First principles study of thermoelectric properties of Li-based half-Heusler alloys

Abstract

Thermoelectric materials with good figures of merit are being sought for perpetually. In this paper, thermoelectric properties of LiYZ (Y=Be, Mg, Zn, Cd and Z=N, P, As, Sb, Bi) have been studied employing first principles density functional theory based calculations followed by the solutions of Boltzmann transport equations under relaxation time approximation. Calculated Seebeck coefficients are quite large and are comparable to that of PbTe, a well known thermoelectric material. Doping dependence of the transport coefficients are calculated under rigid band approximation. Except LiZnSb, all the compounds have larger values of power factors for p-type doping than those for n-type doping. The optimal p- and n-type doping levels corresponding to the maximum thermoelectric power factors of these compounds have been calculated, which are important parameters for guiding experimental works.