JP2000223724A - Amorphous silicon solar battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase an effective surface area of a solar battery against a substrate area to increase the current output by forming semi-spherical dimples on the surface of a glass substrate to be used. SOLUTION: Amorphous silicon solar battery element has such a structure that a transparent electrode film 02, an amorphous silicon film 03, and a metal electrode film 04 are stacked on a glass substrate 01 formed with semi-spherical dimples. If necessary, a protective film 05 can be formed on the metal electrode film 04. The use of the glass substrate 01 having dimples increases the current output by about 1.2 times compared with a case wherein a flat glass substrate is used. By forming the semi-spherical dimples on the glass substrate 01, an effective surface area is increased, thereby increasing the current output. This effect is not one derived from the material, shape, etc., of the transparent electrode 02 and therefore the transparent electrode can be of any shape and material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solar cell having an electrode film and an amorphous silicon film laminated on a glass substrate.

[0002]

2. Description of the Related Art An amorphous silicon solar cell in which a transparent electrode film, an amorphous silicon film, and a metal electrode film are further laminated on a glass substrate is well known. In addition, the amorphous silicon solar cell having the above structure has a texture structure for the purpose of confining incident light.
A structure using a transparent electrode made of SnO2 is also well known. In particular, the use of a SnO2 transparent electrode having a texture structure is an effective means for improving the utilization efficiency of incident light and improving the current output. In general, a textured SnO2 electrode is formed by growing crystal grains having a diameter of several tens to several hundreds nm on the electrode surface by a thermal CVD method.

[0003]

However, the above Sn
The O2 electrode is expensive because of its special manufacturing method compared to a general ITO electrode film, and has problems such as a high reaction temperature. In order to obtain a more effective texture structure, it is necessary to increase the film thickness to several hundreds to several thousand nm, and to achieve a film thickness of 70 to 90 nm, which can reduce reflection loss in the wavelength region most necessary for amorphous silicon solar cells. Is very low.

[0004] Therefore, an object of the present invention is to provide an amorphous silicon solar cell that solves the above-mentioned problems.

[0005]

In order to achieve the above-described object, the present invention is characterized in that hemispherical dimples are formed on the surface of a glass substrate to be used, and an electrode film and an amorphous silicon film are laminated thereon. And By forming the dimples ahead, the effective surface area of the solar cell with respect to the substrate area is increased, and the current output is improved. The improvement of the current output in the amorphous silicon solar cell of the present invention does not depend on the structure of the transparent electrode, and thus does not depend on the material, thickness and shape of the transparent electrode formed on the substrate.
For this reason, it is possible to solve the problem ahead and further improve the current output. In a structure in which a transparent electrode film, an amorphous silicon film, and a metal electrode film are stacked in this order and light is incident from the glass substrate side, a metal electrode film, an amorphous silicon film, and a transparent electrode film are stacked in this order, and the transparent electrode film is stacked in that order. It is also effective in a structure in which light is incident. Further, since the surface of the glass substrate has a hemispherical dimple structure, it is effective in strength for a glass substrate having an acute angle of unevenness.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an amorphous silicon solar cell element according to the present invention has a transparent electrode film (02), an amorphous silicon film (03), a glass substrate (01) on which hemispherical dimples are formed. Further, it has a structure in which a metal electrode film (04) is laminated. If necessary, a protective film (0
5) may be formed. In addition, the glass substrate (0
1) A structure in which a metal electrode film (04), an amorphous silicon film (03), a transparent electrode film (02), and, if necessary, a protective film (05) may be laminated thereon in this order.

The formation of a hemispherical dimple shape on a glass substrate can be obtained by roughening the surface by a sand blast method or a water blast method and then treating the surface with a strong acid such as hydrofluoric acid.

[0008]

The present invention will be described below with reference to examples.

A Corning # 7959 having a thickness of 1.1 mm was used as a glass substrate. The glass substrate was roughened by a water blast method in which water mixed with an alumina powder (maximum particle diameter 19 μm) as an abrasive was sprayed. As for the surface state at this stage, relatively sharp unevenness having a height of several tens to several hundreds of nm is observed on the entire surface. Thereafter, the substrate was further treated in a hydrofluoric acid aqueous solution (at room temperature, 25%, 15 seconds) to etch the roughened glass surface, thereby obtaining a hemispherical dimple shape having a smooth curve.

