Electron-phonon coupling and thermoelectric transport in n-type PbTe

PbTe is an important thermoelectric material for power generation applications due to its high conversion efficiency and reliability [1]. PbTe shows a shift of the electronic bandgap with temperature that is opposite to the majority of direct gap semiconductors, i.e. the gap increases with temperature [2]. In this work, we study the temperature dependence of the electronic structure and thermoelectric properties of PbTe. We perform density functional theory and density functional perturbation theory calculations [3] in the local density approximation to calculate electronic and phonon bands. We use Wannier interpolation scheme to calculate electron-phonon matrix elements [4]. Using this information, we build accurate models of electronic and phonon bands, and deformation potentials from first principles. By solving the Boltzmann equation in the momentum relaxation time approximation, we calculate the mobility and thermoelectric transport properties of PbTe. Our results are in good agreement with experiments. We find that the temperature dependence of the gap has a substantial effect on thermoelectric transport in PbTe.