Electronic Transport of the Adsorbed Trigonal Graphene Flake: A First Principles Calculation

Based on the non-equilibrium Green's function method combined with the density functional theory, we investigate the transport properties of a zigzag trigonal graphene flake (zTGF) adsorbed by a single atom (F or H) or a single group (OH or CH₃) at the central site and connected to two symmetric Au electrodes by Au–S bonds. The results show that the OH adsorption can enhance the conductance, followed by the negative differential resistance effects, while the conductance for the zTGF adsorbed by H and CH₃ is lowered obviously, and rectifying characteristics can be observed for the H-adsorbed system. The adsorbing action alters the molecular level position and the spatial distribution of the molecular orbital, leading to different transport properties.