JPS59213177A - Thin film solar battery - Google Patents

Abstract

PURPOSE:To enable to increase the electromotive current and to improve the conversion efficiency by a method wherein an inclined plane is formed on the surface of light incidence to the region for connection generated necessarily, and the light is made incident to a power generating region by scattering it in the case of series connection by forming a plurality of photo power generating regions on a common substrate. CONSTITUTION:Clear electrode patterns 21-25, amorphous semiconductor layers 31-35, and metallic electrode patterns 41-45 are formed in this order on the glass substrate 1. However, grooves 50-55 of e.g. triangular section are cut at the part of non power generating region on the lower surface of the glass substrate 1. By this manner, in the presence of the incident light 6 shown by the arrow mark in the groove 52 for example, a part 61 of said light becomes refracted at the interface at the groove part and then reaches the power generating region. On the other hand, the reflected light 62 likewise reaches another power generating region.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in thin film solar cells formed on transparent insulating substrates.

[Prior art and its problems]

FIG. 1 shows a cross-sectional structural diagram of a conventional thin-film solar cell of this type connected in series. Transparent electrode patterns 21 to 25 are usually made of ITO (indium tin oxide) on a transparent insulating substrate 1 made of glass or the like. etc. is formed. The amorphous semiconductor layers 31 to 35 stacked thereon are, for example, p-type crystalline silicon (hereinafter referred to as a-Si) from the transparent electrode side.
, a non-doped Me8T layer 5000X, and an n-type A-St layer 500A, each oP type, non-doped, and n-type a-81 layer is made of diborane, silane, silane,
Formed by glow discharge decomposition of gases consisting of phosphine and silane. In this method, the zero-order metal electrode nozzles 741 to 45 and 40 are formed by vapor deposition or the like, which is well known to those skilled in the art. The metal electrode turns 41 to 45 are formed to be electrically connected to the transparent electrode turns 21 to 25, respectively.In such a structure, the semiconductor layer is sandwiched between the transparent electrode and the metal electrode. For example, sunlight incident on the area A in Figure 1 is converted into electricity and becomes a so-called power generation area (effective area), but the connection area B.T.
In other words, the ends C and D become non-power generation regions (ineffective regions).

The area of this non-power generation area can be reduced by improving the manufacturing process, but since there is power loss due to contact resistance at the contact area between metal electrodes and transparent electrodes, it is essential to make it negligibly small. It is technically impossible. Therefore, it has been empirically found that the effective area ratio (ratio of effective area to total area) of a solar box or pond having the structure shown in FIG. 1 is approximately 85% at most.

[Purpose of the invention]

An object of the present invention is to reduce the ineffective portion of incident light to the thin-film solar cell having the structure described above, and to improve power generation efficiency.

[Key points of the invention]

In the present invention, a plurality of photovoltaic regions each having a transparent electrode, a semiconductor thin film, and a metal electrode laminated in a direction perpendicular to the substrate surface are formed on one side of a single transparent insulating substrate, and each region is connected in series. In the present invention, light incident on the other surface of the substrate is scattered by providing an inclined surface on the other surface of the substrate facing the area existing between the regions, and the scattered light is guided to the photovoltaic region, It improves effective efficiency.

[Embodiments of the invention]

FIG. 2 shows a sectional view of a first embodiment according to the invention. The basic structure is the same as the conventional series-connected solar cell shown in FIG. 1, and transparent electrode patterns 21 to 25. Amorphous semiconductor layers 31 to 35. Metal electrode patterns 41 to 45 are formed in this order. However, as shown in the figure, grooves 50 to 55 having a triangular cross section are cut in the non-power generation area on the lower surface of the glass substrate. By doing this, for example, when there is incident light 6 shown by the arrow in the groove 52, a part of the incident light 61 is refracted at the interface of the groove portion and reaches the power generation region. On the other hand, the reflected light 62 similarly reaches another power generation area. In an experiment, a groove was made using a diamond grinder on a solar cell in which the width of the power generating area A was 7.7 ygm, the width of the ineffective area B was 20 ygm, and the thickness of the glass plate 1 was 1.1 ygm. Compared to the conventional type, it has increased by 6qb.

According to simple calculations, this is approximately 1/4 of the light incident on the ineffective area.
is now alive.

FIG. 3 is a sectional view of a second embodiment according to the invention. The basic configuration is the same as the conventional type, but rough surfaces 70 to 75 with glass-like unevenness are provided in the non-power generation area of the surface of the glass substrate as shown in the figure. The incident light is scattered and a portion reaches the power generation area. Actually, the width of the power generation area is 7.7 mm, and the width of the ineffective area is 2.
．． Omm, when an experiment was carried out by forming ground glass surfaces 70 to 75 by sandblasting on a solar cell in which the thickness of the glass plate 1 was 11 mm, the current increased by about 4 inches. Although we have shown that a rough surface is created by making grooves on the bottom surface of the substrate with a grinder or by sandblasting, it is also possible to form sloped surfaces of any size on the surface of the substrate using other methods to scatter incident light. Good 0 [Effect of the Invention] The present invention forms a plurality of photovoltaic regions on a common substrate, and in order not to invalidate all the light incident on the connection region that inevitably occurs when connecting them in series, Grooves on the light incident surface,
Alternatively, a sloped surface such as a rough surface is formed and the light incident on the slope is scattered and incident on the power generation area to contribute to photovoltaic power generation. This increases the electromotive current of the solar cell and converts it. The effect is extremely large because efficiency can be improved.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional series-connected thin film solar cell;
The figure is a cross-sectional view of one embodiment of the present invention, and FIG. 3 is a cross-sectional view of another embodiment. 1 Transparent insulating substrate, 21-25 Transparent electrode, 31-35
... Amorphous semiconductor layer, 40-45 Metal electrode, 50-
55...Groove, 70-75...Rough surface.

Claims (1)

[Claims] 1) A plurality of photovoltaic regions each having a transparent electrode, a semiconductor thin film, and a metal electrode laminated in a direction perpendicular to the substrate surface are formed on one side of one transparent insulating substrate, and each region is Thin film solar cell 02, which is connected in series and is characterized in that an inclined surface is formed on the other surface of the substrate facing the area between the regions, the cell according to claim 1. A thin film solar cell characterized in that the inclined surface is formed as a groove on the surface of the substrate. 3) A thin film solar cell according to claim 1, characterized in that the inclined surface is formed as a rough surface.