Enhancing the Stability of Air‐Processed Flexible Perovskite Solar Cells via Self‐Healing Fluorinated Polyurethane‐Induced Lattice Reconstruction

ABSTRACT Flexible perovskite solar cells (f‐PSCs) have attracted considerable attention for portable and wearable electronics. However, grain‐boundary cracking and defect accumulation cause irreversible efficiency loss and device failure. Here, a self‐healing fluorinated polyurethane (S‐FPU) containing dynamic disulfide bonds and fluorinated soft segments is incorporated into MAPbI 3 perovskites to simultaneously improve the power conversion efficiency and mechanical durability of f‐PSCs. The S‐FPU coordinates with undercoordinated Pb 2+ sites exposed by fracture‐induced lattice distortion under cyclic loading, stabilizes the iodide coordination environment, and homogenizes surface potential, thereby effectively suppressing deep‐level trap states. Thermal activation triggers reversible disulfide exchange within S‐FPU, enabling rapid crack closure, strain relaxation, and coupled mechano‐electronic self‐healing. Consequently, the flexible devices deliver a power conversion efficiency of 21.13% while retaining over 80% of their initial efficiency after 1000 h under ISOS‐D‐3 conditions. Notably, the devices maintain more than 95% of their initial efficiency after 1000 bending cycles with a bending radius of 2 mm and 80% after 4000 cycles. After 6000 bending cycles, a brief thermal stimulus (80°C) followed by room‐temperature storage restores efficiency to near its initial value, demonstrating reliable multi‐cycle self‐healing capability.