Cu2ZnSnS4 thin-film solar cells by a closed tube sulfurization under saturated sulfur vapor pressure

Abstract CdS/Cu 2 ZnSnS 4 (CZTS) heterojunction thin-film solar cells were fabricated via a closed tube sulfurization under saturated sulfur vapor pressure. A significant improvement in the crystalline quality of the CZTS polycrystalline thin-film was achieved when the Cu–Zn–Sn metallic-alloy thin-film was sulfurized under saturated sulfur vapor pressure of 4.3 atm at 590 °C due to efficient suppression of re-evaporation of Zn and Sn species during the growth process. Accordingly, the open-circuit voltage and short-circuit current density of the CdS/CZTS heterojunction device were enhanced resulting in the improvement of power conversion efficiency by over 1.7 times compared to the best cell fabricated by the conventional processes under unsaturated sulfur vapor pressure of 1.5 atm.