Strategies for Improving the Stability of Tin‐Based Perovskite (ASnX3) Solar Cells

: Although lead-based perovskite solar cells (PSCs) are highly efficient, the toxicity of lead (Pb) limits its large-scale commercialization. As such, there is an urgent need to find alternatives. Many studies have examined tin-based PSCs. However, pure tin-based perovskites are easily oxidized in the air or just in glovebox with an ultrasmall amount of oxygen. Such a characteristic makes their performance and stability less ideal compared with those of lead-based perovskites. Herein, how to address the instability of tin-based perovskites is introduced in detail. First, the crystalline structure, optical properties, and sources of instability of tin-based perovskites are summarized. Next, the preparation methods of tin-based perovskite are discussed. Then, various measures for solving the instability problem are explained using four strategies: additive engineering, deoxidizer, partial substitution, and reduced dimensions. Finally, the challenges and prospects are laid out to help researchers develop highly efficient and stable tin-based perovskites in the future.