Phenyl- and naphthyl-type heteroatom substitution blocks in naphthylene-γ: A DFT study

Two-dimensional naphthylene-γ is a recently proposed carbon allotrope based on the concatenation of phenyl- and naphthyl-like blocks through tetragonal rings. This system is a narrow-gap semiconductor, which is also suitable to be cast into a boron-nitride configuration since it is a bipartite structure featuring only even-membered rings. It turns out BN configurations of naphthylene-γ can potentially result in systems suitable to be embedded into nanoelectronics applications, since they are expected to exhibit robust band gaps. With this motivation, we investigate the electronic properties of several hybrid systems hypothetically obtained by replacing part of naphthylene-γ’s C atoms by BN sectors with different concentrations. Our first principles simulations are based on density functional theory and show that the energy gap for these systems does not vary monotonically with increasing BN concentration. In fact, strategical choices for the sites undergoing C-to-BN substitution result in specific modifications in the electronic signature of the systems. We also investigated full-BN naphthylene-γ sheets which show band gaps significantly different from those of hexagonal-BN. We further investigated nanoribbons based on these BN sheets, showing that they closely follow the properties of their parent 2D structure, as they feature frontier states internally located over the ribbon structures. [Display omitted] •Hybrid 2D carbon allotrope.•First-principles calculations.•DFT.•BCN structures with large pores.•Naphthylene-γ.