Additive Combining Passivator for Inverted Wide-Bandgap Perovskite Solar Cells with 22% Efficiency and Reduced Voltage Loss

Wide-bandgap (WBG) perovskite solar cells (PSCs) play a crucial role in tandem devices. However, the severe nonradiative recombination that occurs at the interface between perovskite and electron transport layer (ETL) leads to excessive open-circuit voltage ( V OC ) loss, which hinders the further improvement of the photovoltaic conversion efficiency (PCE). To mitigate the V OC loss in WBG PSCs, the defects in grains and grain boundaries are reduced as well as the energy-level alignment between perovskite layer and ETL, so as to improve the carrier collection efficiency, is optimized. Herein, potassium thiocyanate is introduced as an additive and 2-thiophenethylammonium bromide (TEABr) is used to passivate perovskite/C 60 interface. The synergistic treatment reduces the defect density and prolongs the carrier lifetime, implying that nonradiative recombination is effectively suppressed. Meanwhile, the energy-level alignment of the perovskite and C 60 is optimized, leading to the improvement of V OC . Finally, WBG PSCs with a bandgap of 1.68 eV achieve a V OC of 1.22 V (with a V OC loss of 0.46 V) and a PCE of 22.02%.