Electrical conductance of single-molecular junctions formed with palladium electrodes

We measured the conductance of a series of amine-terminated oligophenyl molecular junctions formed with palladium (Pd) electrodes by using a scanning tunneling microscope-based break-junction technique. For comparison, we also used Au electrodes to form a metal-molecular junction. We found that the molecular junctions formed with Pd electrodes had higher conductances than those formed with gold (Au) electrodes through a statistical analysis and a conductance histogram. Furthermore, the measured conductance decayed exponentially with molecular backbone length with a tunneling decay constant that was essentially the same for Pd and Au electrodes, which is attributable to the molecules that conduct through the highest occupied molecular orbital and the higher work function of Pd compared with Au. Because our work allows measuring the conductance of a molecule formed with various metal electrodes to be measured, it should be relevant to molecular junctions with various materials for future organic electronics on a molecular scale.