Junhyoung Park, Andrea Olivati, Mirko Prato, Min Kim, Annamaria Petrozza
High Resolution Image Download MS PowerPoint Slide Coevaporation of formamidinium tin triiodide (FASnI 3 ) precursors, without any additives or reducing agents, leads to the growth of a highly crystalline thin films which show a bandgap around 1.31 eV, closely matching the theoretical value predicted from the ideal single crystal structure of FASnI 3 . The polycrystalline thin film presents a lower tendency toward Sn 2+ to Sn 4+ oxidation and highly reduced tendency toward self-doping, demonstrating, overall, an improved resistance to defects formation. These findings suggest solvent-free coevaporation processes as a promising route for high quality Sn-based perovskite polycrystalline thin films.