Solubility controlled electropolymerisation and study of the impact of regioregularity on the spectroelectrochemical properties of thin films of poly(3-octylthiophenes)

Electrochemical polymerisation of 3-octylthiophene and 4,4′-dioctyl-2,2′-bithiophene in acetonitrile is reported. The nature of the resultant films was investigated through electrochemical and spectroelectrochemical means, in concert with quantum mechanical calculations to evidence the oligomeric nature of the deposits. Control of conjugation length through solubility modification is demonstrated through investigation of UV–vis spectra of polymers prepared in different solvents. ESR–UV–vis–NIR spectroelectrochemical measurements were used to gauge the differences in the behaviour of regioregular and regiorandom deposits. Conjugation length was found to vary significantly between the two polymers. This is shown to influence the nature of charge carriers generated upon p-doping of the system.