Debridement Strategy by Pre-Bending Passivation for Flexible All-Inorganic Perovskite Solar Cells Beyond 70 000 Bending Cycles

The mechanical durability and efficiency of all-inorganic flexible perovskite solar cells (f-PSCs) still require enhancement for practical applications. In this study, a creative debridement strategy to improve the mechanical durability and photovoltaic performance of all-inorganic f-PSCs by pre-bending the flexible perovskite film and then depositing the passivation agent 2-mercaptopyridine is proposed. The pre-bending process induced the generation of microcracks in the perovskite film surface, and 2-mercaptopyridine can more effectively penetrate the interior of the film through the microcracks, thereby further passivating deep surface defects. These microcracks and defects can be perfectly repaired by 2-mercaptopyridine. Bidentate coordination sites of S and N in 2-mercaptopyridine show stronger binding energy with surface defects. The debridement strategy effectively enhanced the crystallization of the film surface and markedly inhibited crack propagation during the film's bending process. The optimized device achieves a champion power conversion efficiency (PCE) of 14.74%. The pre-bent and passivated all-inorganic f-PSC shows 104% of its initial PCE after 15 000 bending cycles at a curvature radius of 3 mm. Remarkably, even after undergoing 70 000 bending cycles at a curvature radius of 5 mm, pre-bent, and passivated f-PSC can retain over 93% of its initial PCE, exhibiting excellent mechanical durability. The innovative strategy introduced in this study involves pre-bending the flexible perovskite film before applying the passivation agent, allowing the bidentate-coordinated passivation agent 2-mercaptopyridine to more effectively penetrate into the flexible film. The optimized device achieves a power conversion efficiency of 14.74%. Undergoing 70 000 bending cycles at a curvature radius of 5 mm, f-PSC retains over 93% of its initial efficiency. image