Strain-induced enhancement of thermoelectric performance in a ZrS2 monolayer

TL;DR

Applying biaxial tensile strain to ZrS2 monolayers significantly enhances their thermoelectric efficiency by increasing the Seebeck coefficient and reducing thermal conductivity, achieving a ZT value of 2.4 at 6% strain.

Contribution

This study demonstrates strain engineering as an effective method to improve thermoelectric performance in ZrS2 monolayers using first-principles calculations.

Findings

ZT value increases to 2.4 at 6% strain

Seebeck coefficient significantly enhanced by strain

Thermal conductivity reduced due to phonon softening

Abstract

The increase of a thermoelectric material's figure of merit (ZT value) is limited by the interplay of the transport coefficients. Here we report the greatly enhanced thermoelectric performance of a ZrS2 monolayer by the biaxial tensile strain, due to the simultaneous increase of the Seebeck coefficient and decrease of the thermal conductivity. Based on the first-principles calculations combined with the Boltzmann transport theory, we predict the band gap of the ZrS2 monolayer can be effectively engineered by the strain and the Seebeck coefficient is significantly increased. The thermal conductivity is reduced by the applied tensile strain due to the phonon softening. At the strain of 6%, the maximal ZT value of 2.4 is obtained for the p-type doped ZrS2 monolayer at 300 K, which is 4.3 times larger than that of the unstrained system.