Vapor incubation of FASnI3 films for efficient and stable lead-free inverted perovskite solar cells

Abstract

Tin perovskites with a narrow bandgap and high carrier mobility are highly attractive for environmentally friendly perovskite solar cells (PSCs), but the Sn-based PSCs are still less efficient and stable owing to the less perfect tin perovskite films. Here, we report a simple and efficient method to produce high-quality FASnI₃ films by establishing a solvent vapor environment without using additional additives to manipulate both the nucleation and crystal growth of perovskites at the very early stage of perovskite formation. The smooth morphology, large grain size and low trap state density of the tin perovskite films in preferred orientations were realized. Sn-based inverted PSCs show power conversion efficiency over 10% along with high device stability that retains 83 and 82% of initial performances for 600 h under continuous illumination and for 1000 h in a N₂ environment. These performances, which are among the best results of FASnI₃-based PSCs, demonstrate the impressive advantages of the vapor-incubation strategy in preparing preferred perovskite films for high-performance lead-free devices.