Thermal transport in two-dimensional C3N/C2N superlattices: A molecular dynamics approach

TL;DR

This study uses molecular dynamics to explore how the thermal conductivity of 2D C3N/C2N superlattices varies with structural parameters, revealing the interplay of phonon scattering and wave interference effects.

Contribution

It provides new insights into the thermal transport mechanisms in 2D superlattices, highlighting the effects of interface density and phonon scattering on thermal conductivity.

Findings

Minimum thermal conductivity of 23.2 W/m·K at 5.2 nm period

Thermal conductivity increases with superlattice period at long lengths

Wave interference reduces thermal conductivity at short lengths

Abstract

Nanostructured superlattices have been the focus of many researchers due to their physical and manipulatable properties. They aim to find promising materials for new electronic and thermoelectric devices. In the present study, we investigate the thermal conductivity of two-dimensional (2D) C3N/ C2N superlattices using non-equilibrium molecular dynamics. We analyze the dependence of thermal conductivity on the total length, temperature, and the temperature difference between thermal baths for the superlattices. The minimum thermal conductivity and the phonon mean free path at a superlattice period of 5.2 nm are 23.2W/m.K and 24.7 nm, respectively. Our results show that at a specific total length, as the period increases, the number of interfaces decreases, thus the total thermal resistance decreases, and the effective thermal conductivity of the system increases. We found that at long lengths (L_x >80 nm), the high-frequency and low-wavelength phonons are scattered throughout the interfaces, while at short lengths, there is a wave interference that reduces the thermal conductivity. The combination of these two effects, i.e., the wave interference and the interface scattering, is the reason for the existence of a minimum thermal conductivity in superlattices.