Thermoelectric properties of orthorhombic group IV-VI monolayers from the first-principles calculations

TL;DR

This study uses first-principles calculations to evaluate the thermoelectric properties of orthorhombic group IV-VI monolayers, revealing their potential for efficient thermoelectric devices with diverse anisotropic behaviors.

Contribution

It provides a comprehensive first-principles analysis of thermoelectric properties of specific 2D monolayers, highlighting their anisotropic behaviors and potential advantages over other 2D materials.

Findings

GeS shows strong anisotropy in thermoelectric properties.

SnS and SnSe exhibit high thermoelectric efficiency.

Certain monolayers outperform other 2D materials in thermoelectric performance.

Abstract

Two-dimensional (2D) materials may have potential applications in thermoelectric devices. In this work, we systematically investigate the thermoelectric properties of orthorhombic group IV-VI monolayers $\mathrm{AB}$ (A=Ge and Sn; B=S and Se) by the first-principles calculations and semiclassical Boltzmann transport theory. The spin-orbit coupling (SOC) is included to investigate their electronic transport, which produces observable effects on power factor, especially for n-type doping. According to calculated $ZT$, the four monolayers exhibit diverse anisotropic thermoelectric properties, although they have similar hinge-like crystal structure. The GeS along zigzag and armchair directions shows the strongest anisotropy, while SnS and SnSe show mostly isotropic efficiency of thermoelectric conversion, which can be understood by the strength of anisotropy of their respective power factor, electronic and lattice thermal conductivities. Calculated results show that $ZT$ for different carriers of n- and p-type has little difference for GeS, SnS and SnSe. It is found that GeSe, SnS and SnSe show better thermoelectric performance compared to GeS in n-type doping, and SnS and SnSe exhibit higher efficiency of thermoelectric conversion in p-type doping. Compared to a lot of 2D materials, orthorhombic group IV-VI monolayers $\mathrm{AB}$ (A=Ge and Sn; B=S and Se) may possess better thermoelectric performance due to higher power factor and lower thermal conductivity. Our work would be beneficial to further experimental study.