JPH04249379A - 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 V-I characteristics based thereon. CONSTITUTION:After an insulating film 1b is formed on a stainless steel substrate 1a and rear electrodes 5a, 5b, 5c are formed thereon, an amorphous semiconductor layer consisting of each layer of P, I, N is formed uniform thereon through plasma CVD method. Thereafter, an incidence electrode (ITO film) which also works as a patterning mask of an a-Si layer is formed at a room temperature by vacuum evaporation using a metal mask, and then, the a-Si layer of a part whereon the ITO film is not formed is removed by etching to acquire incidence electrodes 3a, 3b and amorphous semiconductor layers 4a, 4b consisting of a-Si. Thereafter, Cu paste is printed and burned in a specified position to form connection electrodes 7a, 7b, 7c for connecting the rear electrode and the incidence electrode of an 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 a main part thereof. , 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. Usually, a light-transmitting insulating substrate is used, and a transparent conductive film such as indium tin oxide (ITO) is used as the first conductive unit layer formed on the substrate. 1st
The amorphous semiconductor unit layer formed on the conductor unit layer is
For example, it is a stack of amorphous silicon (hereinafter referred to as a-Si) consisting of a p layer, an i layer, and an n layer. The second conductor unit layer formed on the amorphous semiconductor unit layer to face the first conductor unit layer is composed of Cr, Al, C
The second conductor unit layer is usually configured to be connected to the first conductor unit layer of an adjacent photovoltaic element, and each photovoltaic element are connected in series. Note that a protective film is formed if necessary.

In the manufacturing process for obtaining such a photovoltaic device, the second conductive unit layer (
The method for connecting the first conductor unit layer (for example, the back electrode) of the adjacent photovoltaic element (for example, the incident electrode) is as follows: (1) 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; and (3) a method of cutting the a-Si layer with a laser beam. 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 in which patterning of an amorphous semiconductor layer can be carried out easily and precisely, and a VI obtained by the method.
An object of the present invention is to provide a photovoltaic device with good characteristics.

[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 Using the back electrode or the incident electrode, which is the second conductor formed as a film, as a mask for etching the a-Si layer,
The connection between the second conductor (back electrode or incident electrode) of each photovoltaic element and the first conductor (incident electrode or back electrode) of the adjacent photovoltaic element is performed in a separate process. By forming a connection electrode that does not cover the part of the upper surface of the electrode facing the first electrode, the above-mentioned problems in conventional photovoltaic devices can be solved, and the VI is lower than that of conventional photovoltaic devices. The inventors have discovered that a photovoltaic device with improved characteristics can be obtained, and 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. The first conductor layer of an adjacent photovoltaic element refers to the first conductor layer on the upper surface of the second conductor layer.
The amorphous semiconductor layer of the first conductor layer of the adjacent photovoltaic element is not formed on the upper surface of the photovoltaic element, covering the portion not facing the conductor layer and covering one side of the photovoltaic element. A photovoltaic device characterized in that the photovoltaic device is conductively connected by a connection electrode made of a layered conductive material formed so as to overlap the portion; secondly, the substrate is a translucent insulating substrate; The first conductor layer is a light-transmitting incident electrode, and the second conductor layer is a light-impermeable reflective electrode.
The above photovoltaic device; thirdly, the substrate is a non-transparent insulating substrate, the first conductive layer is a non-transparent reflective electrode, and the second conductive layer is transparent. The above-mentioned photovoltaic device is a light incident electrode; Fourth, after forming the first conductor unit layer group in a predetermined pattern on the substrate, a uniform thickness is formed over the entire upper surface of the pattern. An embodiment in which an amorphous semiconductor layer is formed as a continuous layer, and a second conductor unit layer group is provided on the semiconductor layer, each unit layer of which 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, the first conductor on the upper surface of each second conductor unit layer is A method for manufacturing a photovoltaic device is provided, which comprises forming a connecting electrode for covering a portion not facing a body unit layer and connecting this portion to a first conductive unit layer at an adjacent position.

[0016]

[Operation] In the manufacturing method of the present invention, the second conductor layer (back electrode or incident electrode) formed on the amorphous semiconductor layer, for example, the a-Si layer, is patterned by etching the a-Si layer. Since it is used as a mask for patterning, precise patterning can be performed without pattern shift or blurring. Foreign matter does not get mixed in between the a-Si layer and the back electrode layer (or the incident electrode). 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, in order to provide a connection electrode in a portion of the back electrode (or incident electrode) that does not face the incident electrode (or back electrode), the conductive layer placed farthest from the substrate is made a transparent electrode (i.e., incident electrode). It is also possible to create photovoltaic devices. The connection electrode can be formed by a printing method using copper paste, silver paste, or the like. Furthermore, 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. Since the photovoltaic device of the present invention is particularly suitable for manufacturing a type having an input electrode on the side opposite to the substrate, a similar type is shown as an example.

