Morphology control of perovskite film for efficient CsPbIBr2 based inorganic perovskite solar cells

Inorganic perovskite solar cell (PSC) has been emerging as one of the most promising photovoltaic technologies for future application due to its excellent thermal stability and high power conversion efficiency (PCE). However, the efficiency of state-of-the-art CsPbIBr2–based PSCs is not satisfactory due to the poor quality of CsPbIBr2 perovskite film. Herein, by combining both substrate preheat treatment (SPT) and NH4PF6 precursor additive engineering, we prepared the high-quality CsPbIBr2 perovskite film featuring full coverage, high crystallinity and large crystal grain size, resulting in improved light harvest and reduced nonradiative charge recombination. With these morphology optimizaitons, the PSCs demonstrate a champion efficiency of 10.1% under 100 mW cm−2 illumination. Moreover, CsPbIBr2-based PSC without encapsulation exhibits excellent moisture stability by showing negligible drop in PCE under 40% relative humidity for 30 days.