JPH03157976A - Photovoltaic device - Google Patents

Abstract

PURPOSE:To reduce damage at the time of forming a semiconductor layer, and effectively use light, by forming a photo detecting surface electrode as a metal electrode, and equipping the metal electrode with a light transparent part for transmitting an incident light. CONSTITUTION:A P-type semiconductor layer is formed on a substrate 1 via a photo detecting surface electrode layer 21, and the following are formed in order on the layer 31; a buffer layer 4, an I-type a-Si layer 5 and an N-type a-Si layer 6. A light transparent part 22 for transmitting an incident light is formed in the electrode layer 21 composed of Al. Hence the electrode layer 21 can be constituted without using a transparent conductive film, the sensitivity for short wavelength light is increased, and characteristics can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a photovoltaic device that converts light energy into electrical energy.

(b) Conventional technology A photovoltaic device whose photoactive layer is an amorphous silicon-based semiconductor layer with a pin semiconductor junction is already known.
Its basic configuration is shown in FIG.

In FIG. 6, (1) is a transparent insulating substrate made of glass or the like, and (2) is a transparent conductive film formed on the substrate (1). (3) is a p-type amorphous silicon (hereinafter referred to as a-3i) layer formed on the transparent conductive film (2), and (4) is formed on the p-type a-3i layer (3). The buffer layer (5) is an i-type a-3i layer formed on the buffer layer (4)l. (6) is an n-type a-5i layer,
(7) is a back electrode. By the way, tin oxide (SnO2) or indium tin oxide (ITO) is used for the above-mentioned transparent conductive film (2).

(c) Problems to be Solved by the Invention FIG. 7 is a characteristic diagram showing the relationship between wavelength and light absorption coefficient of a transparent conductive film made of SnO□ or ITO.

As shown in FIG. 7, since the transparent conductive film made of 5n02 or ITO has a large light absorption coefficient, it has the disadvantage that it reduces the output current of the photovoltaic device.

Also, JAPANESE JOURNAL OF AP
PLIED 1) HYSIC3Vo1.27. , No
,7. , July, 1988. pp, L1190
-Ll192 paper r Diffusion of C
on5tituent Atoms 1nP-type
As reported in a-3i: H/SnO□Interfaces J, the transparent conductive film made of 5n02 is easily reduced and is damaged during the formation of the p-type a-3i layer, resulting in a decrease in output. there were.

The present invention has been made to solve the above-mentioned difficulties, and an object of the present invention is to provide an electrode layer on the light-receiving surface side that does not cause a decrease in output.

(d) Means for Solving the Problems The present invention provides a photovoltaic device in which a light-receiving surface electrode layer, a semiconductor layer including a photoactive layer, and a back electrode layer are laminated on a light-transmitting insulating substrate serving as a light-receiving surface. The device is characterized in that the light-receiving surface electrode layer is formed of a metal electrode, and a light-transmitting portion that transmits incident light is formed in the metal electrode.

(E) Function Since the present invention does not use a transparent conductive film as the light-receiving surface electrode layer, damage during the formation of the semiconductor layer is reduced and light can be used effectively.

(F) Example Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 5.

Note that the same parts as in the conventional example are given the same reference numerals.

FIG. 1 is a cross-sectional view of a solar cell as a photovoltaic device of the present invention, and FIG. 2 shows a light-receiving surface electrode layer, which is the main part of the present invention.
FIG. 2(a) is a plan view, and the second section (b) is a sectional view.

In this figure, (1) is a light-transmitting insulating substrate made of glass or the like, and (21) is a metal electrode as a light-receiving surface electrode layer of the present invention formed on this substrate (1). In the example, a metal electrode (21) made of aluminum (A1)
A light transmitting portion (22) is formed to allow incident light to pass therethrough. The metal electrode (21) of this example is formed into a mesh shape in order to provide a transparent portion (22). As shown in FIG. 2, this metal electrode (21) made of A1 is formed so that the aperture ratio, that is, the area of the part without metal/total area is 90% or more.

