Thermoelectric Properties of ZnO Wurtzite Structure by Density Functional Theory

ZnO wurtzite belongs to the hexagonal structure with an a/c ratio of 1.613, and it has an energy bandgap of approximately 3.37 eV and an exciton binding energy of 60 meV at room temperature. The investigation of this material began with geometry optimization using Density Functional Theory. The geometry optimization process using the Generalized Gradient Approximation with Perdew-Burke-Ernzerhof functional (GGA-PBE) exchange-correlation energy was performed to obtain lattice parameters a = b = 3.286 Å and c = 5.301 Å. Then, to determine the value of bandgap energy, simulations were carried out using GGA-PBE and GGA-PBE+Hubbard correction (U) exchange-correlation energies, resulting in a bandgap value of 3.37 eV. Further analysis of the thermoelectric properties was conducted using the semi-classical Boltzmann method at temperatures of 300K, 400K, and 500K. This yielded the highest figure of merit value for Wurtzite ZnO material, reaching 1 at 500K. These values indicate that the thermoelectric properties of ZnO with a wurtzite structure are close to optimal (ZT ~1).