ABSTRACT
The transition from the semiconducting state to the metallic state-the SM transition-of conjugated polymers (CPs) under conditions of increasing doping is a perennial problem, part of the history of the research area of conjugated polymers. It is still perplexing that the semiconducting state of disordered polymers, now dominantly described as a state where hopping of charges between localized states occurs, to the metallic state of highly doped polymers, with increasing disorder, could at all be obtained in the same material. It would be even more surprising if this could be described in a single intellectual framework. The electrochemical functions of conjugated polymers rely on electronic charge transport and ionic charge transport-redox processes with all the concomitant processes due to co-transport of solvent, expansion/contraction of polymer chains, change of polarizability and surface energy, and first and foremost, change of electronic and ionic transport parameters. The change of electronic structure, electronic transport properties and
2.1 Intellectual Transitions in the Study of CP Electrochemistry ........................30 2.2 Electronic Transport at Different Doping Levels ...........................................30 2.3 The Moving Front ........................................................................................... 32 2.4 Lateral Electrochemistry in Devices ..............................................................34 2.5 Modeling of the SM Transformation Including Electrochemical
Elements.......................................................................................................... 35 2.6 Unification of Electronics and Electrochemistry ...........................................36 2.7 Conclusion ...................................................................................................... 38 2.8 Acknowledgments ........................................................................................... 38 References ................................................................................................................ 38
optical properties, ion transport conditions, and structural reorganization lead to a completely different material. The research traditions addressing the semiconductormetal transition in highly doped CPs has many strands, and this account will be a rather personal and possibly eccentric selection of topics. A common theme is the use of electrochemical methods and concepts to advance the understanding of the SM transition. A desire is that of unifying the different modes of understanding electronic and ionic transport in solid-state electronics and in the electrochemistry of conjugated polymers.
