Enhanced-Efficiency Flexible Perovskite Solar Cells with Surface Reconstruction and Defect Passivation Induced via High-Temperature Post-Treatment

Flexible perovskite solar cells (<i>f</i>-PSCs) have attracted much attention due to their potential to power mobile or wearable electronic products with sustainable energy. However, challenges persist in achieving dense, few-defect, and high-quality perovskite crystal films, which are essential for enhancing the efficiency and stability of <i>f</i>-PSCs. In this study, we develop a technique of surface reconstruction and defect passivation involving interface modification through high-temperature annealing of 4-trifluorophenylmethylammonium iodide (CF₃PMAI) to produce a dense perovskite film with large grains, few defects, and superior crystal quality. This approach leverages the dual functions of high-temperature annealing (140 °C instead of the normal temperature of 100 °C) and interface layer CF₃PMAI on perovskite recrystallization, along with the impact of CF₃PMAI defect passivation on the perovskite film. As a result, our champion rigid and flexible PSCs utilizing CF₃PMAI high-temperature annealing achieve remarkable power conversion efficiencies (PCEs) of 24.74% and 23.82%, respectively. Furthermore, PSC devices exhibit significantly enhanced light stability compared to those treated with a conventional annealing process.