Tuning the band gap in graphene nanoflakes via various impurities

Abstract

The electronic properties of GNFs are controlled by utilizing different impurities, such as boron, nitrogen and oxygen. The differences in the electronic properties of the pristine GNFs with and without various concentrations of B, N and O impurities in different sites are calculated by utilizing the DFT method. The results show that the pristine GNFs has insulator behavior. By using a single B, N or O impurity, the electronic band gap is reduced and the behavior is changed from insulator to semiconductor behavior. Our findings show that the electronic properties of single (B, N or O)-doped GNFs depended on these impurities and the location of the impurities. By increasing the concentrations of these impurities, the GNFs still have semiconductor behavior, but the electronic band gap is increased by increasing the number of C atoms between these impurities. These are very interesting results: the electronic properties depend on the number of C atoms between these impurities. The Fermi level is shifted up with all these impurities, except B2 case (c), B2 cases (a and b) and B4 cases (b and c) doped GNFs, which have the opposite behavior. These impurities make the GNFs more stable and less reactive due to the total energy being increased by the increasing the number of impurities and changing the sites of these impurities inside the GNFs, although the opposite happens for B cases (b and c), B2 cases (a, b, and d), and B4 (all cases) doped GNFs. In brief, the electronic properties depended on the concentrations and the sites of these impurities, which can be utilized in various applications.