Electrosynthesis and characterizations of a multielectrochromic copolymer based on pyrrole and 3,4‐ethylenedioxythiophene

A copolymer based on pyrrole and 3,4‐ethylenedioxythiophene (EDOT) was electrochemically synthesized on an indium tin oxide ITO/glass electrode in acetonitrile containing lithium perchlorate (LiClO₄). The resultant copolymer is characterized via cyclic voltammetry, FTIR, SEM, XPS, and spectroelectrochemical analysis. The spectroelectrochemical analysis revealed the copolymer film has distinct electrochromic properties with respect to the homopolymers, and presented four colors (amaranth, brick red, dark grey, and light blue) under various applied potentials. For the copolymer in the neutral state, the calculated onset energy for the π–π* transition (E_g) is 1.69 eV, and the absorption peak (λ_max) is located at 508 nm. The maximum transmittance contrast (ΔT%) is 39.2% at 946 nm between the fully oxidized and intermediate(?0.4 V) states. Successive cyclic voltammograms and electrochromic switching experiment indicate the good stability of the copolymer because of the incorporation of EDOT units into the polypyrrole. It retains 81% of the original electroactivity and 71.8% of contrast after 2000 cycles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013