Structural, electronic and transport properties of a single 1,4-benzenediamine molecule attached to metal contacts of Au, Ag and Cu

Abstract

We investigated molecular junctions formed by a single 1,4-benzenediamine molecule bridging between Au, Ag or Cu electrodes. We show that the molecule interacts stronger with Cu than both Ag and Au, which is in good agreement with the atomic overlap population analysis. The DFT-computed transmission characteristics of junctions described are dominated by tunnelling effects through the highest-occupied molecular orbital (HOMO). Our results also reveal that junctions formed with Au electrodes are more conductive than those formed with Ag and Cu electrodes, consistent with the lower work functions for Ag and Cu. By analyzing the calculated I × V curves for the Au, Ag, Cu/BDAH /Cu, Ag, Au 4 junctions we verify an ohmic behavior. In addition, a weak rectifying performance is verified, for all junctions. Our results thus reinforce the fact that the nature of the metal-molecule interaction and the choice of the electrode materials are important factors for modulating the transport properties of single-molecule junctions.