Electron-phonon scattering and thermoelectric transport in $p$-type PbTe from first principles

TL;DR

This paper develops a first principles model of electron-phonon scattering and thermoelectric transport in p-type PbTe, showing good agreement with experiments and highlighting the importance of valley degeneracy for thermoelectric performance.

Contribution

It introduces a detailed first principles model accounting for valley shifts and scattering mechanisms in PbTe, revealing the role of valley degeneracy in thermoelectric efficiency.

Findings

Longitudinal optical phonons dominate scattering in p-type PbTe.

L valleys primarily contribute to thermoelectric transport at 300 K.

Valley degeneracy enhances thermoelectric performance.

Abstract

We present a first principles based model of electron-phonon scattering mechanisms and thermoelectric transport at the L and $\Sigma$ valleys in <200b>$p$-type PbTe, accounting for their thermally induced shifts. Our calculated values of all thermoelectric transport parameters at room temperature are in very good agreement with experiments for a wide range of doping concentrations. Scattering due to longitudinal optical phonons is the main scattering mechanism in $p$-type PbTe, while scattering due to transverse optical modes is the weakest. The L valleys contribute most to thermoelectric transport at 300 K due to the sizeable energy difference between the L and $\Sigma$ valleys. We show that both scattering between the L and $\Sigma$ valleys and additional transport channels of the $\Sigma$ valleys are beneficial for the overall thermoelectric performance of $p$-type PbTe at 300 K. Our findings thus support the idea that materials with high valley degeneracy may be good thermoelectrics.