Application of in situ UV-vis spectroscopy and an in situ dc resistance measurement technique to the study of a poly(thiophene-3-methanol) film

Abstract

The evolution of the UV-vis optical absorption of poly(thiophene-3-methanol) (PTM) has been followed as a function of applied potential in Bu4NClO4 and Bu4NPF6 in acetonitrile. The UV-vis spectra at 310 to 820 nm show similar features to many polythiophenes of higher degrees of conjugation. The behaviour of the absorbance maxima corresponding to interband transition and (bi)polaron bands have also been registered during linear sweeps and potential step measurements in order to characterize the response of the PTM to applied potential, and the recovery of the polymer film during reduction. The evolution of the absorbance shows differences in the behaviour of the films synthesized and studied in the presence of the two anions. These correlate with our previous in situ FTIR measurements. The study of a conductive polymer by the newly developed contact electric resistance (CER) technique is reported for the first time. This in situ dc resistance measurement technique has been applied for determining the behaviour of the resistance of PTM during linear sweep measurements as well as for estimation of the maximum conductivity of the PTM, which was about 10−4 S/cm. The results obtained by UV-vis spectroscopy and CER technique are compared.