Enhanced performance of perovskite solar cells via anti-solvent nonfullerene Lewis base IT-4F induced trap-passivation

Abstract

The defects at the surfaces and grain boundaries of organic–inorganic halide perovskite films are detrimental to both the efficiency and stability of perovskite solar cells. Here, we introduce an in situ method with a new nonfullerene small molecule (IT-4F) that can effectively passivate ionic defects of hybrid perovskites with their positively charged components, under-coordinated Pb²⁺, during the anti-solvent process of perovskite film formation. This efficient defect passivation reduces the charge trap density and increases the carrier recombination lifetime. Furthermore, it reduces the open-circuit-voltage deficit of the p–i–n-structured device, and boosts the efficiency to a value of 18.3%. Moreover, the defect healing also significantly enhances the stability of films under ambient conditions. Our findings provide an avenue for defect passivation to further improve both the efficiency and stability of perovskite solar cells.