First-principles study on phonon transport properties of MoTe2 and WTe2 monolayers in different phases br

Phase engineering of two-dimensional (2D) transition metal dichalcogenides (TMDC) monolayer is a key method for manipulating the lattice thermal conductivity. In this paper, we investigate the phonon thermal transport properties of MoTe2 and WTe2 monolayers with H and T ' phases (H-TMDC and T '-TMDC) via first-principles calculations. H-MoTe2 and H-WTe2 monolayers have isotropic lattice thermal conductivities, whereas the lattice thermal conductivities of T '-MoTe2 and T '-WTe2 monolayers are highly anisotropic. Meanwhile, in comparison with the H phase, the maximal lattice thermal conductivity in T ' phase has a reduction of 83.85% and 77.92% at 300 K for MoTe2 and WTe2 monolayers, respectively. Furthermore, we observe that phonon heat capacities and phonon lifetimes of T '-TMDC monolayers are lower than those of H-TMDC monolayers, while the phonon group velocities of T '-TMDC monolayers are larger. Hence, the competitive relationship among these parameters leads to a lower lattice thermal conductivity of the T '-TMDC monolayer. In addition, lower critical phonon MFPs (mean free path) of T '-TMDC monolayers prove that the lattice thermal conductivity has a weaker size dependence. These findings demonstrate that MoTe2 and WTe2 monolayers with different phases have a great potential in 2D nanoelectronic devices.

Automated summary

In this paper, the thermal transport properties of MoTe2 and WTe2 monolayers with different phases were investigated, showing different lattice thermal conductivities and phonon thermal transport characteristics. The findings suggest the potential applications of these monolayers in two-dimensional nanoelectronic devices.