A Thermally Induced Perovskite Crystal Control Strategy for Efficient and Photostable Widea??Bandgap Perovskite Solar Cells

摘要： Wide-bandgap perovskite solar cells (WBG PSCs) have gained attention as promising tandem partners for silicon solar cells due to their complementary absorption, superb open-circuit voltage, and easy solution process. Recently, both their performance and stability have been improved by compositional-engineering or defect-passivation strategies, due to modulation of perovskite crystal size and reduction of crystal defects. In this work, we report a thermally induced phase control (TIPC) strategy, which enables efficient and photostable WBG PSCs without any compositional engineering by exploring a thermal annealing process window of WBG perovskite films for the annealing temperature and time range of 100-175°C and 3-60 minutes, respectively. Within this window, we found a key annealing regime that produces preferred crystal orientations of lead iodide and the WBG perovskite, suppressing phase segregation and reducing charge recombination in the perovskites. The WBG PSC (composition of FA0.75MA0.15Cs0.1PbI2Br and Eg of 1.73 eV) optimized by TIPC exhibited an excellent power conversion efficiency (PCE) of 18.60% and improved operational stability, maintaining >90% of the maximum PCE (during maximum power point tracking) without encapsulation after 12-hour operation under AM 1.5G irradiation in ambient air conditions and after 500-hour operation under white LED irradiation (100 mW cm-2) in inert N2 gas conditions.