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.