in a predetermined pattern on a substrate, an amorphous semiconductor layer is formed as a continuous layer with a uniform thickness over the entire upper surface of the pattern, and A second conductor unit layer group formed on the layer is formed in a pattern in which each unit layer faces each unit layer constituting the first conductor pattern. After etching and patterning the amorphous semiconductor layer by using the body pattern as a resist, forming connection electrodes for connecting each second conductor unit layer to the first conductor unit layer at an adjacent position. A method for manufacturing a photovoltaic device, comprising: