Synthesis and characterization of an electrochromic copolymer based on 2,2′:5′,2″-terthiophene and 3,4-ethylenedioxythiophene

A new electrochromic copolymer of 2,2′:5′,2″-terthiophene (TT) with 3,4-ethylenedioxythiophene (EDOT) was synthesized in 0.1 M tetrabutylammonium perchlorate as supporting electrolyte and characterizations of the resulting copolymer P(TT-co-EDOT) performed by cyclic voltammetry, UV–vis spectroscopy, scanning electron microscopy, fourier transform infrared spectroscopy, nuclear magnetic resonance and thermal analysis. Spectroelectrochemical investigations showed that the copolymer film has electrochromic properties. It showed five different colors at various potentials (sky blue, gray, light purple, blues violet and dark blues violet). Double potential step chronoamperometry experiment illustrated that copolymer film had good stability, fast switching time and high optical contrast. At the neutral state of the copolymer λmax was found at 500 nm and Eg was calculated as 1.63 eV. The copolymer film showed a maximum optical contrast of 54% at 1,100 nm with a short response time.