A solar cell includes a metal layer and a chalcopyrite compound semiconductor layer in this order on a polyimide film. A manufacturing method according to the present invention includes the following steps in the order: cast applying a polyimide precursor solution onto a support base containing an alkali metal; imidizing the polyimide precursor by heating to form a stacked body including a polyimide film on the support base; forming a metal layer on the polyimide film of the stacked body; and forming a chalcopyrite compound semiconductor layer on the metal layer.

The present invention provides a CIGS film substantially free from oxidation of a front surface thereof and a CIGS solar cell employing the CIGS film and substantially free from reduction and variation in conversion efficiency. The CIGS film, which is used as a light absorbing layer for the CIGS solar cell, includes: a first region having a Ga/(In+Ga) ratio progressively reduced along its thickness toward a predetermined first thickness position from a back surface of the CIGS film; a second region having a Ga/(In+Ga) ratio progressively increased along its thickness toward a predetermined second thickness position from the first region; and a third region provided on the second region and having a Ga/(In+Ga) ratio progressively reduced along its thickness toward the front surface of the CIGS film.

A device includes a bottom contact layer on a substrate, an absorber layer on the bottom contact layer, a cap layer on the absorber layer, a hole blocker layer on the cap layer, and a top contact layer on the hole blocker layer. The absorber layer includes oxygen-annealed copper, indium, gallium and selenium. The device has a quantum efficiency greater than about 50%, measured at a voltage of about 1 volt and at a wavelength of about 940 nanometers.

A CIS solar cell having flexibility and high conversion efficiency may be produced, using, as a substrate, a polyimide film which is prepared from an aromatic tetracarboxylic acid component comprising 3,3,4,4-biphenyltetracarboxylic dianhydride as the main component and an aromatic diamine component comprising p-phenylenediamine as the main component, and has a maximum dimensional change in the temperature-increasing step of from 25 C. to 500 C. within a range of from +0.6% to +0.9%, excluding +0.6%, based on the dimension at 25 C. before heat treatment.

Disclosed are a flexible solar cell apparatus and a method of fabricating the same. The flexible solar cell apparatus includes a support substrate including an internal region and an outer region surrounding the internal region, a plurality of solar cells on the internal region, and a protective layer on the outer region and the solar cells. A top surface of each solar cell is lower than a top surface of the outer region of the support substrate.

Three dimensional concave hemisphere solar structures are provided. A photovoltaic solar cell substrate has a light receiving surface and a back surface opposite the light receiving surface. The photovoltaic solar cell substrate light receiving surface has a plurality of gas filled concave hemisphere cavities having a depth and a radius of one millimeter or greater. A substantially planar transparent cover seals the plurality of gas filled concave hemisphere cavities.