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

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.