Small compressive strain-induced semiconductor–metal transition and tensile strain-enhanced thermoelectric properties in monolayer PtTe2

Abstract

Biaxial strain effects on the electronic structures and thermoelectric properties of monolayer are investigated by using generalized gradient approximation (GGA) plus spin–orbit coupling for the electron part and GGA for the phonon part. Calculated results show that a small compressive strain (about −3%) can induce semiconductor-to-metal transition, which can easily be achieved in experiment. Band convergence in the conduction bands is observed for unstrained , which can be removed by both compressive and tensile strain. Tensile strain can give rise to band convergence in the valence bands by changing the position of the valence band maximum, which can induce an enhanced Seebeck coefficient, and bring about high power factors. It is found that tensile strain can also reduce lattice thermal conductivity. More specifically, the lattice thermal conductivity at a strain of 4% can decrease by about 19% compared to the unstrained case at room temperature. According to the tensile strain effects on ZTe and lattice thermal conductivity, tensile strain can indeed improve the p-type efficiency of thermoelectric conversion. Our results demonstrate the potential of strain engineering in for applications in electronics and thermoelectricity.