Mixed Anion Semiconductor In₈S_2.82Te_6.18(Te₂)₃

Abstract

The new heteroanionic compound In8S2.82Te6.18(Te2)3 crystallizes in the monoclinic space group C2/c with lattice parameters a = 14.2940(6) Å, b = 14.3092(4) Å, c = 14.1552(6) Å, and β = 90.845(3)°. The three-dimensional (3D) framework of In8S2.82Te6.18(Te2)3 is composed of a complex 3D network of corner-connected InQ4 tetrahedra with three Te2 2– dumbbell dimers per formula unit. The optical bandgap is 1.12(2) eV and the work function is 5.15(5) eV. First-principles electronic structure calculations using density functional theory (DFT) indicate that this material has potential as a p-type thermoelectric material as it is a narrow bandgap semiconductor, incorporates several heavy elements, and has multiple overlapping bands near the valence band maximum.