A Molecular Switch Based on Potential-Induced Changes of Oxidation State

by Fan Chen et al. Nano Letters, 18 Feb 2005 (Web release) We have measured the conductance of a hepta-aniline oligomer attached to gold electrodes held under potential control in electrolyte. It increases fifteen-fold on oxidation from the leucoemeraldine form to the emeraldine salt. The single-molecule current-voltage characteristic, linear in toluene, displays negative differential resistance in an acidic electrolyte. The negative differential resistance is accounted for by modification of the local surface potential by the applied bias. These results connect electrochemical data directly to molecular electronic behavior in a two-terminal device. Read the article