First-principles study of the thermoelectric properties of Zintl compound KSnSb

TL;DR

This study uses first-principles calculations and Boltzmann transport theory to predict that the Zintl compound KSnSb exhibits high thermoelectric efficiency with a ZT of about 2.6 at 800 K, due to its unique structure.

Contribution

It demonstrates the potential of Zintl compounds for thermoelectric applications through detailed theoretical analysis.

Findings

ZT value of ~2.6 at 800 K

Large Seebeck coefficient from multi-valley bands

Very low lattice thermal conductivity

Abstract

The unique structure of Zintl phase makes it an ideal system to realize the concept of phonon-glass and electron-crystal in the thermoelectric community. In this work, by combining first-principles calculations and Boltzmann transport theory for both electrons and phonons, we demonstrate that the ZT value of Zintl compound KSnSb can reach ~2.6 at 800 K. Such extraordinary thermoelectric performance originates from the large Seebeck coefficient due to multi-valley band structures and particularly very small lattice thermal conductivity caused by mixed-bond characteristics.