Extended Data Fig. 9: In situ XPS depth profile studies of different crystal structures.
From: A fabrication process for flexible single-crystal perovskite devices
In the single-crystal sample, only the surface areas are easy to be oxidized, indicating that the self-doping in deep areas away from the surface is relatively slow. In the polycrystalline sample, the oxidation is much faster in deep areas compared with the single-crystal samples, indicating that the grain boundaries facilitate the oxidation process.
