Interface engineering with KI modifier enhances performance of CsPbBr3 perovskite solar cells

CsPbBr₃ perovskite solar cells (PSCs) have garnered widespread attention because of their remarkable environmental resistance and distinctive photoelectric properties. However, the presence of defects in the bulk perovskite grains and the ETL/PVK interface leads to significant non-radiative recombination, compromising the photoelectric performance and hindering further improvements of the devices. In this study, we present an interface engineering utilizing potassium iodide (KI) as an ETL/PVK interface modifier to improve perovskite films quality and modify the interface. The introduction of KI was observed to passivate interfacial defects and optimize energy levels. Additionally, KI plays a crucial role in reducing defects within perovskite films, particularly X vacancies, and optimizing morphology. Consequently, the device based on the KI-SnO₂ attains a champion PCE of 9.67 % with an outstanding V_OC of 1.60 V. Meanwhile, the devices demonstrate excellent stability as no performance degradation was observed after being stored in ambient conditions for 30 days.