Stability of Tin–Lead Mixed Perovskite Solar Cells: Challenges, Strategies, and Future Prospects

Tin–lead (Sn–Pb) mixed perovskite solar cells (PSCs) have gained significant attention as top cells for tandem photovoltaic technologies owing to their compositionally tunable bandgaps (1.2–1.4 eV) and superior near‐infrared light absorption. Despite these advantages, their practical deployment is hindered by uncontrolled crystallization dynamics and severe defect formation, which accelerate degradation under ambient conditions. This review provides a comprehensive analysis of the fundamental optoelectronic properties and recent advancements in Sn–Pb hybrid perovskites, with a focus on strategies aimed at enhancing their stability. Key approaches discussed include the design of 2D/3D heterostructures, incorporation of redox‐active additives, solvent engineering, and interfacial modification of charge transport materials. Finally, we highlight the remaining challenges and outline prospective research directions to advance the long‐term stability and commercial viability of Sn–Pb mixed PSCs.