Excitonic structure and extremely strong and narrow optical absorption of C₃N and C₃B monolayer

The graphene-like 2D materials C₃N and C₃B have attracted increasing attention due to their various potential applications. Compared with graphene, C₃N is electron rich, whereas C₃B is electron deficient. Both materials have a moderate band gap and possess nearly parallel valence and conduction bands [1,2] which may be beneficial for strong optical absorption. In this work, we have carried out fully converged calculations to investigate the excitonic structures and optical properties of C₃N and C₃B within the GW and Bethe-Salpeter equation (BSE) approach. We find that parallel band edges give rise to extremely strong and narrow excitonic absorption. Details of the excitonic structure will also be discussed.

[1]       Y. Wu, W. Xia, W. Gao, F. Jia, P. Zhang, and W. Ren, 2D Materials 6, 015018 (2018).

[2]       Y. Wu, W. Xia, Y. Zhang, W. Zhu, W. Zhang, and P. Zhang, Physical Review Applied 14, 014073 (2020).