Carbonyl‐Amine Synergistic Dual‐Site Passivation for Efficient and Stable Wide‐Bandgap Perovskite Solar Cells

ABSTRACT As the front absorber in all‐perovskite tandem solar cells (TSCs), wide‐bandgap (WBG) perovskite solar cells (PSCs) play a pivotal role in dictating the overall device efficiency. However, a high density of under‐coordinated Pb 2+ at the perovskite surface and a significant mismatch in the interface energy levels can lead to substantial open circuit voltage loss ( V OC ), which can severely affect device stability and pose a significant challenge to the application of WBG PSCs. To address these issues, we treated the perovskite surface with the bifunctional passivating molecule 2‐aminoacetophenone hydrochloride (AAPCl). Mechanistically, the C═O moiety can coordinate with uncoordinated Pb 2+ defects to suppresses interface non‐radiative charge recombination, whereas the ─NH 2 functional group interacts with halide ions to mitigates photoinduced halide segregation. The optimal device we prepared achieved an impressive V OC of 1.348 V and a high power conversion efficiency (PCE) of 20.81%, one of the highest efficiencies reported for 1.78 eV WBG PSCs. Furthermore, the unencapsulated device retained 90% of its initial PCE after ageing in air for 94 days. Consequently, these findings underscore the efficacy of the bifunctional passivation strategy in simultaneously boosting the photovoltaic performance and operational stability of WBG PSCs.