Superior lattice thermal conductance of single-layer borophene

Abstract

By way of the non-equilibrium Green's function simulations and first-principles calculations, we report that borophene, a single layer of boron atoms that was fabricated recently, possesses an extraordinarily high lattice thermal conductance in the ballistic transport regime, which even exceeds graphene. In addition to the obvious reasons of light mass and strong bonding of boron atoms, the superior thermal conductance is mainly rooted in its strong structural anisotropy and unusual phonon transmission. For low-frequency phonons, the phonon transmission within borophene is nearly isotropic, similar to that of graphene. For highfrequency phonons, however, the transmission is one-dimensional, that is, all the phonons travel in one direction, giving rise to its ultra-high thermal conductance. The present study suggests that borophene is promising for applications in efficient heat dissipation and thermal management, and also an ideal material for revealing fundamentals of dimensionality effect on phonon transport in ballistic regime.

2D Boron Sheets: Structure, Growth, and Electronic and Thermal Transport Properties

“…Tasfack and Yakobson also studied the ballistic thermal transport of δ 6 borophene . The results of phonon thermal conductance agreed well with that from Zhou et al…”

“…Due to the high anisotropic and polymorphic structures, the thermal conductivity of borophene changes a lot in different structures and directions. Thermal conductance of borophene in the ballistic transport is supported to be higher than that of graphene; while the thermal conductivity of borophene in the diffusion transport is calculated to about 2−3 orders lower than that of graphene . The electron in borophene has larger contribution to the thermal transport comparing with that in graphene .…”

“…For β 12‐ borophene without strain, it is unexpected to be unstable due to the imaginary modes around Γ point along the Γ– X and Γ– Y directions . However, only 1% in‐plane tensile strain can eliminate negative phonon frequency to stabilize it . Therefore, β 12‐ borophene is highly to be stabilized by a suitable substrate.…”

“…Borophene possesses amazing phonon thermal conductance, which is even higher than graphene according to theoretical analyses. Zhou et al studied the phonon thermal conductance of δ 6 borophene . They found that lattice thermal conductance of δ 6 borophene along the armchair direction is 7.8 nW K −1 nm −2 at 300 K, which is almost twice the thermal conductance of graphene.…”

“…Interestingly, borophene was expected to have good thermal transport property comparable with graphene . Due to the high anisotropic and polymorphic structures, the thermal conductivity of borophene changes a lot in different structures and directions.…”