Tuning of the Band Structures of Zigzag Graphene Nanoribbons by an Electric Field and Adsorption of Pyridine and BF3: A DFT Study

The influence of pyridine adsorption and the applied electric field on the band structure and metallicity of zigzag graphene nanoribbons (ZGNRs) was investigated by using density functional theory (DFT) calculations. The semiconducting ZGNRs became half-metallic or remained semiconducting depending on the configuration of N-C covalent bonds between pyridine and the outermost C atom of the ZGNRs. In addition, the band gap of the alpha- and beta-spin states of the ZGNRs could be tuned by noncovalent bonds. This effect was enhanced when BF3 was introduced simultaneously at the opposite edge. The applied external electric field also modulated the band structures of the ZGNRs, making them half-metallic or semiconducting to some extent. These features suggest that the well-arranged adsorption of pyridine and BF3 could be used to tune the band structures of nanoscale electronic devices based on graphene.