Bridging Oxidation and Crystallization Pathways in Sn–Pb Perovskites for High‐Efficiency, Stable Solar Cells

All‐perovskite tandem solar cells (TSCs) have recently surpassed the 30% power conversion efficiency milestone, positioning mixed tin–lead (Sn–Pb) perovskite as indispensable narrow‐bandgap absorbers. Their optimal bandgap, reduced lead content, and solution processability make them promising for next‐generation photovoltaics. However, their widespread application is hindered by severe stability issues, primarily the facile oxidation of Sn 2+ and crystallization mismatch between Sn‐ and Pb‐based phases. Distinct from existing reviews, this short review provides an integrated framework for the two fundamental bottlenecks of Sn–Pb perovskite—Sn 2+ oxidation and Sn/Pb crystallization mismatch—linking mechanistic insights across precursor chemistry, thin‐film formation, and device operation. We summarize recent advances that enable efficiencies >23% together with thousand‐hour operational stability, and we outline future directions toward fully integrated, scalable, and commercialization‐relevant stability solutions.