[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. An insulating film 1b was formed by forming SiO2 to a thickness of 10 μm on a stainless steel substrate 1a by a spray method. On top of that, 1200% Cr was applied using a metal mask using a vacuum evaporation method.
A film was formed to a thickness of A (angstrom) to form the first conductor layers (back electrodes) 5a, 5b, and 5c. On top of this, a
-Si layer is formed by plasma CVD method, p layer 200A,
The i layer was deposited at 6,000 amps, and the n layer was deposited at 200 amps. On the obtained a-Si layer, a second conductive layer (incident electrode) and a
- An ITO film that also serves as a mask for Si etching is deposited at room temperature using a metal mask using a vacuum evaporation method 90
The second conductor layer (incidence electrode) was formed to a thickness of 0A, and was immersed in a 10wt% NaOH solution at 60°C for 5 minutes to remove the a-Si in the part where the ITO film was not formed.
After etching the layer and dividing the a-Si layer into 4a and 4b, it was washed with water and dried. Next, Cu paste is printed on a predetermined location and baked at 150° C. for 10 minutes to form connection electrodes 7a, 7b for connecting the second conductor layer and the first conductor layer of an adjacent element. 7c was formed. moreover,
As the protective film 9a, a transparent resin was printed and heated at 150°C.
Baked for 0 minutes.

The photovoltaic device produced by the above method was irradiated with simulated sunlight using a solar simulator, and the VI characteristics were measured. As a result, a characteristic curve as shown by the solid line in FIG. 5 was obtained. For comparison, we also fabricated a photovoltaic device using the conventional method of simultaneously forming and patterning an a-Si layer using a metal mask, and measured it 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 is a photovoltaic device consisting of the same number of photovoltaic elements of the same size, compared to the photovoltaic device obtained by the conventional method. Even if there is, the VI characteristics are improved. In addition, the above measurement is
M (air mass) 1.0, incident intensity of simulated sunlight 10
In the case of 0 mW (milliwatt)/cm2, the cell area 1
cm2, cell gap 1.6mm, cell width 5mm,
These are measurement values performed on a photovoltaic device having 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]

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 manufacture a large-sized photovoltaic device in which a large number of photovoltaic elements are connected in series by narrowing the spacing between the photovoltaic elements. Furthermore, by providing a connection electrode in a portion of the second conductor unit layer that does not face the first conductor unit layer,
A conductor layer provided at a position far from the substrate surface can be used as an incident electrode. Along with the above patterning effect,
A photovoltaic device with improved VI characteristics than the conventional example can be obtained.

[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 measured VI characteristics of the photovoltaic device of the present invention and the conventional photovoltaic device, with solid lines indicating the present invention and the conventional photovoltaic device.
The dotted line is the characteristic curve of the conventional example.

[Explanation of symbols]

1 Glass substrate 1
a. Stainless steel substrate 1b
Insulating films 2a, 2b,
2c Input electrodes 3a, 3b Input electrodes 4, 4a, 4b which also serve as masks for patterning the a-Si layer Amorphous semiconductor layers 5a, 5b
, 5c Back electrodes 7a, 7b, 7c Connection electrodes 9, 9a Protective film A
Connection part B
Residues such as resist ink C
Holes or altered parts of 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 is defined as covering the upper surface of the second conductive layer that does not face the first conductive layer and covering one side surface of the photovoltaic element. By means of a connecting electrode made of a layered conductive material, which is formed so as to cover the part of the first conductive layer of the adjacent photovoltaic element that is not formed on the top surface of the amorphous semiconductor layer. A photovoltaic device characterized in that it is electrically conductively connected. 2. The substrate is a non-transparent insulating substrate,
2. The photovoltaic device according to claim 1, wherein the first conductive layer is a non-transparent reflective electrode and the second conductive layer is a transparent incident 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, a portion of the upper surface of each second conductive unit layer that does not face the first conductive unit layer is covered, and this portion is made adjacent to the top surface of the second conductive unit layer. A method for manufacturing a photovoltaic device comprising forming a connecting electrode for connecting with a first conductor unit layer at a position.