High Thermoelectric Performance in Two-Dimensional Janus Monolayer Material WS-X (X = Se and Te).

Abhishek Patel,Rajeev Ahuja,Yogesh Sonvane,P B Thakor,Deobrat Singh

doi:10.1021/acsami.0c13960

Abstract

In the present work, Janus monolayers WSSe and WSTe are investigated by combining first-principles calculations and semiclassical Boltzmann transport theory. Janus WSSe and WSTe monolayers show a direct band gap of 1.72 and 1.84 eV at K-points, respectively. These layered materials have an extraordinary Seebeck coefficient and electrical conductivity. This combination of high Seebeck coefficient and high electrical conductivity leads to a significantly large power factor. In addition, the lattice thermal conductivity in the Janus monolayer is found to be relatively very low as compared to the WS2 monolayer. This leads to a high figure of merit (ZT) value of 2.56 at higher temperatures for the Janus WSTe monolayer. We propose that the Janus WSTe monolayer could be used as a potential thermoelectric material due to its high thermoelectric performance. The result suggests that the Janus monolayer is a better candidate for excellent thermoelectric conversion.

Highlights

The world’s energy demand is rapidly increasing due to factors like considerable growth in population, industrialization, development in technology, etc
The ability of thermoelectric conversion of thermoelectric material is summarized by the thermoelectric figure of merit (ZT), which is expressed as ZT = S2σT/κ, where S, σ, and κ represent the Seebeck coefficient, electrical conductivity, and thermal conductivity, respectively.[9−11] The thermal conductivity of the material is expressed as κ = κl + κe
The best thermoelectric performance measured until now has ZT values ranging from 2.5 to 2.8.11−14 The new material developed by the scientists of TU Wien has shown that the high efficiency ZT value lies between 5 and 6.15

Summary

■ INTRODUCTION

The world’s energy demand is rapidly increasing due to factors like considerable growth in population, industrialization, development in technology, etc. Until recently, these energy needs were being fulfilled with fossil fuels and other nonrenewable resources;[1] the massive consumption of such resources led to the unavailability of them. The new derivatives of two-dimensional (2D) materials, Janus 2D materials, have attracted considerable research attention due to their distinct properties. In 2013, the dynamical stability of MoSSe, WSSe, WSTe, and WSeTe was proved through a Received: August 3, 2020 Accepted: September 15, 2020 Published: September 15, 2020

■ COMPUTATIONAL METHODS

■ CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES