Electronic transport property of 4,4′-bipyridine molecular junction

The electronic transport properties of a single 4,4′-bipyridine molecule sandwiched between two gold electrodes are studied by using first-principles non-equilibrium Green's function method. The theoretical results show that the relative position of the lowest unoccupied molecular orbital lies close to the Fermi level, and shifts away by applying voltage bias. The transmission of the molecular junction is almost contributed by a single conductance channel at small bias. The conductance behavior of the 4,4′-bipyridine junction is metallic. The current does not change significantly by varying the distance of Au-N slightly and is found to be linear at small bias. Theoretical results reproduce the main features of the experimental current-voltage characteristics.