Fully hot Air-Processed All-Inorganic CsPbI2Br perovskite solar cells for outdoor and indoor applications

The all-inorganic alpha-CsPbI2Br perovskite has emerged as a promising material for photovoltaic applications due to its superior optoelectronic properties and thermal stability. However, achieving a defect-free, crystalline CsPbI2Br perovskite film remains challenging due to the rapid crystal growth induced via high-temperature hot plate processing, which causes surface defects including pinholes and voids. This study introduces a novel hot plate-free methodology in which the perovskite film is fully processed using a dynamic hot air treatment under ambient conditions. Crystallographic and microscopic analyses reveal that hot air-assisted method produces highly crystalline, uniform, and compact perovskite film. The controlled crystal growth mechanism facilitated by the hot air process involves the formation of an intermediate phase (CsI-DMSO:PbX2), followed by gradual solvent evaporation, resulting in improved film quality. The resulting perovskite solar cells (PSCs) exhibited a champion power conversion efficiency (PCE) of 13.74 % and maintained around 51.60 % of its initial PCE after thermal aging at 85 degrees C under ambient conditions over 1440 h. Furthermore, under indoor white LED illumination (3200 K, 1000 lx), the optimized PSC achieved an impressive PCE of 22.50 %. These findings demonstrate that the dynamic hot air process is a viable and scalable technique for producing high-performance, stable PSCs under ambient conditions.