Substrate for solar cell and method for producing the same; substrate treatment apparatus; and thin film solar cell and method for producing the same

A method for producing a solar cell, comprising the steps of:

• spraying abrasive grains onto a first surface of a substrate, the substrate having the first surface and a second surface, where the second surface of the substrate is substantially parallel to the first surface, thereby forming a minute unevenness on the first surface;
• and
• forming a transparent conductive film above the first surface of the substrate, the transparent conductive film having a minute unevenness attributable to the unevenness of the first surface,
• wherein an injection pressure for spraying the abrasive grains is around 2 to 10 kg/cm.sup.2 and an injection distance is around 40 to 300 mm, wherein the unevenness on the first surface of the substrate has a difference in height between convex portions and concave portions of around 0.1 to 0.5 .mu.m and the height of the unevenness of the transparent conductive film is in approximately the same range as the unevenness of the first surface of the substrate.

A thin film solar cell, comprising:

• a substrate having a first surface;
• a transparent conductive film having a second surface, formed on the first surface of the substrate;
• and
• a semiconductor photoelectric structure for conducting photoelectric transfer, provided on the transparent conductive film so as to be in contact with the second surface of the transparent conductive film,
• wherein the first surface and the second surface each have a minute unevenness whose difference in height between convex portions and concave portions is around 0.1 to 0.5 .mu.m, and wherein the unevenness in the second surface is attributable to the unevenness in the first surface and the height of the unevenness of the transparent conductive film is in approximately the same range as the unevenness of the first surface of the substrate.

A thin film solar cell, comprising:

• a substrate having a first surface;
• a reflecting electrode formed on the first surface of the substrate;
• a semiconductor photoelectric structure for conducting photoelectric transfer, provided on the reflecting electrode;
• and
• a transparent electrode formed on the semiconductor photoelectric structure,
• wherein the first surface of the substrate and the surfaces of the reflecting electrode and the semiconductor photoelectric structure each have a minute unevenness whose difference in height between convex portions and concave portions is around 0.1 to 0.5 .mu.m, and wherein the unevenness in both the reflecting electrode and the semiconductor photoelectric structure are attributable to the unevenness in the first surface of the substrate and the height of the unevenness of the transparent conductive film is in approximately the same range as the unevenness of the first surface of the substrate.

A method for producing a thin film solar cell, comprising the steps of:

• continuously treating a flexible substrate by sandblasting to form a minute unevenness on a surface of the flexible substrate, thereby forming a substrate provided with a first surface having unevenness whose difference in height between convex portions and concave portions is around 0.1 to 0.5 .mu.m;
• forming a metal layer on the first surface of the substrate in such a manner that the unevenness of the first surface of the substrate is reflected on a surface of the metal layer, thereby forming a reflecting electrode;
• forming a plurality of semiconductor layers on the reflecting electrode in such a manner that the unevenness of the surface of the reflecting electrode is reflected on surfaces of the semiconductor layers, thereby forming a semiconductor photoelectric structure for conducting photoelectric transfer;
• and
• forming a transparent conductive film on the semiconductor photoelectric structure in such a manner that the unevenness of the surfaces of semiconductor layers of the semiconductor photoelectric structure is reflected on a surface of the transparent conductive film, thereby forming a transparent electrode,
• wherein the surfaces of the metal layer, the plurality of the semiconductor layers and the transparent conductive film have a minute unevenness whose difference in height between convex portions and concave portions is around 0.1 to 0.5 .mu.m and is attributable to the unevenness in the first surface of the first substrate.