Strain in Halide Perovskite Solar Cells: Origins, Impacts, and Regulation

Perovskite solar cells have made significant progress in the past decade, demonstrating promising potential for next‐generation solar technology. However, the strain‐induced intrinsic instability of mixed‐halide perovskites poses a significant obstacle to their widespread commercialization. Relaxation of the perovskite lattice strain is a crucial approach for enhancing photovoltaic performance and broadening their application potential. In this study, the authors conduct an analysis of strain progression in perovskite thin films, examining its impact on the physical properties of perovskites and the performance of perovskite solar cells. Furthermore, they explore its influence on device stability from the perspectives of phase transitions, chemical decomposition, and mechanical fragility. Additionally, they provide a summary of key advancements in strain‐relaxation strategies and offer design principles and synthetic approaches to address the issue of lattice strain in perovskites. This paper is intended to lay the groundwork for the theoretical development of effective strain‐relaxation methods, moving beyond sole reliance on empirical optimization.