Improving stability and efficiency of perovskite solar cells via a cerotic acid interfacial layer

Organic-inorganic hybrid perovskite solar cells (PSCs) are one of the most promising technologies in the field of photovoltaics due to its high-power conversion efficiency (PCE) and easy fabrication process. However, its moisture stability has posed a crucial hurdle towards its further commercialization. In this paper, we have introduced an interfacial layer, cerotic acid (CA), inspired from the honeycomb, to modify the surface of perovskite films, thus improving moisture stability. The PCE of the CA modified PSCs retained ~81% of its initial value after aging 30 days at a relative humidity of 35%, in sharp contrast with the pristine devices, only 19% retention of its initial value. In addition, the C=O group in CA was found effectively passivate the unsaturated Pb sites in perovskite films and further contributes to the PCE of devices. Overall, this work has demonstrated a simple, potentially low-cost, and environmentally friendly method to improve not only the photovoltaic performance but also the moisture stability.