Electrochemical Synthesis and Characterization of a New Electrochromic Copolymer Based on 2,2′-Bithiophene and Tris[4-(2-Thienyl)phenyl]amine

A novel copolymer based on tris[4-(2-thienyl)phenyl]amine (TTPA) and 2,2′-bithiophene (BT) was electrochemically synthesized. Characterizations of the resulting copolymer P(TTPA-co-BT) were performed by cyclic voltammetry (CV), UV–vis spectroscopy, Fourier transform infrared spectroscopy(FT-IR), scanning electron microscopy (SEM). The P(TTPA-co-BT) film had distinct electrochromic properties from both the PTTPA and the PBT homopolymers, and exhibited three different colors (claybank, grass green, and blue) under various potentials. Moreover, the copolymer film showed high optical contrasts (48.46% at 435 nm and 33.46% at 820 nm) and satisfactory response times (1.92 s at 435 nm and 1.83 s at 820 nm). An electrochromic device (ECD) based on P(TTPA-co-BT) and poly(3,4-ethylenedioxythiophene) (PEDOT) was constructed and characterized. The ECD was found to have a high optical contrast, fast response time, satisfactory optical memories and good redox stability.