Electrochromic properties of a novel low band gap conductive copolymer

Yigitsoy B., Varis S., Tanyeli C., Akhmedov I. M., Toppare L.

ELECTROCHIMICA ACTA, vol.52, no.23, pp.6561-6568, 2007 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 52 Issue: 23
  • Publication Date: 2007
  • Doi Number: 10.1016/j.electacta.2007.04.083
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.6561-6568
  • Keywords: electrochemical polymerization, conducting copolymers, electrochromic devices, THIOPHENE, ELECTROCHEMISTRY, ELECTRODES, POLYMERS
  • Middle East Technical University Affiliated: Yes


A copolymer of 2,5-di(thiophen-2-yl)-1-p-tolyl-1H-pyrrole (DTTP) with 3,4-ethylene dioxythiophene (EDOT) was electrochemically synthesized. The resultant copolymer P(DTTP-co-EDOT) was characterized via cyclic voltammetry, FTIR, SEM, conductivity measurements and spectroelectrochemistry. Copolymer film has distinct electrochromic proper-ties. It has four different colors (chestnut, khaki, camouflage green, and blue). At the neutral state; gimel(max) due to the pi-pi* transition was found to be 487 nm and E-g was calculated as 1.65 eV. Double potential step chronoamperometry experiment shows that copolymer film has good stability, fast switching time (less than 1 s) and good optical contrast (20%). An electrochromic device based on P(DTTP-co-EDOT) and poly(3,4-ethylenedioxythiophene) (PEDOT) was constructed and characterized. The device showed reddish brown color at -0.6 V when the P(DTTP-co-EDOT) layer was in its reduced state; whereas blue color at 2.0 V when PEDOT was in its reduced state and P(DTTP-co-EDOT) layer was in its oxidized state. At 0.2 V intermediate green state was observed. Maximum contrast (%Delta T ) and switching time of the device were measured as 18% and 1 s at 615 nm. ECD has good environmental and redox stability. (c) 2007 Elsevier Ltd. All rights reserved.