Investigations on copper zinc tin sulfide thin film grown by nebulizer assisted spray pyrolysis technique for solar photovoltaic applications

Abstract

Recent technological developments in the field of renewable energy paves way for the implementation of thin film photovoltaic solar cells based on earth abundant, nontoxic and highly efficient absorber materials. Device performances around 20% were already realised with the conventional cadmium telluride and copper indium gallium diselenide based thin film solar cells. Mass production was limited due to the scarcity, toxicity and recyclability issues of these compounds. Kesterite family of compounds are found to be promising alternatives to be used as absorbers in photovoltaic conversion process. Among different kesterite compounds, copper zinc tin sulphide was found to have the favourable characteristic properties to act as a solar energy absorber. Although they are found to be environment friendly and cheap, achieving higher efficiency using economic fabrication techniques is still a challenge. The maximum reported efficiency of CZTS absorber based thin film solar cell is only 11% which is much less when compared to the maximum achievable theoretical limit of 33% for single junction solar cell. The complexity in the formation of this quaternary compound, its phase stability and the role of defect and parasitic secondary phases are quite unclear and needs exploration to further increase its efficiency. CZTS absorber thin film can be manufactured by various vacuum and non-vacuum based technologies. In this work, an attempt was made to produce phase pure CZTS thin film through improvised nebulizer assisted spray pyrolysis technique by optimising some of the important growth parameters and subsequent device fabrication was also done to test its capability of energy conversion newline