Impact of solvent exposure on the structure and electronic properties of CH_3NH_3Pbl_(3-x)Cl_x mixed halide perovskite films

摘要

Organic semiconductor charge transport layers are important constituents of perovskite-based solar cells. To assess the suitability of potential solvents for the deposition of the charge transport layers on perovskite surfaces, the effect of solvent exposure on the properties of methyl ammonium lead mixed halide CH3NH3PbI3-xClx films is investigated by grazing incidence X-ray diffraction, atomic force microscopy, ultraviolet-visible absorption spectroscopy, and photoelectron spectroscopy. While exposure to dimethylformamide (DMF) and water instantly dissolves the perovskite film, exposure to chlorobenzene (CB) and chloroform (CF) does not detectably affect the perovskite bulk properties. However, the electronic properties of the perovskite surface are substantially modified by the solvent exposure, resulting in an increased work function and less n-type appearance.