Synthesis of chalcogenide photovoltaic semiconductor nanocrystals via mechanochemical reaction

Abstract

Chalcogenide materials are inorganic compound semiconductors that have received unceasing research attentions in energy conversion applications. Especially, CuInGaS2 (CIGS), CdTe, Cu2ZnSnS4 (CZTS) materials are recognized as the representative chalcogenide materials applicable to thin film solar cells. For several decades, various preparation methods of these materials and optimization of their characteristics have been researched by many researchers. In this dissertation, an eco-friendly and facile methods for the synthesis of various chalcogenide nanocrystals applicable to photo energy conversion (PEC) were suggested. The optimized process that excites and applies the mechanochemical reaction and experimental procedures were introduced. From the mechanochemical process, multi-component chalcogenide materials with complex chemical stoichiometries were synthesized with ease. For the fabrication of thin film solar cell devices using CZTS nanocrystals, technique for the preparation of CZTS nanocrystals colloid solution, which would be used for fabrication of CZTS light absorption layer, was developed. CZTS thin film solar cell prepared from inexpensive and non-vacuum processes exhibited PEC of 8 %. The techniques for the facile fabrication of chalcogenide inorganic compound semiconductor nanocrystals and the fabrication of PEC devices using the crystals were developed.Based on these techniques, the development of advanced photovoltaic semiconductor materials was attempted via combining the first principle calculations. CuSb1-xBixS2 material composed of group II–V–V of the periodic table was synthesized and the changes in thermodynamic, crystallographic, and optical properties according to the Sb/Bi ratio were investigated and their causes and results were identified. From this study results, it was ascertained that CuSb1-xBixS2 materials composed of earth-abundant elements hold great promise as a sustainable photo energy conversion material.