Exploring bonding nature, electronic, optical and thermoelectric properties of ternary compound Na2ZnCl4 via first-principles calculations

Abstract

• Structural studies of the orthorhombic phase Na 2 ZnCl 4 compound have been studied • The electronic properties of the compound, such as band structure and density of states signify its insulating nature with a wide - bandgap of 4.51 eV. • The analysis of the charge density distribution for this compound along the ( 2 1 ¯ 0 ) plane indicates partially ionic and partially covalent bond between atoms. • Various optical properties, including the absorption coefficient, dielectric function, energy loss function, reflectivity and refractive index were studied. • The results from the Figure of merit provide material applications in thermo-electric devices. First-principles calculations for orthorhombic Na 2 ZnCl 4 performed using Density Functional Theory (DFT) to analyze the structural, electronic, optical and thermoelectric properties using WIEN2k code. The exchange correlation of PBE (GGA) is used. Geometrical optimization is performed with c/a variation to find the optimized lattice constant which is in good agreement with the experimental results. Electronic property calculations, including the band structure and density of states (DOS) indicates that the compound is a wide-bandgap insulator (WBGI) with a bandgap of 4.51 eV. The bonding nature is determined from charge density plot. Thermoelectric studies provide the figure of merit for this compound is around 0.52 at 900 K. The calculated optical and thermoelectric properties demonstrate the application of these compound in optoelectronic and thermo-electric devices.