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

Abstract

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.