A‐Site Cation Engineering of Metal Halide Perovskites: Version 3.0 of Efficient Tin‐Based Lead‐Free Perovskite Solar Cells

Abstract

AbstractPb‐based metal halide perovskites (MHPs) have emerged as efficient light absorbers in third‐generation photovoltaic devices, and the latest certified power conversion efficiency (PCE) of Pb‐based perovskite solar cells (PSCs) has reached 25.2%. Despite great progress, Pb‐based MHPs are affected by toxicity, which hinders their market entry in a potential future large‐scale commercialization effort. Therefore, the exploration of Pb‐free MHPs has become one of the alternative solutions sought in the community. Among all the Pb‐free MHPs, Sn‐based MHPs show great promise owing to their similar or even superior theoretical optoelectronic characteristics. After several years of development, the PCE of Sn‐based PSCs has recently been approaching 10%, with the breakthroughs mainly coming from A‐site cation engineering of Sn‐based MHPs. In this review, the crucial status of A‐site cation engineering strategies in the research of Sn‐based PSCs is highlighted. First, the way the features of A‐site cation influence the structure and characteristics of MHPs is systematically demonstrated. Then, the state‐of‐the‐art developments, focusing on A‐site cation engineering of Sn‐based MHPs, are comprehensively reviewed. Subsequently, the current challenges and opportunities for further boosting the performance of Sn‐based PSCs are discussed. Finally, conclusions and perspectives on the promising Sn‐based optoelectronic devices are discussed.