An optimum thermoelectric figure of merit using Ge2Se2 monolayer: An ab-initio approach

Abstract

It is found that many two-dimensional chalcogenides are exhibiting a superlative thermoelectric behavior because of their versatile characters in terms of stability, conductivity, bandgap tunability, etc. In this paper, the thermoelectric properties of monolayer Ge2Se2 have been calculated using first-principles calculations with all involved electrical and thermal transport properties in the parameter-free framework. It has been found that the Ge2Se2 offers a bandgap of 1.13 eV with a sufficiently high thermoelectric coefficient. The thermoelectric transport parameters have been calculated by solving the linearized Boltzmann Transport Equation and found optimum to qualify for good thermoelectric materials. The investigated material exhibit outstanding thermoelectric performance in terms of an ultra low lattice thermal conductivity of the order of 0.5 Wm−1K−1 and TE Figure of merit around two (2) at 1000 K. For better accuracy in results, we employed hybrid exchange–correlation (HSE06) throughout the calculations and, instead of approximating the relaxation time, computed the accurate relaxation time using the deformation potential approach. The research findings prove its excellent behavior and worthy guideline for the experimentalists looking for materials with high FoM to design thermoelectric devices.