Effects of strontium doping on the morphological, structural, and photophysical properties of FASnI3 perovskite thin films

Doping engineering has been an effective technique applied extensively to enrich semiconductors and modulate their fundamental properties for electronic and optoelectronic applications. In this work, we report the influence of strontium (Sr) doping on solution-processed formamidinium tin iodide (FASnI3) perovskite thin films. We show that the addition of the Sr2+ dopant to the host perovskite drastically changes the morphology of the material but has no significant effect on the structural phase for doping concentrations lower than 10%. Using photoluminescence spectroscopy, we showed that for doping contents below 15%, the film is heterogeneously doped and strontium predominantly resides at the surface of the film. Above 15% of Sr, the bulk of the material is significantly doped. Our results show that Sr doping into FASnI3 perovskite can be a route for the attainment of new perovskites with interesting physical properties.