Synthesis of π-Conjugated Polymer Thin Films by Electropolymerization of Benzodithiophene Derivatives

pi-conjugated polymer thin films are successfully prepared by the electropolymerization of 4,5-diaryl benzodithiophenes, which are readily obtained by the three-component coupling reactions of aryl iodides, 1,2-di(thiophen-2-yl) ethyne, and phenylboronic acid, followed by the photochemical annulation. The resulting polymer films exhibit pi-conjugated properties as convinced from their UV-vis absorption spectra and cyclic voltammetric analyses. The electronic properties such as highest occupied molecular orbital (HOMO) energy levels of the resulting polymer films are affected by the 4-aryl substituents. The pi-conjugated polymer thin films exhibit electrochromism, where the color of the polymer film turns from yellow to blue by oxidation.