Thermoelectric properties of half-Heusler TaFeSb from first-principles electron-phonon scattering calculations

We investigate thermoelectrics transport properties of half-Heusler TaFeSb within the Boltzmann transport formalism, using first principles calculations of the electronic relaxation times. Our goal is to explore the microscopic origin of exceptionally high ZT values (up to 1.52 at 973 K) recently reported from the experimental measurements of transport properties of TaFeSb-based compounds. In particular, we focus on the effects arising from the electron-phonon interaction. For that we calculate corresponding scattering rates using Wannier-Fourier interpolation of electron-phonon matrix elements as well as the recently developed electron-phonon averaged (EPA) approximation. We discuss the likely mechanisms of high ZT in TaFeSb-based systems and possible ways to further improve thermoelectric properties of half-Heusler compounds.