Quasiparticle and Optical Properties of Two Dimensional C₃N and C₃B

Highly ordered honeycomb structures carbon nitride (C₃N) and boron carbide (C₃B) are emerging 2D materials that have attracted much interest. In this work, we present fully converged GW results for monolayers C₃N and C₃B, and the C₃N/C₃B bi-layer heterostructure. The converged GW bandgap of monolayer C₃N (C₃B) is about 1.5 (2.6) eV; these results call for future experimental verifications. We have also carried out highly converged GW+BSE calculations of these systems. The nearly parallel valence and conduction states give rise to extremely strong optical absorption, suggesting potentials for future 2D optoelectronics applications. We will also report details of the excitonic structures of these materials.