Electrochromic Properties of Copolymer of Terephthalic Acid Bis‐(thiophen‐3‐yl‐methyl) Thioester with Pyrrole

Terephthalic acid bis‐(thiophen‐3‐yl‐methyl) thioester (TTMT) was synthesized via the reaction of thiophen‐3‐yl methanethiol with terephthaloyl dichloride. This 3‐functionalized thiophene monomer was polymerized in the presence of pyrrole (Py) upon constant potential application. Spectroelectrochemistry experiments reflected a π to π∗ transition with a band gap energy of 2.4 eV for the copolymer. A dual type electrochromic device (ECD) of P(TTMT‐co‐Py) and poly(3,4‐ethylenedioxythiophene) (PEDOT) was constructed. The device switches between greenish yellow and blue upon application of −2.4 V and +0.8 V, respectively. Optical contrast was calculated as 17.5%, whereas switching time was found as 1.6 s at maximum contrast point.