The influence of the structural defects and microscopic aggregation of poly(3-alkylthiophenes) on electrochemical and optical properties of the polymer films: discussion of an origin of redox peaks in the cyclic voltammograms

A comparative analysis of electrochemical and optical behaviour has been carried out on poly(3-hexylthiophene) and poly(3-dodecylthiophene) films of different content of HT couplings. The spectroelectrochemical properties of these polymers were examined by means of cyclic voltammetry (CV), differential cyclic voltabsorptometry (DCVA) and UV/vis spectroscopy at various doping levels. The presence of two or three redox peaks in the cyclic voltammograms, as well as the peak and shoulders in absorbance spectra of the neutral polymers, was discussed in terms of the co-existence of different types of zones with various morphology, crystallinity and conjugation lengths. The possibility of formation of a interchain bonds between the chains of the polymer studied is questioned, taking into account the results of DCVA and voltammetric measurements at different scan rates in the range 10-100 mV/s. (C) 2001 Elsevier Science Ltd. All rights reserved.