Accelerated screening of thermoelectric materials by first-principles computations of electron-phonon scattering

TL;DR

This paper introduces a simplified first-principles method for predicting thermoelectric material performance by accurately computing electron-phonon interactions, enabling efficient screening and discovery of promising materials.

Contribution

A novel, computationally efficient approach for calculating electronic transport properties that improves accuracy and transferability over existing methods.

Findings

Electron relaxation time varies significantly with composition and carrier concentration.

Effective electron mass is identified as the key descriptor for thermoelectric performance.

The method is validated with experimental data and applied to half-Heusler alloys.

Abstract

Recent discovery of new materials for thermoelectric energy conversion is enabled by efficient prediction of materials' performance from first-principles, without empirically fitted parameters. The novel simplified approach for computing electronic transport properties is described, which achieves good accuracy and transferability while greatly reducing complexity and computation cost compared to the existing methods. The first-principles calculations of the electron-phonon coupling demonstrate that the energy dependence of the electron relaxation time varies significantly with chemical composition and carrier concentration, suggesting that it is necessary to go beyond the commonly used approximations to screen and optimize materials' composition, carrier concentration, and microstructure. The new method is verified using high accuracy computations and validated with experimental data before applying it to screen and discover promising compositions in the space of half-Heusler alloys. By analyzing data trends the effective electron mass is identified as the single best general descriptor determining material's performance. The Lorenz number is computed from first principles and the universality of the Wiedemann-Franz law in thermoelectrics is discussed.