Optical, conductive and magnetic properties of electrochemically prepared alkylated poly(3,4-ethylenedioxythiophene)s

Several alkylated 3,4-ethylenedioxythiophene (EDT-CnH2n+1; n=1,6,10,14) derivatives were electrochemically polymerized in acetonitrile, after which the corresponding polymers were characterized and their properties were studied (cyclic voltammetry, UV–VIS, in situ conductivity and in situ ESR). With increasing alkyl chain length (i) the electronic spectra show an increased coplanar disposition of the thiophene rings; (ii) the conductivity initially decreases and then increases again, and (iii) injected polarons are dimerized to the same level, independently of the alkyl chain length. An exceptionally high conductivity (850 S/cm) is found for the tetradecyl-substituted polymer.