Cu2ZnSnSe4: synthesis and characterization

Shah, S. IsmatThin film photovoltaic has attracted much attention for its high potential to decrease production cost to develop cost-effective and high performance solar cells. Among all these promising materials, chalcopyrite copper indium gallium selenide Cu(In, Ga)(S, Se)2 have gained the highest reputation for its achieved high power conversion efficiency. Laboratory-scale conversion efficiency up to 20.3% has been recently achieved for a CIGS solar cell deposited on a glass substrate. Therefore, the successful commercialization of CIGS cell technology highly relies on the cost reduction. However, the element Indium in CIGS is not earth abundant and therefore hinders the further decrease in production cost. As a potential substitute, quaternary chalcogenide Cu 2ZnSnSe4 (CZTSe) has received more attention nowadays, as it consists of all earth abundant elements and therefore is more environmentally friendly. So in this research, we focus on the synthesis and characterization of CZTSe. In this research, quaternary Cu2ZnSnSe4 particles, useful for low cost solar cell synthesis, were successfully prepared using sonochemistry assisted solid state synthesis method. The pathways of the reactions during the synthesis as a function of the annealing temperature were studied by X-ray diffraction and energy dispersive X-ray spectroscopy (EDS) with the identification of the intermediate binary phases (Cu-Se, Zn-Se, Sn-Se), ternary phases (Cu-Sn-Se, Cu-Zn-Se) and the eventual formation of the quaternary phase Cu2ZnSnSe4. The obtained particles were characterized by X-ray diffraction (XRD) and UV-Vis optical absorption spectoscopy. The results showed that the annealing temperature of 450°C is optimal for the formation of pure quaternary phase. However, the temperature range within which pure Cu2ZnSnSe4 could be obtained was very narrow and Cu2ZnSnSe4 decomposes to various binary and ternary phases as the temperature is increased above the stability range. UV-Vis absorption spectroscopy illustrated that the particles had high absorption of visible light and had a direct band gap around 1.2 eV. These findings demonstrated a low-cost and environmentally friendly method to synthesize CZTSe particles.University of Delaware, Department of Materials Science and EngineeringM.M.S.E