8.1% efficient Cu2Zn(Sn,Ge)(S,Se)4 solar cell based on a single-target sputtering method

Abstract In this paper, we prepared Cu 2 Zn(Sn,Ge)(S,Se) 4 (CZTGSSe) films based on a single-target sputtering method. This method involves the sputtering of precursor film from a compound target and a following selenization process with Se and GeSe 2 . The properties of the CZTGSSe film was compared with the CZTSSe film which was prepared using the same process but without using GeSe 2 during the selenization. We find the usage of GeSe 2 can incorporate Ge element into the selenized films and modify its composition. The crystallization process in the films is influenced and a uniform morphology can be achieved by using GeSe 2 . The GeSe 2 may also influence the defect formation and electrical properties of the selenized films. By using GeSe 2 during the selenization process, the efficiency of the solar cell can be improved from 4.2% for CZTSSe to 8.1% for CZTGSSe.