Strategies toward efficient tin-based perovskite solar cells

Tin halide perovskite solar cells are considered one of the most promising alternatives to conventional lead-based perovskite photovoltaics due to their structural and electronic similarities, along with their lower toxicity. However, the chemistry of tin halide perovskites is distinct from that of their lead counterparts. As a result, tin halide perovskite solar cells still lag behind lead-based devices in both performance and long-term stability. This review summarizes recent progress in strategies to address these challenges, focusing on controlling key issues such as Sn²⁺ oxidation, rapid crystallization, and high defect densities. Specific approaches discussed include precursor purification, the use of chemical additives, compositional engineering, surface modifications, interlayers, and the design of charge-transporting materials. Future advances will require the development of thicker high-quality absorber layers, robust electron- and hole-selective contacts, improved operational durability, and scalable fabrication methods. These integrated strategies will be essential for realizing efficient, stable, and large-area lead-free perovskite photovoltaics.