Surface characterization (XPS and SIMS) of emersed polybithiophene electrodes

Emersed polybithiophene (pbT) films, doped at different levels with ClO₄⁻, have been prepared by both discharging fully charged samples and charging fully discharged samples. The different strengths of two surface techniques, e.g. x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS), have been fully exploited in the analysis of emersed pbT samples. XPS has been used to assess the relative atomic concentrations of species from substratum, dopant and, for the first time, solvent (acetonitrile). Curve analysis has been employed, where necessary, to discern between different chemical environments of the same atom. Different chemical environments for acetonitrile molecules have been observed in different samples. The higher surface sensitivity of static SIMS and variable-angle XPS has been employed to distinguish between double layer and more deeply located mobile species. The participation of all mobile species (anions, cations and solvent molecules) to the charging-discharging process and the direction of migration of them at the different stages of the process have been assessed and found to be in good agreement with previous reports.