Inter-relationship of the Structural Properties of Quaternary Chalcogenides CuZn_2Ga(S/Se)_4: A First-Principles Study

摘要

Quaternary chalcogenides based on stannite I-II_2-III-VI_4 structure are the best potential candidates to overcome the current generation of solar harvesting materials. First-principles electronic structure simulations were performed on semiconducting CuZn_2Ga(S/Se)_4 (CZGS/Se) to understand the inter-relationship of the structural properties. These structures contain a cubic close packing (ccp) array of S/Se-centered tetrahedrons, coordinated by one Cu, two Zn and one Ga atom occupying one half of the ccp tetrahedral voids. The remarkable variations in the crystal structures are explained by the influence of ionic radii of various atoms. The electronic and optical properties calculated using hybrid functional (Heyd, Scuseria and Ernzerhof, HSE06) show a suitable band gap of 1.59 eV for CZGSe with high optical absorption. The current density and maximum upper limit of theoretical energy conversion efficiency (P(%)) of CZGSe is enhanced when compared to that of CZGS. Our results suggest that the stannite CZGSe structure could be a promising candidate for efficient earth-abundant thin-film solar cell applications.