(DE19882366-T)      A solar battery having a semiconductor layer of a chalcopyrite structure as a light absorption layer and a flexible film as a substrate and being prevented from causing breakdown and peel-off of the semiconductor layer of the chalcopyrite structure due to warping of the flexible film during heat treatment.    To realise this, a poly (p-phenylene terephthalamide) film having a coefficient of thermal expansion of 5.0 x 106 deg. C is used as a substrate (1). After the Ti-base reinforcing layer (6) is provided on the whole back surface of this substrate (1), a first electrode layer (2) is provided on the front surface of this substrate (1), and a p-type semiconductor layer (3) of a chalcopyrite structure is formed as a light absorption layer on the surface of the layer (2).    (JP10547917-X)      A solar battery having a semiconductor layer of a chalcopyrite structure as a light absorption layer and a flexible film as a substrate and being prevented from causing breakdown and peel-off of the semiconductor layer of the chalcopyrite structure due to warping of the flexible film during heat treatment.    To realise this, a poly (p-phenylene terephthalamide) film having a coefficient of thermal expansion of 5.0 x 106 deg. C is used as a substrate (1). After the Ti-base reinforcing layer (6) is provided on the whole back surface of this substrate (1), a first electrode layer (2) is provided on the front surface of this substrate (1), and a p-type semiconductor layer (3) of a chalcopyrite structure is formed as a light absorption layer on the surface of the layer (2).    (US6274805-B1)      A solar battery having a semiconductor layer of a chalcopyrite structure as a light absorption layer and a flexible film as a substrate and being prevented from causing breakdown and peel-off of the semiconductor layer of the chalcopyrite structure due to warping of the flexible film during heat treatment.    To realise this, a poly (p-phenylene terephthalamide) film having a coefficient of thermal expansion of 5.0 x 106 deg. C is used as a substrate (1). After the Ti-base reinforcing layer (6) is provided on the whole back surface of this substrate (1), a first electrode layer (2) is provided on the front surface of this substrate (1), and a p-type semiconductor layer (3) of a chalcopyrite structure is formed as a light absorption layer on the surface of the layer (2).