Fabrication of solar cells using Ge–Sn–S thin film prepared by co-evaporation

Abstract

Abstract In this study, we produced thin-film solar cells using co-evaporated Ge–Sn–S thin film as the light-absorbing layer. The thin films were prepared at different concentrations of Ge and substrate temperatures. We characterized the solar cells and compared their physical properties with those of an SnS thin film fabricated using only Sn and S. The Ge x Sn1−x S (x = 0.27) thin film solar cell exhibited the best performance, with short circuit current density J sc = 0.66 mA cm−2, curve factor FF = 0.324, power conversion efficiency PCE = 0.036%, and open circuit voltage V oc = 0.169 V. The band gap of the Ge x Sn1−x S (x = 0.27) thin film estimated by extrapolating the absorption edge of the external quantum efficiency was 1.57 eV, which is larger than that of the SnS thin film. This suggests that Sn (in SnS) is partially replaced by Ge to form a solid solution, thus widening the band gap.