Hydrothermal Deposition of UV‐Absorbing Passivation Layers for Efficient and Stable Perovskite Solar Cells

Despite recent increases in perovskite solar cell (PSC) efficiencies, long‐term stability remains a barrier to manufacturing and marketing. SnO2 electron transport layers enable the low‐temperature processing of planer n–i–p structured PSCs. However, ultraviolet radiation damages to the interface between the electron transport layer and the perovskite (PVK), which is a significant issue for n–i–p configuration. Herein, the insertion of a thin CeO2 passivation layer between the SnO2 and PVK is investigated to block the interface degradation. This CeO2 layer improves charge extraction and reduces defects in the PVK/CeO2 interface, resulting in 22.71% power conversion efficiency (PCE) compared to the pristine SnO2 PSC devices, which has a PCE of 20.7%. In addition, after 1700 h of storage at room temperature and 5%–8% RH (dry box), the PCE stability of the reinforced SnO2–CeO2 PSC devices drops from 22% to 19%, whereas that of the pristine SnO2 PSC devices drops from 20% to 16%.