Electrochromic properties of a soluble conducting polymer of 1-benzyl-2,5-di(thiophene-2-yl)-1H-pyrrole

In this study, synthesis of a thiophene functionalized monomer, 1-benzyl-2,5-di(thiophene-2-yl)-1H-pyrrole (SNBS) was achieved. A new polythiophene derivative was synthesized by both chemical and electrochemical polymerization. The polymer synthesized via chemical oxidative method was soluble in organic solvents and characterized by nuclear magnetic resonance (H-1 and C-13 NMR) spectroscopy. The average molecular weight of the chemically synthesized polymer was determined by gel permeation chromatography (GPC) as Mn = 8.0 x 10(3) The electrochemical oxidative polymerization of SNBS was performed via potentiodynamic method using NaClO4/LiClO4 as the supporting electrolyte in acetonitrile (AN). Characterizations of the resulting polymer were performed by cyclic voltammetry (CV), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and UV-vis spectroscopy. Electrical conductivity of P(SNBS) was measured by the four-probe technique. Spectroelectrochemical analysis presents that the polymer has an electronic bandgap, of 1.9 eV, with a light gray color in the fully reduced form and a dark gray color in the fully oxidized form. The switching ability of P(SNBS) was monitored and the percent transmittance (%T) was found as 12%. Dual-type complementary colored electrochromic device (ECD) using P(SNBS)/poly(3,4-ethylenedioxythiophene) (PEDOT) in sandwich configuration were constructed. Spectroelectrochemistry, switching ability and optical memory of the electrochromic devices were investigated. (c) 2006 Elsevier B.V. All rights reserved.