Precisely tuning Ge substitution for efficient solution-processed Cu2ZnSn(S, Se)4 solar cells
Wang Xinshou, Kou Dongxing †, Zhou Wenhui, Zhou Zhengji, Tian Qingwen, Meng Yuena, Wu Sixin ‡
       

Top view (a)–(f) and cross-section (g)–(l) SEM images of CZTGSSe with different Ge content of 0%, 5%, 10%, 20%, 30%, and 50%. Scale bar: .