Outstanding strength, optical characteristics and thermal conductivity of graphene-like BC3 and BC6N semiconductors

Abstract

Carbon based two-dimensional (2D) materials with honeycomb lattices, like graphene, polyaniline carbon-nitride (C3N) and boron-carbide (BC3) exhibit exceptional physical properties. On this basis, we propose two novel graphene-like materials with BC6N stoichiometry. We conducted first-principles calculations to explore the stability, mechanical response, electronic, optical and thermal transport characteristics of graphene-like BC3 and BC6N monolayers. The absence of imaginary frequencies in the phonon dispersions confirm dynamical stability of BC3 and BC6N monolayers. Our first principles results reveal that BC3 and BC6N present high elastic moduli of 256 and 305 N/m, and tensile strengths of 29.0 and 33.4 N/m, with room temperature lattice thermal conductivities of 410 and 1710 W/m.K, respectively. Notably, the thermal conductivity of BC6N is one of the highest among all 2D materials. According to electronic structure calculations, monolayers of BC3 and BC6N are indirect and direct bandgap semiconductors, respectively. The optical analysis illustrate that the first absorption peaks along the in-plane polarization for single-layer BC3 and BC6N occur in the visible range of the electromagnetic spectrum. Our results reveal outstandingly high mechanical properties and thermal conductivity along with attractive electronic and optical features of BC3 and BC6N nanosheets and present them as promising candidates to design novel nanodevices.