SURFACE MORPHOLOGY CHANGES IN POLYTHIOPHENE AND POLYTHIOPHENE DERIVATIVE FILMS AFTER BEING OXIDIZED WITH IODINE - A SCANNING PROBE MICROSCOPY STUDY

摘要

The nanometer-scale surface morphology of polythiophene (PT) and polythiophene derivative thin films was found to change substantially after exposure to I-2 vapor. Small PT bundles with an average dimension of 400 Angstrom were observed in films prior to oxidation (doping) by I-2, using the technique of scanning probe microscopy. However, upon doping by I-2, the bundles in the same film were replaced by much larger units with a range of different sizes. The oxidation process was instantaneous, and ail the derivative films behaved in a qualitatively identical fashion. The change in morphology is concluded to be due to aggregation of the polymer chains, which is caused by charge species introduced through oxidation by I-2. [References: 18]