Relationship between Carrier Density and Precursor Solution Stirring for Lead-Free Tin Halide Perovskite Solar Cells Performance

The oxidation of tin halide perovskite precursor (THP) with the solvent dimethyl sulfoxide (DMSO) has intriguing drawbacks. We found that THP oxidation under progressive stirring can be hindered by the addition of GeI2. Subsequently, the stirring time of the precursor solution affects the carrier density and semiconducting properties of fabricated films, because DMSO can increase the oxidation induced carrier density. On the other hand, dimethylformamide (DMF) can suppress the oxidation induced carrier density. After 24 h, an efficiency of 10.26% is found when DMF is used and 7.12% is found when DMSO is used as a stirring solvent.