Earth-abundant and Non-toxic SiX (X=S, Se) Monolayers as Highly Efficient Thermoelectric Materials

TL;DR

This paper proposes SiS and SiSe monolayers as highly efficient, non-toxic, and earth-abundant thermoelectric materials with high ZT values, due to their low thermal conductivity and high power factors, suitable for large-scale applications.

Contribution

It introduces SiS and SiSe monolayers as novel thermoelectric materials with superior performance, emphasizing their low toxicity, abundance, and promising thermoelectric efficiency.

Findings

SiS and SiSe monolayers have low thermal conductivities similar to SnSe.

They exhibit high thermoelectric figure of merit (ZT) exceeding 1 or 2.

Their two-dimensional structure contributes to high thermal power factors.

Abstract

Current thermoelectric (TE) materials often have low performance or contain less abundant and/or toxic elements, thus limiting their large-scale applications. Therefore, new TE materials with high efficiency and low cost are strongly desirable. Here we demonstrate that, SiS and SiSe monolayers made from non-toxic and earth-abundant elements intrinsically have low thermal conductivities arising from their low-frequency optical phonon branches with large overlaps with acoustic phonon modes, which is similar to the state-of-the-art experimentally demonstrated material SnSe with a layered structure. Together with high thermal power factors due to their two-dimensional nature, they show promising TE performances with large figure of merit (ZT) values exceeding 1 or 2 over a wide range of temperatures. We establish some basic understanding of identifying layered materials with low thermal conductivities, which can guide and stimulate the search and study of other layered materials for TE applications.