Non-linear enhancement of thermoelectric performance of a TiSe2 monolayer due to tensile strain, from first-principles calculations

Abstract

Using first-principles density functional theory (DFT) calculations combined with the Boltzmann transport theory, we investigate the effect of strain on the electronic and thermoelectric transport properties of the 1T-TiSe₂ monolayer, a two-dimensional (2D) material, and compare it with the bulk phase within the PBE, LDA + U and HSE exchange–correlation functionals. It has been found that in this semimetallic material, under HSE, the electronic bandgap is changed from −0.22 to 0.12 to 0.39 eV with tensile strain increasing respectively from 0 to 2% and 4%. Accordingly this metal–insulator transition induced by strain causes a non-linear change in the electronic and thermoelectric properties of this material, leading to a high Seebeck coefficient and a power factor.