Assessing Carrier Mobility, Dopability and Defect Tolerance in the Chalcogenide Perovskite BaZrS₃

The chalcogenide perovskite BaZrS₃ has attracted much attention as a promising solar absorber for thin-film photovoltaics. In this talk, we present our first-principles results on carrier transport and defect properties in this material. We find that BaZrS₃ has a phonon-limited electron mobility of 37 cm²/Vs comparable to that in halide perovskites but lower hole mobility of 11 cm²/Vs. The defect calculations, based on advanced hybrid density functional theory, indicate that BaZrS₃ is intrinsically n-type due to shallow sulfur vacancies, but that strong compensation by sulfur vacancies will prevent attempts to make it p-type. We also establish that BaZrS₃ is a defect-tolerant absorber with few low-formation-energy, deep intrinsic defects. Among the deep defects, sulfur interstitials are the strongest nonradiative recombination centers which in sulfur-rich conditions would limit the carrier lifetime to 10 ns. Our work highlights the material’s intrinsic limitations in carrier mobility and suggests suppressing the formation of sulfur interstitials to reach long carrier lifetime.