A two-step approach for electrochemical deposition of Cu–Zn–Sn and Se precursors for CZTSe solar cells

A two-step electrochemical route for fabrication of Cu–Zn–Sn (CZT) and Se precursors' layers for a thin film Cu2ZnSnSe4 (CZTSe) absorber for solar cells is demonstrated. The CZT was electrochemically co-deposited in a citrate solution and after that an appropriate amount of Se was electrodeposited on the top. The CZT+Se were annealed in Ar atmosphere using a slow or fast increase in temperature up to 500 °C. SEM with EDX, XRD and Raman spectroscopy examinations of precursors and of the manufactured CZTSe thin films were carried out. The XRD measurements indicated that the CZT precursor contained η-Cu6.26Sn5, Sn and γ-CuZn5 phases. The electrodeposited Se was polycrystalline with a hexagonal structure. The manufactured CZTSe in all the cases presented Cu2ZnSnSe4 with kesterite or partially disordered kesterite structure; however a purer CZTSe phase was formed using the fast increase in the annealing temperature.

► Cu–Zn–Sn layer was electrochemically co-deposited from a citrate solution. ► An appropriate amount of Se was electrochemically deposited onto the Cu–Zn–Sn layer. ► Cu–Zn–Sn and Se precursors' layers were annealed in Ar atmosphere at 500 °C. ► An XRD and Raman spectroscopy examinations proved that pure Cu2ZnSnSe4 phase was formed.