FIG. 2 is a schematic cross-sectional view of the obtained glass substrate having a dimple shape. Diameter (r) 0.5 to 5.0μ
m, depth (d) is in the shape of a hemispherical dimple of 0.1 to 1.0 μm that covers the entire surface, with an average diameter of 2.0 μm and depth
Most dimples of about 0.5 μm are formed.

On the surface having the dimple shape, an ITO (indium tin oxide) film was formed as a transparent electrode film by an 80 nm sputter link method. An amorphous silicon film was laminated thereon by PECVD. This amorphous silicon film has a P layer composed of B-doped a-SiC: H, a-Si
C: H interface layer, a-Si: H I layer, P-doped a
-Layed in order of N layers consisting of Si: H, and the thickness of each layer is
They were 15 nm, 20 nm, 500 nm, and 40 nm. Further, an Al film was formed at 90 nM as a metal electrode to obtain an amorphous silicon solar cell. A hemispherical dimple shape similar to the surface shape of the glass substrate is formed on the surface of the obtained amorphous silicon solar cell.

The amorphous silicon solar cell (A) thus obtained, the amorphous silicon solar cell (B) similarly formed on an untreated glass substrate having a flat surface, and a glass having a flat surface Amorphous silicon solar cell formed similarly using SnO2 transparent electrode with texture structure instead of ITO transparent electrode on substrate
The current output characteristics of (C) were evaluated. The evaluation was performed under a 500 lx white fluorescent lamp.

As a result, the obtained short-circuit current is: (A): 4
9.5 μA / cm2, (B): 40.1 μA / cm2, and (C): 50.1 μA / cm2. As can be seen from the results, the use of the glass substrate having the dimple shape can improve the current output by about 1.2 times as compared with the case where the flat glass substrate is used. It was equivalent to the case where the SnO2 electrode was used.

Further, the dimple shape is 2 μm in diameter and depth
The surface area was assumed to be 0.5 μm, and the surface area assuming that the dimples were closest packed in the unit area was about 1.2 times the flat surface, which was in good agreement with the evaluation result.

This result shows that the formation of the hemispherical dimple structure on the glass substrate as described above increases the effective surface area, thereby improving the current output.

[0016]

As described above, the amorphous silicon solar cell of the present invention uses a glass substrate having hemispherical dimples formed on the surface, thereby increasing the effective surface area, and consequently, the unit area. This has the effect of improving the current output per unit. Further, since this effect does not depend on the material and shape of the transparent electrode, a transparent electrode of an arbitrary shape and material can be used. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional structure of an amorphous silicon solar cell

FIG. 2 is a cross-sectional view of a glass substrate.

[Explanation of symbols]

 01 Glass substrate 02 Transparent electrode film 03 Amorphous silicon film 04 Metal electrode film 05 Protective film r Diameter of dimple d Depth of dimple

Claims (3)

[Claims] 1. An amorphous silicon solar cell comprising a glass substrate, a transparent conductive film, an amorphous silicon film, and a metal electrode film, wherein a glass substrate having a hemispherical dimple shape on its surface is used. An amorphous silicon solar cell formed thereon. 2. An amorphous silicon solar cell comprising a glass substrate, a transparent conductive film, an amorphous silicon film, and a metal electrode film, wherein a glass substrate having a hemispherical dimple shape on its surface is used. An amorphous silicon solar cell, wherein the surface of the amorphous silicon solar cell formed thereon has a hemispherical dimple shape. 3. An amorphous silicon solar cell comprising a glass substrate, a transparent conductive film, an amorphous silicon film, and a metal electrode film, wherein a glass substrate having a hemispherical dimple shape on its surface is used. The method of manufacturing an amorphous silicon solar cell formed thereon, comprising forming the hemispherical dimple shape by roughening the surface of a glass substrate by a blast method, and then etching the surface with a hydrofluoric acid aqueous solution. Solar cell manufacturing method