Abstract:
Tin-based perovskite solar cells offer a less toxic alternative to their lead-based
counterparts. Despite their promising optoelectronic properties, their performances still lag
behind, with the highest power conversion efficiencies reaching around 15%. This efficiency
limitation arises primarily from electronic defects leading to self-p-doping and stereochemical
activity of the Sn(II) ion, which distorts the atomic arrangement in the material. In this study, we
investigate the effect of strontium doping in tin-based perovskite on the distortion of the
material’s structure and its optoelectronic properties. Using a combination of Density Functional
Theory calculations and experiments, we demonstrate that strontium doping reduces p-doping
and structural strain. This approach improves the efficiency from 6.3% in undoped devices to
7.5% in doped devices without relying on dimethyl sulfoxide, a harmful solvent for tin-based
perovskites. This method could enable precise control of tin off-centering and self-p-doping,
advancing the development of efficient and stable tin perovskite solar cells.
