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. SnO 2 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 CeO 2 passivation layer between the SnO 2 and PVK is investigated to block the interface degradation. This CeO 2 layer improves charge extraction and reduces defects in the PVK/CeO 2 interface, resulting in 22.71% power conversion efficiency (PCE) compared to the pristine SnO 2 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 SnO 2 –CeO 2 PSC devices drops from 22% to 19%, whereas that of the pristine SnO 2 PSC devices drops from 20% to 16%.