title: When electron transfer meets electron transport in redox-active molecular nanojunctions.
abstract: A scanning electrochemical microscope (SECM) was used to arrange two microelectrodes face-to-face separated by a micrometric gap. Polyaniline (PANI) was deposited electrochemically from the SECM tip side until it bridged the two electrodes. The junctions obtained were characterized by following the current through the PANI as a function of its electrochemical potential measured versus a reference electrode acting as a gate electrode in a solid-state transistor. PANI nanojunctions showed conductances below 100 nS in the oxidized state, indicating control of the charge transport within the whole micrometric gap by a limited number of PANI wires. The SECM configuration makes it possible to observe in the same experiment and in the same current range the electron-transfer and electron-transport processes. These two phenomena are distinguished here and characterized by following the variation of the current with the bias voltage and the scan rate. The electron-transfer current changes with the scan rate, while the charge-transport current varies with the bias voltage. Finally, despite the initially micrometric gap, a junction where the conductance is controlled by a single oligoaniline strand is achieved.
authors: NanoElectroChemistry Group, Université Paris Diderot, ITODYS, UMR 7086 CNRS, 75205 Paris Cedex 13, France.
authors: Marion
authors: M
authors: Janin
authors: Jalal
authors: J
authors: Ghilane
authors: Jean-Christophe
authors: JC
authors: Lacroix
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D004579:Electron Transport; D004583:Electrons; D008839:Microelectrodes; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction
chemical_list: D000814:Aniline Compounds; C416807:polyaniline