A new soluble conducting polymer and its electrochromic devices

Abstract

A new polythiophene derivative was synthesized by both chemical and electrochemical oxidative polymerization of 1-(1-phenylethyl)-2,5-di(2-thienyl)-1H-pyrrole (PETPy). Of which the chemical method produces a polymer that is completely soluble in organic solvents. The structures of both the monomer and the soluble polymer were elucidated by nuclear magnetic resonance (H-1 and C-13 NMR) and Fourier transform infrared (FTIR) spectroscopy. The average molecular weight has been determined by gel permeation chromatography to be M-n = 3.29 x 10(3) for the chemically synthesized polymer. Polymer of PETPy was synthesized via potentiostatic electrochemical polymerization in acetonitrile (AN)/NaClO4/LiClO4 (0.1 M) solvent-electrolyte couple. Characterizations of the resulting polymer were performed by cyclic voltammetry, FTIR, scanning electron microscopy, and UV-vis spectroscopy. Four-probe technique was used to measure the conductivities of the samples. Moreover, the spectroelectrochemical and electrochromic properties of the polymer films were investigated. In addition, dual-type polymer electrochromic devices based on P(PETP,) with poly(3,4-ethylenedioxythiophene) were constructed. Spectroelectrochemistry, electrochromic switching, and open circuit stability of the devices were studied. They were found to have good switching times, reasonable contrasts, and optical memories.