▎ 摘　　要

NOVELTY - A back contact structure comprises a p-type semiconductor light absorption layer, and a p-type titanium oxide film as a p-type transition layer arranged on the surface of the light absorption layer. USE - The back contact structure is useful for thin film solar cell, which is cadmium telluride thin film solar cell, copper indium gallium selenide thin film solar cell, copper zinc selenium sulfide thin film solar cell, perovskite thin film solar cell and organic thin film solar cell (all claimed). ADVANTAGE - The back contact structure effectively increases the charge transport of hole, reduces interface recombination of photo-generated carrier of holes, improves the absorption of the carrier, and the photoelectric conversion efficiency of the solar cell, has high reliability and current, and provides thin film solar cell, which has high efficiency, and low cost. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a thin film solar cell, which comprises the back contact structure, and a back electrode layer designed on the surface of the titanium oxide film; and (2) preparation of the back contact structure.