Interfacial Modulation of Perovskite Solar Cells: Defect Suppression, Ion Migration, and Mechanical Stability

Interfaces play a central role in perovskite solar cells (PSCs), governing charge extraction, recombination dynamics, and operational stability. Precise interfacial engineering is therefore essential for enabling efficient carrier transport, suppressing nonradiative recombination, and prolonging device lifetime. Nevertheless, persistent interfacial challenges, including defect accumulation, energy‐level mismatch, ion migration, and thermomechanical degradation arising from thermal expansion mismatch, remain major barriers to further improvements in both efficiency and durability. This review systematically summarizes recent advances in interfacial engineering for PSCs, with particular emphasis on the underlying physicochemical principles. Progress in the engineering of top interfaces, buried interfaces, and vertically integrated dual‐interface strategies is comprehensively discussed. Finally, future opportunities and challenges for realizing highly efficient and robust PSCs under large area fabrication and harsh operating conditions are highlighted.