Interfacial and Doping Synergistic Effect of Versatile Potassium Acetate toward Efficient CsPbI2Br Perovskite Solar Cells

Thefunctional material-based interface and additive engineeringare considered as valid approaches to enhance the photovoltaic performanceof perovskite solar cells (PSCs). However, most of these materialshave been reported to play only one role in PSCs. Herein, we appliedversatile potassium acetate (KAc) as the cathode buffer layer (CBL),electron transporting layer (ETL), and perovskite additive in all-inorganicCsPbI(2)Br PSCs, respectively. All the KAc-incorporated devicesyield higher efficiency than the control device. Especially, we achievethe interfacial and doping synergistic effects by introducing KAcCBL between SnO2 ETL and CsPbI2Br perovskite.For the interfacial effect, the KAc CBL can passivate the Sn-relateddefects and optimize the interfacial energy-level alignment at theSnO(2)/CsPbI2Br contact. For the doping effect,KAc is partially doped into CsPbI2Br during spin-coatingof the perovskite precursor solution due to its good solubility inthe solvent of perovskite precursor, which results in the passivationof uncoordinated Pb2+ in the perovskite layer. Owing tothe interfacial and doping synergistic effect, the power conversionefficiency (PCE) increases noticeably from 12.91% to 15.71% afterinserting KAc CBL. Furthermore, the device with KAc CBL exhibits superiorlong-term thermal stability. The findings offer a versatile materialto simultaneously passivate interfacial and bulk defects and thusenhance the performance of all-inorganic PSCs.