High-efficient thermoelectric materials: The case of orthorhombic IV-VI compounds

TL;DR

This study computationally evaluates orthorhombic IV-VI compounds, revealing their potential as high-efficiency thermoelectric materials due to favorable electrical and thermal properties, expanding beyond the well-known SnSe.

Contribution

It provides first-principles calculations of thermoelectric properties for GeS, GeSe, SnS, and SnSe, demonstrating their comparable or superior performance to SnSe.

Findings

GeS, GeSe, and SnS have large Seebeck coefficients.

All four compounds show low thermal conductivities.

They are promising candidates for high-efficiency thermoelectric applications.

Abstract

Improving the thermoelectric efficiency is one of the greatest challenges in materials science. The recent discovery of excellent thermoelectric performance in simple orthorhombic SnSe crystal offers new promise in this prospect [Zhao et al. Nature 508, 373 (2014)]. By calculating the thermoelectric properties of orthorhombic IV-VI compounds GeS,GeSe,SnS,and SnSe based on the first-principles combined with the Boltzmann transport theory, we show that the Seebeck coefficient, electrical conductivity, and thermal conductivity of orthorhombic SnSe are in agreement with the recent experiment. Importantly, GeS,GeSe,and SnS exhibit comparative thermoelectric performance compared to SnSe. Especially, the Seebeck coefficients of GeS,GeSe,and SnS are even larger than that of SnSe under the studied carrier concentration and temperature region. We also use the Cahill's model to estimate the lattice thermal conductivities at the room temperature. The large Seebeck coefficients, high power factors, and low thermal conductivities make these four orthorhombic IV-VI compounds promising candidates for high-efficient thermoelectric materials.