Mechanical Stability of Flexible Perovskite Solar Cells: Research Progress, Characterization, Challenges, and Future Perspectives

Driven by global "dual carbon" goals, the transition toward clean and low-carbon energy is irreversible, with solar energy emerging as a core pillar of sustainable energy systems. Flexible perovskite solar cells (FPSCs) have emerged as a photovoltaic research frontier due to their lightweight nature, excellent flexibility, foldability, structural designability, and diverse applications. The power conversion efficiency (PCE) exceeds 26%, approaching that of crystalline silicon cells and demonstrating great commercial potential. However, insufficient mechanical stability remains the most critical and fundamental bottleneck for large-scale practical applications: repeated bending, stretching, and other dynamic mechanical stimuli easily cause perovskite active layer cracking, interfacial delamination, malfunction of the flexible charge transport layer, and electrode degradation, leading to irreversible performance decay. Although researchers have explored multiple strategies to enhance mechanical stability, most reports remain phenomenological, lack systematic comparison, and rarely address scalability or inherent limitations. This review comprehensively summarizes the research progress on FPSCs' mechanical stability, focusing on the intrinsic failure mechanisms, state-of-the-art optimization strategies, quantitative characterization methodologies, standardized evaluation systems, and large-area module performance. Moreover, this work discusses current challenges and future directions, aiming to provide theoretical and technical references for accelerating FPSCs' commercialization.