Direct pyrolysis mass spectrometry analysis of fresh and aged PF6--doped polythiophenes

In this study, pyrolysis mass spectrometry has been applied for the investigation of thermal characteristics of PF6--doped polythiophene (PTh) films. Thermal degradation of PTh showed behaviour identical with BF4--doped polythiophene (BF4--PTh), indicating that the effects of the dopants in question on the thermal characteristics of the PTh are not significant. Besides the oligomer peaks (up to hexamer), peaks indicating decomposition of the thiophene ring have also been detected as in the case of BF4--PTh. However, the data also indicated that the oxidation of the PF6- dopant was much more effective, yielding mainly POF3, H3PO4 compounds even for the freshly prepared samples. Upon ageing, the yield of these products increased and exposure to air for more than 50 days also caused degradation, of the PTh chains. Furthermore, substitution of the thiophene (Th) ring by fluorine has been recorded and was associated with reactions of Th with the reactive oxidation products of the dopant. Analyses of the de-doped samples showed that although de-doping was effective to a certain extent, inward diffusion of the counter ion (C4H9)(4)N+ has also occurred. This diffusion was more efficient than that was observed for BF4-PTh samples