A simple chemical approach for the deposition of Cu2 ZnSnS4 thin films

The direct synthesis of Cu2ZnSnS4 (CZTS) on substrates by wet-chemistry methods is of great interest for the fabrication photovoltaic thin-film solar cells. We report a simple chemical bath deposition approach to form CZTS thin films on SLG glass substrates. CZTS films were directly deposited onto glass substrate at 60 °C using copper sulfate, zinc sulfate heptahydrate, tin sulfate dihydrate, and sodium thiosulfate as precipitating agents. Deposition of individual metal sulfide (Cu2S, ZnS, and SnS2) showed homogeneous-reaction dominant nanostructures rather than continuous thin film. By contrast, the combination of two or three metal precursors formed continuous thin films. As-grown CZTS films deposited with both NH3 and TEA showed a kesterite CZTS crystal structure. However, the absence of either NH3 or TEA caused no crystallized CZTS film formation. The as-grown CZTS films showed a kesterite crystal structure. Optical absorption study indicated that the as-grown CZTS films had the optimum bang gap energy of 1.6 eV.