Cyclic voltammetry studies of copper, tin and zinc electrodeposition in a citrate complex system for CZTS solar cell application

Cu2ZnSnS4 (CZTS) has attracted considerable attention as the next generation thin film solar cell to replace CIGS because of its price and availability. The electrodeposition method is one of the fabrication methods. The reduction behaviors of each Cu, Sn and Zn from the unitary system were examined. Cyclic voltammtry (CV) was performed to analyze the behaviors. Trisodium citrate was used as the complexing agent to reduce the difference in the reduction potentials of each material. The effects of pH on the stability of the complexes were also investigated and pH 4.7 was selected to minimize the concentration of H3Cit and Cit3−. The reduction potential of Cu was lowered from −0.2 V (vs. Ag/AgCl) to −0.5 V. The reduction potential of Sn was lowered from −0.5 V (vs. Ag/AgCl) to −0.7 V. The reduction potential of Zn was changed from −1.2 V (vs. Ag/AgCl) to −0.7 V. The change in reduction potential in a complex system can allow the fabrication of CZTS thin films from a Cu, Sn and Zn mixed single bath using an electrodeposition method.