(31) is connected to the substrate (1) via the light-receiving surface electrode layer (21).
This is a p-type semiconductor layer formed thereon, and a p-type amorphous silicon carbide (a-3iC) layer is formed, and polycrystalline is formed by laser annealing.

Al is used as this p-type dopant. The reason for using A1 is that A1 is excellent as a p-type dopant for crystalline SiC, and since AI is used as the metal electrode (21), even if this A1 is diffused by laser annealing etc. This is to avoid changing the characteristics of SiC.

(4) is a buffer liJ made of hydrogenated amorphous silicon carbide on this p-type semiconductor layer (31), (
5) is an i-type a-3i formed on the buffer layer (4).
Layer (6) is an n-type a-3i layer formed on the i-type a-3i layer (5). (7) is a back electrode made of A1.

Next, the film formation of each layer in this example will be specifically explained. Film formation was performed by plasma CVD method, and the film was formed on a substrate (1
) was placed in a reaction vessel, and each layer was formed under the formation conditions shown in Table 1.

(Margins below) Table 1 In this example, the p-type semiconductor layer (31) was formed by forming a p-type a-3i layer under the above-mentioned formation conditions, and then polycrystallized by laser annealing.

Next, we will discuss the present example formed under the above-mentioned conditions, the comparative example formed under the same conditions as the above-mentioned example except for the buffer layer, and the above-mentioned first example except that a transparent conductive film was used as the light-receiving surface electrode layer. A conventional example formed under the same conditions as those shown in the table was prepared, and the results of comparing each characteristic are shown in Table 2 and FIG.

Table 2 Conventionally, in solar cells using transparent conductive films, p-type S
It is known that a buffer layer is effective at the interface between iC and type 1 a-3i, but in the present invention, as shown in Table 2, the buffer layer (31) and type 1 a-5i layer (5 ) is shown to be effective in terms of the characteristics of the solar cell. Furthermore, an improvement in Isc can be seen as compared to the embodiment of the present invention and the conventional example.

FIG. 3 is a characteristic diagram showing the collection efficiency in each wavelength region of the embodiment of the present invention and the conventional example. As is clear from this figure, according to the present invention, the collection efficiency at the short wavelength 11 is improved.As shown in Table 2, due to this improvement in collection efficiency,
lsc has improved.

Further, under the formation conditions shown in Table 1, the buffer layer (4),
Example 2 of the present invention was created under the same formation conditions as in Table 1, except that the substrate temperature of the i-type a-3i layer (5) and the n-type a-5i layer (6) was set at a high temperature of 400°C. Conventional Example 2 was prepared under the same formation conditions by setting the semiconductor layer at the same location to a high temperature of 400° C., and the battery characteristics were measured. Table 3 shows the results. By the way, when the formation temperature is raised to -M, as shown in FIG. 4, the light absorption coefficient particularly in the long wavelength region increases, and an increase in current can be expected. However, in the conventional device, impurity diffusion from the transparent conductive film and the p-type a-8i layer increases, and as shown in Table 3, the characteristics are rather deteriorated, and no improvement in the characteristics can be expected. In contrast, in Example 2 of the present invention, no transparent conductive film is used, and the p-type semiconductor layer is also made of polycrystalline SiC formed by laser annealing, so the problem of diffusion is extremely small. Therefore, as shown in Table 3, compared to the formation at a substrate temperature of 200° C., Isc increases significantly, and it can be seen that the characteristics are improved.

(Margins below) Table 3 Next, a case where the present invention is applied to an ultraviolet sensor will be explained.

The formation conditions are basically the same as in Table 1, but each film thickness is different. The p-type semiconductor layer (31) has 50 people, and the l-type a-
The 8i layer (5) was set at 500 people. Moreover, quartz was used for the substrate (1).

