Low-Temperature Fabrication of Flexible Perovskite Solar Cells in Ambient Air with Enhanced Stability

Flexible perovskite solar cells (F-PSCs) have gained significant attention for their potential in wearable and portable electronics. However, their commercialization is limited by the need for an inert atmosphere during fabrication and the challenge of achieving an annealing temperature compatible with the thermal stability of flexible substrates. To address these issues, we employed a facile confined-space annealing (CSA) strategy to fabricate high-quality flexible FAPbI3 films in ambient air. This strategy enabled effective crystallization of the flexible films at 100 °C, ensuring that the entire device fabrication process could be conducted in air with annealing temperatures not exceeding 120 °C. Such a process significantly alleviates substrate deformation and film strain induced by high temperatures. By reducing the phase-transition energy barrier, the perovskite films exhibited more uniform and compact crystallization while suppressing decomposition and secondary-phase formation, thereby markedly enhancing the mechanical stability and long-term reliability of the devices. In addition, we replaced the conventional toxic chlorobenzene with the green solvent ethyl acetate as the antisolvent, which facilitated nucleation and yielded smoother, denser films. The resulting FAPbI3 F-PSCs achieve a power conversion efficiency of 17.61%, demonstrate excellent bending stability (maintaining 80% of initial efficiency after 1000 cycles at a 6 mm radius), and exhibit remarkable moisture stability, retaining 90% of initial efficiency after 500 h at 60% relative humidity. This method provides a viable solution for the scalable production of high-performance, stable F-PSCs.