Ordered-vacancy defect chalcopyrite ZnIn2Te4: A potential thermoelectric material with low lattice thermal conductivity

Abstract

An effective route towards commercializing thermoelectric devices is to explore materials with high conversion efficiency. This study investigates the thermoelectric properties of ZnIn2Te4 with the combination of first-principles calculations, Boltzmann transport theory and the modified Debye Callaway model. This vacancy-ordered defect chalcopyrite shows a direct band gap of 1.37 eV, obtained by mBJ functional with spin orbit coupling. The positive phonon dispersion curves ensure the thermodynamical stability of the material. Moreover, strong acoustic-optical coupling, Grüneisen parameter, and moderate phonon group velocity yielded the low lattice thermal conductivity (kL) of 1.46 W m−1 K−1 at 900 K. Owing to this low kL, the optimum thermoelectric figure of merit of 0.90 and 0.98 is obtained for p and n-type ZnIn2Te4. These findings will open the way for the experimentalists to attempt for its experimental realization.