Recent progress in inorganic tin perovskite solar cells

Perovskite solar cell is a bright star in the field of photovoltaic technology. Recently, tin-based perovskites have attracted increasing attention to solve the toxicity faced by those lead halide perovskite compounds. Especially, an extensive investigation on inorganic tin perovskites with essential thermal stability and tunable optical bandgap has been initialized, and progress have been observed in photovoltaics based on them. At present, the maximum power conversion efficiency of solar cells using inorganic tin-based perovskite layer as light absorber has exceeded 10%. We notice Sn²⁺ oxidation is an unavoidable and critical issue for this type of device, representing unstable performing inferior to their lead-based counterparts. In this review, we mainly focus on the origin of Sn²⁺ oxidation for inorganic tin-based perovskites and the correlated degradation mechanism, as well as techniques to characterize their effect on device performance. We discuss several promising approaches to inhibiting the oxidation of Sn²⁺ and improving the stability of devices. We further outlook the effective solutions for inorganic tin-based perovskites for solar cells application with the purpose of augment photovoltaic performance, including power conversion efficiency and device stability, under working condition.