Physical vapor deposition of methylammonium tin iodide thin films

Methylammonium tin halides have been identified as a substitute for the lead‐based perovskites in photovoltaic devices. We report the fabrication of CH3 NH3 SnI3 thin films using physical vapor deposition. The periodic deposition of SnI2 and CH3 NH3 I yields thin films that homogeneously cover areas as large as 100 cm2. The microscopic homogeneity of the layers causes a metallic reflectivity. Photoluminescence studies indicate that the density of states is inhomogeneously broadened. The films are stable as long as contact with air is avoided. Light‐induced degradation is marginal, even up to illumination levels that approach the dose expected for future photovoltaic devices. Image of a branch with leaves reflected by a 10 cm×10 cm MASnI3 layer, which illustrates the achieved surface quality. Physical vapor deposition is an attractive technological route toward large area thin films of metal organic halide perovskites. The deposition of methylammonium tin iodide yields layers with homogeneous stoichiometry across areas as large as 100 cm2 and a metal‐like reflectivity, which indicates homogeneity on microscopic scales. Photoluminescence studies show that the electronic density of states is inhomogeneously broadened and that the films withstand high illumination doses.