A KELVIN PROBE FORCE MICROSCOPIC STUDY OF THE LOCAL DOPANT DISTRIBUTION IN CONDUCTING POLYBITHIOPHENE

Local dopant distribution in electrochemically deposited polybithiophe ne films as well as the effect of the electrochemical treatment were s tudied ex situ using the-technique of Kelvin probe force microscopy (K FM). The doping-level distribution was found to be directly related to the polymer surface morphology. For the as-grown polymer, most of the doping anodic charge was found to be located at the grain tops. The p olymer that was further electrochemically doped featured relatively hi gher doped grain periphery and less doped grain tops. On the contrary, undoping of the polymer resulted in no pronounced change in the dopan t distribution pattern. The effect of the pretreatment of the HOPG sup port on the properties of the polymer films is also discussed. A model is proposed that relates the observed inhomogeneity to the lateral di stribution of the primary polymer nuclei formed during the initial ste ps of the polymer deposition process. The results suggest that the KFM is a powerful tool for studying dopant distribution in conducting pol ymers. (C) 1997 Published by Elsevier Science Ltd.