# Outstanding strength, optical characteristics and thermal conductivity of graphene-like BC$_3$ and BC$_6$N semiconductors

## TL;DR

This study introduces two novel graphene-like 2D materials, BC$_3$ and BC$_6$N, demonstrating exceptional mechanical strength, high thermal conductivity, and promising electronic and optical properties through first-principles calculations.

## Contribution

The paper reports the theoretical prediction and analysis of stability, mechanical, electronic, optical, and thermal properties of BC$_3$ and BC$_6$N monolayers, novel materials with outstanding features.

## Key findings

- BC$_3$ and BC$_6$N are dynamically stable with no imaginary phonon frequencies.
- BC$_6$N exhibits one of the highest thermal conductivities among 2D materials.
- BC$_3$ and BC$_6$N are semiconductors with distinct bandgap types and visible-range optical absorption.

## Abstract

Carbon based two-dimensional (2D) materials with honeycomb lattices, like graphene, polyaniline carbon-nitride (C$_3$N) and boron-carbide (BC$_3$) exhibit exceptional physical properties. On this basis, we propose two novel graphene-like materials with BC$_6$N stoichiometry. We conducted first-principles calculations to explore the stability, mechanical response, electronic, optical and thermal transport characteristics of graphene-like BC$_3$ and BC$_6$N monolayers. The absence of imaginary frequencies in the phonon dispersions confirm dynamical stability of BC$_3$ and BC$_6$N monolayers. Our first principles results reveal that BC$_3$ and BC$_6$N 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 BC$_6$N is one of the highest among all 2D materials. According to electronic structure calculations, monolayers of BC$_3$ and BC$_6$N are indirect and direct bandgap semiconductors, respectively. The optical analysis illustrate that the first absorption peaks along the in-plane polarization for single-layer BC$_3$ and BC$_6$N 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 BC$_3$ and BC$_6$N nanosheets and present them as promising candidates to design novel nanodevices.