Advancing Efficiency and Stability of Lead, Tin, and Lead/Tin Perovskite Solar Cells: Strategies and Perspectives

Halide-perovskite-based solar cells (HPSCs) have established themselves as a promising photovoltaic (PV) technology in a remarkably short time. The rapid improvement in HPSCs can be attributed to the unique material and optoelectronic properties of metal halide perovskite semiconductors coupled with a very knowledgeable and experienced PV community. This review briefly summarizes the chemistry of halide perovskites, delving into the fundamental aspects of crystal structure and optical bandgap, followed by a more in-depth report on the advancements in HPSCs efficiencies, thanks to structural regulation, interfacial modulation, and thin-film engineering. It is mainly focused on three metal halide perovskites topics: 1) high-performance Pb-based perovskites, 2) Sn-based perovskites and their associated challenges, and 3) emerging work on mixed composition Pb–Sn perovskites. For each of these domains, the effects stemming from the tuning of the monovalent A-site and the halide site are examined. Additionally, various approaches aimed at passivating defects in the bulk film and at the interface, along with carrier transport engineering, are discussed. The discussions also encompass the broader implications for device performance, stability, and material toxicity. Finally, perspectives on the future directions and the commercial feasibility of perovskite photovoltaic technologies are provided.