Flexible Organic Solar Cells: From Material Design and Morphology Optimization to Practical Applications

Flexible organic solar cells (F-OSCs), characterized by lightweight, intrinsic flexibility, indoor-light compatibility, and biocompatibility, represent a promising energy solution for next-generation wearable electronics. However, the inherent multi-layer architecture of F-OSCs introduces complex mechanical failure mechanisms, necessitating a systematic study on degradation pathways to guide rational device engineering. This review summarizes the main strategies for enhancing the mechanical durability of F-OSCs while maintaining their optoelectronic performance. First, an outline of standardized mechanical testing protocols for active layers and devices is provided. Subsequently, the design principles of key materials are analyzed, with a focus on optimizing molecular aggregation and entanglement in the active layers to achieve fracture-resistant flexible photovoltaics. Afterward, the discussion extends to progress in stretchable interface materials and electrode architectures, which collectively reinforce the device durability under deformation. By highlighting emerging applications, the successful integration of F-OSCs with low-power wearable systems is showcased. Finally, the remaining challenges, future directions, and the necessity of an unified mechanical-electrical optimization strategy from molecular engineering to device architecture are discussed. This comprehensive review aims to accelerate the development of mechanically robust F-OSCs for practical wearable technology.