Room Temperature Processing of Inorganic Perovskite Films to Enable Flexible Solar Cells

Inorganic lead halide perovskite materials have attracted great attention recently due to their potential for greater thermal stability compared with hybrid organic perovskites. However, the high processing temperature to convert from the non-perovskite phase to the cubic perovskite phase in many of these systems has limited their application in flexible optoelectronic devices. Here, we report a room temperature processed inorganic perovskite solar cell (PSC) based on CsPbI₂Br as the light harvesting layer. By combining this composition with key precursor solvents, we show that inorganic perovskite films can be prepared by the vacuum-assist method under room temperature conditions in air. Unencapsulated devices achieved power conversion efficiency up to 8.67% when measured under 1-sun irradiation. Exploiting this room temperature process, flexible inorganic PSCs based on an inorganic metal halide perovskite material are demonstrated.