Asymmetric electron transport through a conjugated–saturated hydrocarbon molecular wire

To understand the barrier effect on the asymmetric electron transport, we have employed a series of hybrid molecular junctions composed of conjugated and saturated hydrocarbon chains. The length of molecular wire is fixed, while the ratio of conjugated and saturated chains varies. In each model, the current–voltage characteristics have been studied using the first-principles density functional theory in conjunction with the non-equilibrium Green’s function method. We found that the rectification performance is correlated to the barrier length. The mechanism of this phenomenon is related to the asymmetric coupling between the conjugated moiety and the metallic electrode.