Investigation of the applied potential limits for polypyrrole when employed as the active components of a two-electrode device

The long-term operation of two-electrode all polymer devices requires a bal ance between extending the potential limits as far as possible to give full oxidation and reduction of the conducting electroactive polymers (CEPs), w hile ensuring that the potentials at which overoxidation occurs are not rea ched. In this work, the "true" potential (versus Ag/AgCl) at one electrode in a two-electrode cell was determined whilst applying a range of potential differences between the two polypyrrole (PPy) electrodes. At an applied po tential of +/-2 V, only slight overoxidation of PPy was evident at either e lectrode. However, for long-term applications of polymer films, it was show n that 11.5 V would be more suitable. This potential difference was applied over an extended period in a series of potential steps to a two-electrode device in a propylene carbonate (PC) solution and found to have no deleteri ous effects on the polymer electrodes. It was also shown that this potentia l difference was sufficient to fully oxidise and reduce PPy both in a suppo rting electrolyte solution and as a component of a two-electrode solid stat e device. (C) 2001 Elsevier Science B.V. All rights reserved.