Mechanism of anisotropic in-plane thermal conductivity in two- dimensional nanoribbons

Y Dong and MP Huang and Y Tao and R Deng and H Cheng and YX Zhang and X Zhang, INTERNATIONAL JOURNAL OF THERMAL SCIENCES, 217, 110072 (2025).

DOI: 10.1016/j.ijthermalsci.2025.110072

The growing demand for two-dimensional (2D) nanodevices with long-term stability and optimal performance has brought in-plane thermal conductivities (IPTCs) of 2D materials into focus. This is due to their strong potential for efficient thermal management. In this study, we systematically investigate the IPTCs of graphene nanoribbons (GNRs) and black phosphorus nanoribbons (BPNRs) using non-equilibrium molecular dynamics simulations. The IPTCs of both nanoribbons exhibit a considerable anisotropy, with the highest IPTCs observed in the zigzag direction and the lowest in the armchair direction. This anisotropy is characterized by substantial differences, with values of 38.3 % for GNR and 72.8 % for BPNR, attributed to the oriented phonon group velocity derived from phonon dispersion analysis. Both zigzag and armchair IPTCs increase with system size, and the infinite-size IPTCs are obtained through inverse fitting. Additionally, we observe a decrease in IPTC with increasing temperature, attributed to enhanced phonon-phonon scattering. Notably, the anisotropic IPTC difference diminishes at higher temperatures. Finally, the disparate structural symmetries between GNR and BPNR underpin the discrepancies in their heat flux distributions, with the orthogonal lattice of BP amplifying the directional variations in phonon velocities. This study provides significant theoretical insights into the anisotropic thermal properties, facilitating the design of efficient heat transport channels in 2D nanoribbon-based nanodevices.

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