Novel ferrocene derivatized poly(2,5-dithienylpyrrole)s: Optoelectronic properties, electrochemical copolymerization

In this study a novel ferrocene-substituted electrochromic polymer, poly(4-(2,5-di-thiophen-2-yl-pyrrol-yl)-N-(ferrocenyl methyl)-phenylamine), poly(SNS-An-Fc), was electrochemically synthesized and its electrochromic properties were investigated in detail. The cyclic voltammogram of SNS-An-Fc involves a reversible Fe-II/III wave and an irreversible SNS based oxidation wave at higher potentials. Contrary to some of the previous thiophene based systems, the homopolymer was successfully synthesized and the redox activity of the homopolymer film virtually did not change upon repeated cycling between 0.0 and 1.1 V while showing the characteristic of a surface-confined redox couple. The homopolymer has a band gap of 2.02 eV and it displays yellow to blue coloration upon doping. Copolymerization, which is known as an effective method to tune the electrochromic properties of the material, was also realized in the presence of 3,4-ethylenedioxythiophene (EDOT). The copolymer revealed multichromic behavior displaying four different colors. Our studies have shown that SNS-An-Fc based polymers are promising candidates for electrochromic applications. (C) 2011 Elsevier Ltd. All rights reserved.