Giant thermoelectric figure of merit in multivalley high-complexity-factor LaSO

TL;DR

This paper reports a record-high thermoelectric figure of merit in LaSO, achieved through detailed ab initio calculations of electronic and phononic properties, highlighting the role of band complexity and potential doping strategies.

Contribution

The study introduces a giant thermoelectric figure of merit in LaSO, combining advanced ab initio calculations with thermal conductivity modeling to explain the high performance.

Findings

Achieved ZT up to 6 at 1100 K in LaSO.

Identified large band complexity as key to high power factor.

Suggested potential n-type dopant based on calculations.

Abstract

We report a giant thermoelectric figure of merit $ZT$ (up to 6 at 1100 K) in $n$-doped lanthanum oxysulphate LaSO. Thermoelectric coefficients are computed from ab initio bands within Bloch-Boltzmann theory in an energy-, chemical potential- and temperature-dependent relaxation time approximation. The lattice thermal conductivity is estimated from a model employing the ab initio phonon and Gr\"uneisen-parameter spectrum. The main source of the large $ZT$ is the significant power factor which correlates with a large band complexity factor. We also suggest a possible $n$-type dopant for the material based on ab initio calculations.