Pressure-driven thermoelectric properties of defect chalcopyrite structured ZnGaTe: study.

The pressure induced structural, electronic, transport, and lattice dynamical properties of ZnGaTe were investigated with the combination of density functional theory, Boltzmann transport theory and a modified Debye-Callaway model. The structural transition from 4̄ to 4̄2 occurs at 12.09 GPa. From the basic observations, ZnGaTe is found to be mechanically as well as thermodynamically stable and ductile up to 12 GPa. The direct band gap of 1.01 eV is inferred from the electronic band structure. The quantitative analysis of electron transport properties shows that ZnGaTe has moderate Seebeck coefficient and electrical conductivity under high pressure, which resulted in a large power factor of 0.63 mW m K (750 K). The ultralow lattice thermal conductivity (∼1 W m K at 12 GPa) is attributed to the overlapping of acoustic and optical phonon branches. As a result, the optimal figure of merit of 0.77 (750 K) is achieved by applying a pressure of 12 GPa. These findings support that ZnGaTe can be a potential p-type thermoelectric material under high pressure and thus open the door for its experimental exploration.