Evolutions of structure of a thin polybithiophene film upon doping and cycling studied by in situ SERS technique

Raman spectra of a thin polybithiophene (PBth) film deposited onto a stainless-steel electrode have been consecutively recorded during electrochemical oxido-reduction cycles in boron fluoride—ethyl ether. It is shown that the PBth spectra displayed a noticeable SERS effect on the stainless-steel surface, providing a significant disparity in the vibration modes between the spectra of the reduced and the oxidized forms; some bands were strongly enhanced in SERS spectra of the oxidized species due to its resonance with laser line wave. Furthermore, the changes occurring during the doping—dedoping process, such as orientation of PBth rings on metal, defects in the polymeric chains, charge transport and solvent intrusion, etc., can be obtained.