Self-assembled nanogaps for molecular electronics

Abstract

A nanogap for molecular devices was realized using solution-based self-assembly.Gold nanorods were assembled to gold nanoparticle-coated conductingSnO2:Sb nanowires via thiol end-capped oligo(phenylenevinylene)s (OPVs). The molecular gap waseasily created by the rigid molecule itself during self-assembly and the gap length wasdetermined by the molecule length. The gold nanorods and gold nanoparticles, respectivelycovalently bonded at the two ends of the molecule, had very small dimensions, e.g. a width of∼20 nm, and hence were expected to minimize the screening effect. The ultra-long conductingSnO2:Sb nanowires provided the bridge to connect one of the electrodes of the molecular device(gold nanoparticle) to the external circuit. The tip of the atomic force microscope(AFM) was contacted onto the other electrode (gold nanorod) for the electricalmeasurement of the OPV device. The conductance measurement confirmed that theself-assembly of the molecules and the subsequent self-assembly of the gold nanorods wasa feasible method for the fabrication of the nanogap of the molecular devices.