Electrical Switching in π-Resonant 1D Intermolecular Channels

We studied the influence of π-orbital coupling in a 1D stack of 4,4′-biphenyldithiol (BDT) on the resulting electronic and electrical properties of the assembly. The conduction and the field-switching properties of the BDT assembly are compared as the intermolecular distances are reduced to below 4 Å. The system in the regime of strong π-interactions shows large conductance modulations upon application of a transverse gate field. The switching mechanism involves a delocalized π-resonance, i.e., resonant tunneling in the intermolecular π- and π*-bands of the BDT assembly. The transmission is found to be significantly higher in the π*-resonance. This behavior is discussed in terms of the density of states distribution in the conducting states.