B-site doping with bismuth ion enhances the efficiency and stability of inorganic CsSnI3 perovskite solar cell

B-site doping with bismuth ion (Bi3+) is adopted to enhance the quality and stability of CsSnI3 perovskite. The partial displacement of Sn2+ with Bi3+ can not only improve the morphology, crystallinity, and stability of CsSnI3 perovskite film, but also reduce the trap density of CsSnI3 perovskite. Consequently, the fabricated perovskite solar cell with Bi3+-doped CsSnI3 perovskite deliver a high power conversion efficiency of 6.11 %, which is increased by 77 % compared to the efficiency of the control cell. In addition, the device without any encapsulation preserves over 72 % of its initial efficiency after storage in ambient condition for 240 h.