Electronic Properties of α-graphyne Nanoribbon with Vacancies

This research applies Density Functional Theory (DFT) to investigate the density of states (DOSs) and band structure and of alpha-graphyne nanoribbon (alpha-GYNRs) with 1 x 3 x 3 supercells. For this purpose, the GGA-PBE approximation and Non-equilibrium Green's Function (NEGF) approach are employed. A single carbon atom is removed to simulate the vacancy defect on the nanoribbon. According to the results, unlike alpha-graphene nanosheet, which has a band gap of 0 eV and is a semimetal, pure alpha-GYNRs has a band gap of 0.49 eV and is a semiconductor. Removing a carbon atom at 7 different points of alpha-GYNRs and creating a vacancy lowers the band gap significantly. The band gap in some structures is close to zero, which can be considered pseudo-metals. In addition, the DOS plots show that the height and number of peaks at energies 0 to -5 eV are higher than at energies 0 to +5 eV. Furthermore, the band gap due to the created vacancy directly depends on the vacancy position of the nanoribbon. Hence, the single-atom vacancy (SAV) defect in the alpha-graphyne nanostructure can lead to a subsurface structural rearrangement. Accordingly, it can be an important parameter in tuning the electronic characteristics of alpha-GYNRs structures.