First–Principles Investigation of the Structural, Elastic, Electronic, and Optical Properties of α– and β–SrZrS(3): Implications for Photovoltaic Applications

Transition metal perovskite chalcogenides are attractive solar absorber materials for renewable energy applications. Herein, we present the first–principles screened hybrid density functional theory analyses of the structural, elastic, electronic and optical properties of the two structure modifications of strontium zirconium sulfide (needle–like α–SrZrS(3) and distorted β–SrZrS(3) phases). Through the analysis of the predicted electronic structures, we show that both α– and β–SrZrS(3) materials are direct band gaps absorbers, with calculated band gaps of 1.38, and 1.95 eV, respectively, in close agreement with estimates from diffuse–reflectance measurements. A strong light absorption in the visible region is predicted for the α– and β–SrZrS(3), as reflected in their high optical absorbance (in the order of 10(5) cm(−1)), with the β–SrZrS(3) phase showing stronger absorption than the α–SrZrS(3) phase. We also report the first theoretical prediction of effective masses of photo-generated charge carriers in α– and β–SrZrS(3) materials. Predicted small effective masses of holes and electrons at the valence, and conduction bands, respectively, point to high mobility (high conductivity) and low recombination rate of photo-generated charge carriers in α– and β–SrZrS(3) materials, which are necessary for efficient photovoltaic conversion.