Anisotropic and high thermal conductivity in monolayer quasi-hexagonal fullerene: A comparative study against bulk phase fullerene

Abstract

Recently a novel two-dimensional (2D) C60 based crystal called quasi-hexagonal-phase fullerene (QHPF) has been fabricated and demonstrated to be a promising candidate for 2D electronic devices [Hou et al. Nature 606, 507-510 (2022)]. We construct an accurate and transferable machine-learned potential to study heat transport and related properties of this material, with a comparison to the face-centered-cubic bulk-phase fullerene (BPF). Using the homogeneous nonequilibrium molecular dynamics and the related spectral decomposition methods, we show that the thermal conductivity in QHPF is anisotropic, which is 140±30 W/mK at 300 K in the direction parallel to the cycloaddition bonds and 100 ± 20 W/mK in the perpendicular in-plane direction. By contrast, the thermal conductivity in BPF is isotropic and is only 0.45 ± 0.05 W/mK. We show that the inter-molecular covalent bonding in QHPF plays a crucial role in enhancing the thermal conductivity in QHPF as compared to that in BPF. The heat transport properties as characterized in this work will be useful for the application of QHPF as novel 2D electronic devices.

Stability and Strength of Monolayer Polymeric C60

“…The two-step structure relaxation mimics the experimental procedure to remove the charged ions introduced during synthesis. 1,4 The computed lattice constants for all three phases are given in Table 1, which are in good agreement with previous results, 10,11,15 therefore confirming the reliability of the present calculations.…”