Orientation Dependent Thermal Conductance in Single-Layer MoS2

TL;DR

This study reveals that the thermal conductance of single-layer MoS2 nanoribbons significantly depends on their orientation, with zigzag edges conducting heat more efficiently than armchair edges, due to differences in phonon transport channels.

Contribution

It provides a detailed analysis of orientation-dependent thermal conductivity in MoS2 nanoribbons using first-principles and Green's function methods, highlighting the underlying phonon transport mechanisms.

Findings

Zigzag MoS2 nanoribbons have higher thermal conductivity than armchair ones.

Fewer phonon transport channels in armchair nanoribbons cause lower thermal conductance.

Thermal conductivity in MoS2 nanoribbons is comparable to that of graphene.

Abstract

We investigate the thermal conductivity in the armchair and zigzag MoS$_{2}$ nanoribbons, by combining the non-equilibrium Green's function approach and the first-principles method. A strong orientation dependence is observed in the thermal conductivity. Particularly, the thermal conductivity for the armchair MoS$_{2}$ nanoribbon is about 673.6 Wm$^{-1}$K$^{-1}$ in the armchair nanoribbon, and 841.1 Wm$^{-1}$K$^{-1}$ in the zigzag nanoribbon at room temperature. By calculating the Caroli transmission, we disclose the underlying mechanism for this strong orientation dependence to be the fewer phonon transport channels in the armchair MoS$_{2}$ nanoribbon in the frequency range of [150, 200] {cm$^{-1}$}. Through the scaling of the phonon dispersion, we further illustrate that the thermal conductivity calculated for the MoS$_{2}$ nanoribbon is esentially in consistent with the superior thermal conductivity found for graphene.