High thermoelectric performance of Weyl semimetal TaAs

Highlights: • Anisotropic transport properties are observed in TaAs. • A maximum zT of 0.63 at 900 K is found for n-doping TaAs along zz direction. • An improved thermoelectric performance is expected when the size along zz direction is reduced. The existence of Weyl nodes predicted in TaAs has been confirmed by angle-resolved photoemission spectroscopy, which provides potential applications in thermoelectric devices due to the extraordinary transport properties of TaAs. By using first-principles calculations and semiclassical Boltzmann transport theory, we study the electrical transport properties of TaAs. High anisotropy is observed in the electrical transport of TaAs. The obtained Seebeck coefficients are in good agreement with experimental values. The lattice dynamics properties of TaAs are also investigated and the obtained phonon frequencies agree well with the measurements. The lattice thermal conductivity is calculated using the self-consistent iterative approach. Anisotropic lattice thermal conductivity is observed as well. Maximum thermoelectric figure of merit zT of 0.63 at 900 K is found for n-doping TaAs along zz direction. Finally, the size dependence of lattice thermal conductivity and corresponding thermoelectric properties are investigated for designing thermoelectric nanostructures. The work sheds light on the nature of the thermoelectric response of Weyl semimetal.