Moisture control enables high-performance sprayed perovskite solar cells under ambient conditions

Morphology and crystallization control are critical for metal halide perovskite films in enabling high-performance photovoltaic devices. However, they remain particularly challenging for sprayed devices due to the inherent flaw of the spraying technology—the “coffee-ring” effect (CRE). Herein, we report a moisture-assisted strategy that effectively eliminates CRE and enhances film crystallization through the combined utilization of humidity control and water additives. This approach leads to the formation of Cs0.19FA0.81PbI2.5Br0.5 perovskite films with homogeneous morphology and excellent crystallization, and the power conversion efficiency (PCE) of the champion perovskite solar cells increases from 18.25% to 19.74%. Moreover, unencapsulated devices exhibit excellent stability, with 80% of their initial efficiency retained after operating at 50 °C for over 800 h. Furthermore, the large-area perovskite film (10 × 10 cm2) exhibits significant uniformity throughout the entire film, and the corresponding devices exhibit high consistency and reproducibility. The small-area devices utilizing the same large-area perovskite film show an average PCE of 19.53 ± 0.25%, while mini-modules with an active area of 64.8 cm2 yield an optimal PCE of 16.75%, with an average PCE of 16.08 ± 0.32%.