Electrochemical investigation of thin PEDOT film above an insulating substrate using scanning electrochemical microscopy

Thin layer of conducting polymer, poly(3,4-ethylenedioxythiophene) PEDOT, deposited on insulating substrates was electrochemically investigated. This study was performed through the reaction with a series of electrogenerated mediators at a microelectrode operating in the configuration of a scanning electrochemical microscope (SECM). The method proves to be a convenient tool for investigating redox properties of the electroactive materials onto insulating substrate and the occurrence of electron transfers across the modified substrate. The SECM results demonstrate the possibility of the regeneration of the mediator at the modified surface even if the used substrate is an insulator. The regeneration rate depends on the standard redox potential of the mediator, on the switching potential of the polymer and on its initial oxidation state. In addition, the obtained data could be analyzed through the construction of the steady state voltammograms allowing the extraction of the electrochemical properties of the thin organic layer deposited onto insulating surface.