Differing vibrational properties of halide and chalcogenide perovskite semiconductors and impact on optoelectronic performance

There is motivation to develop materials with photovoltaic performance comparable to halide perovskites but without the drawbacks of instability and toxicity. Chalcogenide perovskites are interesting because they have a tunable direct band gap and are very stable, but their optoelectronic properties are not yet well understood. This study of Raman and photoluminescence spectroscopy of BaZrS₃ and CsPbBr₃ single-crystal samples reveals differences in their vibrational properties and explores how these differences affect nonradiative recombination rates. The results suggest that the usefulness of chalcogenide perovskites for photovoltaics will hinge on continued progress in defect control.