Electrochemical synthesis and investigation of poly(1,4-bis(2-(3,4-ethylenedioxy)thienyl)benzene) and its application in an electrochromic device

Abstract

1,4-Bis(2-(3,4-ethylenedioxy)thienyl)benzene, prepared by Stille cross-coupling reaction was successfully electrochemically polymerized to give polymer 1,4-bis(2-(3,4-ethylenedioxy)thienyl)benzene (PEBE). Characterizations of the resulting polymer PEBE were performed by cyclic voltammetry (CV), UV–vis, Fourier transform infrared spectroscopy and scanning electron microscopy. Moreover, the spectroelectrochemical and electrochromic properties of the polymer film were investigated. The resulting polymer film has distinct electrochromic properties and shows three different colors (deep red, gray, and light blue) under various potentials. At the dedoped state of the polymer, the π–π* transition absorption peak is located at 510 nm and the optical band gap (E g) was calculated as 1.92 eV. The PEBE film shows a maximum optical contrast (ΔT%) of 31.0 % at 500 nm with a response time of 0.85 s. The coloration efficiency of PEBE film was calculated to be 182.2 cm2C−1. An electrochromic device (ECD) based on PEBE and poly(3,4-ethylenedioxythiophene) was also constructed and characterized. The response time was measured as 0.4 s, and the coloration efficiency of the device was calculated to be 225.4 cm2C−1. Furthermore, this ECD exhibited satisfactory optical memories and redox stability.