Single step deposition of Cs2SnIxCl6-x thin films with uniform morphology, composition and high air stability

The present work reports single step spray deposition of cesium tin mixed halide perovskite thin films using a precursor solution containing cesium chloride (CsCl) tin chloride (SnCl2) and iodine powder. At the optimized spray conditions, the role of solvents, substrate temperature and iodine concentration on the structure and properties of the perovskite films were investigated. X-ray diffraction patterns and Raman spectra showed that the thin films were Cs2SnIxCl6-x a mixed halide double perovskite having cubic crystal structure. The elemental composition and their chemical states were determined using X-ray photoelectron spectroscopy. The Cs2SnIxCl6-x perovskite thin films showed bandgap values ranging from 3.1 to 1.5 eV as x varied from 0 to 0.25. Further, the films showed uniform and compact morphology with good ambient air stability. Our results demonstrated that spray deposition is a reproducible technique to synthesize stable inorganic lead-free perovskite thin films.