FIG. 5 is a characteristic diagram showing the collection efficiency at reverse bias (-2V) of the ultraviolet sensor according to the present invention and the ultraviolet sensor formed in the same manner as the present invention except that a transparent conductive film was used.

As is clear from FIG. 5, it can be seen that the sensor according to the present invention has greatly improved sensitivity, especially in the short wavelength region, compared to the conventional example. This is due to the fact that the transparent conductive film has a high absorption coefficient in the short wavelength region, as shown in FIG.

In this manner, the present invention is effective as an ultraviolet sensor because it does not use a transparent conductive film.

In the above-described embodiments, the light-receiving surface electrode layer is formed of AI in a mesh shape, but the light-receiving surface electrode layer is not limited to the mesh shape, and may be formed in a line shape.

Further, as for the metal to be used, other than A1, Cr or the like having high heat resistance can also be used.

(g) As described in detail of the invention, according to the invention, the light-receiving surface electrode layer can be constructed without using a transparent conductive film, so that the short wavelength sensitivity can be improved and the characteristics can be improved. Furthermore, since it has excellent heat resistance, it is possible to improve the characteristics by using an amorphous semiconductor formed at a high temperature and having a high light absorption coefficient.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the photovoltaic device of the present invention.
Figure (a) is a plan view. Fig. 3 is a characteristic diagram showing the collection efficiency in each wavelength range for the present invention and the conventional example, Fig. 4 is a characteristic diagram showing the relationship between wavelength and light absorption coefficient at each substrate temperature, and Fig. 5 is a characteristic diagram for the present invention and the conventional example. FIG. 3 is a characteristic diagram showing the relationship between wavelength and light absorption coefficient when applied to a dorsal external ray sensor. FIG. 6 is a characteristic diagram showing a conventional photovoltaic device, and FIG. 7 is a characteristic diagram showing the relationship between wavelength and light absorption coefficient of a transparent conductive film. 2 Fig. 2 1 Fig. 1 1: Substrate 21: Metal electrode 31: P-type semiconductor layer 7: Back side electrode Sleeve writing (method) % formula % 1. Display of the incident 1999 Patent Application No. 297159 2. Name of the invention Photovoltaic device 3 Relationship with the case of the person making the amendment Patent applicant name f188 + Sanyo Electric Co., Ltd. 4 Agent address (12 Yamato Building, 1-6 Tenjin Nishimachi, Kita-ku, Osaka 530) Building No. 3, Floor 307, No. 7, page 11, line 20 to page 12, line 10 of the statement of contents of the amendment are amended as follows. FIG. 1 is a sectional view showing the photovoltaic device of the present invention, and FIG. 2 shows the light-receiving surface electrode layer, which is the main part of the present invention.
2 is a plan view, and FIG. 2(b) is a sectional view. Fig. 3 is a characteristic diagram showing the collection efficiency in each wavelength range for the present invention and the conventional example, Fig. 4 is a characteristic diagram showing the relationship between wavelength and light absorption coefficient at each substrate temperature, and Fig. 5 is a characteristic diagram for the present invention and the conventional example. FIG. 3 is a characteristic diagram showing the relationship between wavelength and light absorption coefficient when applied to an ultraviolet sensor. Figure 6 is a characteristic diagram showing a conventional photovoltaic device;
The figure is a characteristic diagram showing the relationship between wavelength and light absorption coefficient of a transparent conductive film. 5. Date of amendment order (dispatch mortar) February 27, 1990 or later

Claims (1)

[Claims] (1) A photovoltaic device in which a light-receiving surface electrode layer, a semiconductor layer including a photoactive layer, and a back electrode layer are laminated on a light-transmitting insulating substrate serving as a light-receiving surface, wherein the light-receiving surface electrode layer 1. A photovoltaic device characterized in that it is formed of a metal electrode, and a light-transmitting part that allows incident light to pass through the metal electrode is formed.