Abstract: The present method provides a method for preparing the PI varnish which has the steps of: 1) preparing a mixed solution of 60-100% by weight aprotic solvent, and 0-40% by weight aromatic solvent; 2) adding into the mixed solution in a mole ratio of 1:9 two aromatic diamines; and 3) further adding in the mixed solution in a mole ratio of 1:5 two aromatic dianhydrides. Such PI has a suitable thermal expansion coefficient and characteristics different form those of the PI currently in use.

Abstract: A method of manufacturing a flexible amorphous silicon solar cell includes the steps of: a) coating a PI varnish on a glass substrate; b) imidizing the PI varnish film; c) vacuum-depositing a metal film on the PI film; d) vacuum-depositing an amorphous silicon film on the metal film; e) vacuum-depositing a transparent conducting film on the amorphous silicon film; and f) separating the PI film from the glass substrate. The method also provides for preparing the PI varnish by the steps of: 1) preparing a mixed solution of 60-100% by weight aprotic solvent, and 0-40% by weight aromatic solvent; 2) adding into the mixed solution in a mole ratio of 1:9 two aromatic diamines; and 3) further adding in the mixed solution in a mole ratio of 1:5 two aromatic dianhydrides.