Negative differential resistance induced by intermolecular interaction in a bimolecular device

Using nonequilibrium Green's functions in combination with the density-functional theory, we study the electronic transport properties of the molecular device constructed by two cofacial oligo(phenylene ethynylene) molecules and gold electrodes. The results show that negative differential resistance can be observed when the intermolecular distance closes to a certain value. We propose that a combination of the splitting of the molecular orbitals due to the intermolecular interaction and the change of the coupling between the molecules and the electrodes at different biases might be responsible for the negative differential resistance behavior. (c) 2007 American Institute of Physics.