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. (C) 2001 Elsevier Science B.V. All rights reserved.