Elastic, Optical, and Thermoelectric Properties of 2D Square Lattice and Hexagonal Zinc Chalcogenides under First‐Principles Calculations

Abstract

Herein, elastic, optical, and thermoelectric properties of zinc chalcogenides with 2D square lattice and hexagonal phases [s‐ and h‐ZnX (X = GrVI)] are reported. The s‐ZnX and h‐ZnX structures are achieved to be dynamically stable, according to the phonon dispersion studies. All s‐ and h‐ZnX compounds are found to be semiconductor, with direct and indirect bandgaps ranging from 0.81 to 2.77 eV under PBE and 1.70 to 4.15 eV by HSE06 calculations. The effective mass, mobility, and relaxation time of electron and hole carriers in the band structures of s‐ and h‐ZnX are investigated to gain a better insight of these materials. In addition to the phonon dispersion analysis, their mechanical stability in terms of elastic properties is evaluated, and the resulting elastic parameters validate their mechanical stability. The optical properties of s‐ and h‐ZnX are inspected in the occurrence of field polarizations across parallel and perpendicular directions. At room temperature, s‐ZnTe compound has an optimum figure of merit (ZT) value, indicating it as the superlative thermoelectric material in the entire series. These compounds may also be explored in ultraviolet lasers, solar cells, electronic image displays, high‐density optical memory, photodetectors, and solid‐state laser devices.