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
       

(color online) (a) Raman spectra and (b) enlarged Se atom peaks of CZTGSSe films with different Ge content.