Improved performance of perovskite solar cells via combining Pb–Sn alloying with the passivation effect of SnI2

Abstract

There are a large number of defects on the surface and grain boundaries of the perovskite layer, which is an important reason for the further development of perovskite solar cells (PSCs). In this work, an improved strategy is proposed. By introducing the additive SnI₂ into the antisolvent, not only is Pb–Sn alloyed perovskite formed, but SnI₂ as a passivation agent also successfully passivates the defects of the perovskite film. Through the dual effect of SnI₂, the crystallinity of the perovskite film is significantly improved, the charge recombination is inhibited, and the charge transfer efficiency is also significantly improved. The perovskite solar cells prepared with this perovskite film achieved a champion power conversion efficiency (PCE) of 20.9% with a fill factor (FF) of 74.3%, and benefitting from the improved quality of the perovskite film, the initial efficiency of 88% was maintained after exposing the device to air with a relative humidity of 30% for 1056 hours.