Reversible Oxidative p-Doping in 2D Tin Halide Perovskite Field-Effect Transistors

Tin (Sn) halide perovskites are promising materials for various electronic applications due to their favorable properties. However, facile interaction with atmospheric oxygen (O₂) often hinders the practical use of Sn-based perovskites, which is regarded as a major cause of undesired variations in their electrical and structural properties. Herein, we report the reversible p-doping in phenethylammonium tin iodide ((PEA)₂SnI₄) transistors when they are exposed sequentially to ambient and vacuum conditions. Exposure to ambient conditions induces p-doping effects that lead to a significant shift in the threshold voltage. Interestingly, we have found that the unintentionally p-doped (PEA)₂SnI₄ transistors can be fully restored by simply exposing them to vacuum, indicating a complete dedoping without any structural or operational degradation. Our first-principles calculations further support the observations by revealing that the doping by O₂ molecules occurs via occupying the interstitial sites that form acceptor levels close to the valence band maximum of (PEA)₂SnI₄.