摘要：SummaryPerovskite solar cells (PSCs) have achieved extremely high power conversion efficiencies (PCEs) of over 25%, but practical application still requires further improvement in the long-term stability of the device. Herein, we present anin situinterfacial contact passivation strategy to reduce the interfacial defects and extraction losses between the hole transporting layer and perovskite. The existence of PbS promotes the crystallization of perovskite, passivates the interface and grain boundary defects, and reduces the nonradiation recombination, thereby leading to a champion PCE of 21.07% with reduced hysteresis, which is one of the best results for the methylammonium (MA)-free, cesium formamidinium double-cation lead-based PSCs. Moreover, the unencapsulated device retains more than 93% and 82% of its original efficiencies after 1 year's storage under ambient conditions and thermal aging at 85°C for 1,000 h in a nitrogen atmosphere, likely due to the usage of MA-free perovskite and the enhanced surface hydrophobicity.Graphical AbstractDisplay OmittedHighlights•Anin situinterfacial defects contact passivation strategy has been developed•PbS quantum dots were used as the passivant to reduce the traps of perovskite films•The methylammonium-free device with passivation layer gives efficiency over 21%•The unsealed device demonstrated excellent ambient and thermal long-term stabilityElectrochemical Energy Storage; Energy Materials; Devices; Materials Structure
