Open-Circuit Voltage Deficits in Tin-Based Perovskite Solar Cells.

The power conversion efficiency of Pb-based single-junction perovskite solar cells (PSCs) has surpassed 26%; however, the biocompatibility concerns associated with Pb pose threats to both the environment and living organisms. Consequently, the development of Pb-free PSCs is imperative. Among the various alternatives to Pb-based PSCs, Sn-based PSCs have exhibited outstanding optoelectronic properties, showing great potential for large-scale manufacturing and commercialization. Nevertheless, there remains a significant efficiency gap between Sn-based and Pb-based PSCs. The disparity primarily stems from substantial open-circuit voltage (VOC) deficits in Sn-based PSCs, typically ranging from 0.4 to 0.6 V. The main reason of VOC deficits is severe non-radiative recombination losses, which are caused by the uncontrolled crystallization kinetics of Sn halide perovskites and the spontaneous oxidation of Sn2+. This review summarizes the reasons for VOC deficits in Sn-based PSCs, and the corresponding strategies to mitigate these issues. Additionally, it outlines the persistent challenges and future prospects for Sn-based PSCs, providing guidance to assist researchers in developing more efficient and stable Sn-based perovskites.