Pure Tin Halide Perovskite Solar Cells: Focusing on Preparation and Strategies

Metal halide perovskite solar cells (PSCs) have emerged as an important direction for photovoltaic research. Although the power conversion efficiency (PCE) of lead‐based PSCs has reached 25.7%, still the toxicity of Pb remains one main obstacle for commercial adoption. Thus, to address this issue, Pb‐free perovskites have been proposed. Among them, tin‐based perovskites have emerged as promising candidates. Unfortunately, the fast oxidation of Sn2+ to Sn4+ leads to low stability and efficiency. Many strategies have been implemented to address these challenges in Sn‐based PSCs. This work introduces stability and efficiency improvement strategies for pure Sn‐based PSCs by optimization of the crystal structure, processing and interfaces as well as, implementation of low‐dimension structures. Finally, new perspectives for further developing Sn‐based PSCs are provided. The review discusses the stability of crystal structure, summarizes the factors affecting crystal stability, and analyzes the physical properties of crystals. Then, the preparation of tin‐based perovskite devices is summarized and discussed in detail with respect to four aspects: thin film manufacturing processes, additive selection, preparation of low‐dimensional structures and selection of interface layers.