Layered conjugated porous fused aromatic network structures of two-dimensional carbon nitride: a first-principles calculation of optoelectronic properties

Very recently, the two-dimensional (2D) structure of poly-benzimidazobenzophenanthroline (C₅N) has been effectively synthesized [Javeed Mahmood et al., Adv. Mater. 2021, 33, 2,004,707]. Inspired by interesting experimental findings on 2D layered C₅N structures, we employ DFT study to examine the electronic, structural, and optical features of C₅N in bulk, bilayer, and monolayer honeycomb crystal configurations. The obtained results demonstrate that all configurations of the C₅N structures have a strong bond network with cohesive energies comparable to graphene. In the ground state, the C₅N bulk, bilayer and monolayer honeycomb crystal structures are a semiconductor. It is found that the bandgap of the C₅N structures slightly increases with the decrease in the number of layers. The optical properties indicate the bulk structure possesses a greater capacity to absorb a broad range of visible light compared to the monolayer and bilayer.