Charge Transport in Conducting Polymer
G. INZELT, Charge Transport in Conducting Polymer Film Electrodes, Chem. Biochem. Eng. Q. 21 (1) 1–14 (2007)
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Charge Transport in Conducting Polymer Film Electrodes
G. Inzelt Eötvös Loránd University, Institute of Chemistry, Budapest, Pázmány Péter sétány 1/A, H-1117, Hungary E-mail: inzeltgy@chem.elte.hu
Review Received: August 4, 2006 Accepted: December 13, 2006
The essential features of charge transport in conducting polymer film electrodes are discussed. Selected experimental results are presented, which shed light on the complex nature of the processes occurring in these systems. The problems of the theoretical elucidation and practical consequences are also emphasized. Key words: Conducting polymers, charge transport, film morphology, relaxation
Introduction
The elucidation of the nature of charge transfer and charge transport processes in electrochemically active polymer films may be the most interesting theoretical problem of the field. It is also a question of great practical importance, because in the majority of their applications fast charge propagation through the film is needed.1–14 A polymer film electrode can be defined as an electrochemical system in which at least three phases are contacted successively in such a way that between a first-order conductor (usually a metal) and a second-order conductor (usually an electrolyte solution) is an electrochemically active polymer layer. The polymer layer is more or less stably attached to the metal, mainly by adsorption (adhesion). The fundamental observation that should be explained is that even rather thick polymer films in which most of the redox sites are as far from the metal surface as 100 – 10 000 nm may be electrochemically oxidized or reduced. According to the classical theory of simple electron-transfer reactions, the reactants get very close to the electrode surface, and then electrons can tunnel over the short distance (some nanometers) between the metal and the activated
1
Charge Transport in Conducting Polymer Film Electrodes
G. Inzelt Eötvös Loránd University, Institute of Chemistry, Budapest, Pázmány Péter sétány 1/A, H-1117, Hungary E-mail: inzeltgy@chem.elte.hu
Review Received: August 4, 2006 Accepted: December 13, 2006
The essential features of charge transport in conducting polymer film electrodes are discussed. Selected experimental results are presented, which shed light on the complex nature of the processes occurring in these systems. The problems of the theoretical elucidation and practical consequences are also emphasized. Key words: Conducting polymers, charge transport, film morphology, relaxation
Introduction
The elucidation of the nature of charge transfer and charge transport processes in electrochemically active polymer films may be the most interesting theoretical problem of the field. It is also a question of great practical importance, because in the majority of their applications fast charge propagation through the film is needed.1–14 A polymer film electrode can be defined as an electrochemical system in which at least three phases are contacted successively in such a way that between a first-order conductor (usually a metal) and a second-order conductor (usually an electrolyte solution) is an electrochemically active polymer layer. The polymer layer is more or less stably attached to the metal, mainly by adsorption (adhesion). The fundamental observation that should be explained is that even rather thick polymer films in which most of the redox sites are as far from the metal surface as 100 – 10 000 nm may be electrochemically oxidized or reduced. According to the classical theory of simple electron-transfer reactions, the reactants get very close to the electrode surface, and then electrons can tunnel over the short distance (some nanometers) between the metal and the activated
References: G. INZELT, Charge Transport in Conducting Polymer Film Electrodes, Chem. Biochem. Eng. Q. 21 (1) 1–14 (2007) 13