Highly efficient perovskite solar cells fabricated under a 70% relative humidity atmosphere

Abstract Considering the practical manufacture process, developing new technologies for the fabrication of perovskite solar cells (PSCs) under an ambient atmosphere is highly desired. In this study, high-quality perovskite films are effectively fabricated under a relative humidity of 70% atmosphere through the substrate preheating process assisted by methyl acetate as an antisolvent. The effect of preheating substrate temperature on photovoltaic properties of PSCs is investigated. The PSCs fabricated with the substrate preheating process present high-quality crystalline, low charge transport resistance at interfaces, high charge recombination rate, and low hysteresis. Substrate preheating temperature of 120 °C leads to the highest power conversion efficiency (16.13%) of the conventional planar MAPbI3 PSCs with open-circuit voltage of 1.109 V and short-circuit current of 19.71 mA cm−2, an increase of 75% on efficiency compared to the pristine cell. The enhancement is not attributed to the removal of the absorbed water on the surface of hole transport layers but arises from the prevention of the MAPbI3 films from the ingress of water during the crystallization process under a high humidity atmosphere through the evaporation of solvents accelerated by the heated substrates. This work provides a promising way for the fabrication of PSCs under a high humidity atmosphere.