Polythiophene Class Of Conductive Polymer Electrochromic Properties

π-Conjugated polymers have been considered as promising materials holding unique optical and electrical properties, and have been widely applied in the fields of polymer solar cells (PSCs), electrochromic devices, sensors, polymer light emitting diodes (PLEDs), and so on. These electroactive and photoactive polymers are usually based on thiophene, pyrrole, phenylene, fluorene, or carbazole moieties. Among EC materials, thiophenes are a class of important EC conjugated polymers because of their high electrical conductivity and good redox property. They exhibit fast switching times, outstanding stability and high contrast ratios in the visible and NIR regions in their EC applications. Meanwhile, thiophenes have facile band gap (E_g) tunability through structural modification, which present various electrochromic properties.The synthesis of these conjugated polymers can be carried out by either chemical or electrochemical method. The yield of products obtained from chemical routes is very low and the synthesis cost is very high, while electrochemical polymerization has been proved to be one of the most useful approaches for conjugated polymers synthesis. In this study, syntheses of conjugated polymers have been carried out by electrochemical method.1,4-Bis(2-thienyl)-benzene and 1,4-bis(2-thienyl)-naphthalene monomers are successfully synthesized via coupling reaction. Their Polymers are successfully achieved by electrochemical oxidation of their monomers in acetonitrile (ACN) containing sodium perchlorate (NaClO₄), respectively. The resultant polymers are investigated by cyclic voltammetry (CV) and characterized by FT-IR, ¹H NMR, and UV–vis spectra. Spectroelectrochemistry results reveal that the resulting polymer films have distinct electrochromic properties. Their applications in electrochromic devices (ECDs) are discussed. At the other hand, the copolymers are successfully achieved by electrochemical oxidation of the monomer mixtures in acetonitrile (ACN) containing sodium perchlorate (NaClO₄). The obtained copolymers have poly(carbazole-co-pyrene), poly(carbazole-co-pyrene) and poly(1,4-bis(2-thienyl)-benzene-co-3,4-ethylenedioxythiophene). Cyclic voltammetry (CV), ¹H NMR, UV–vis and FT-IR analyses confirm that the resulting polymer is a copolymer. Spectroelectrochemistry of copolymer films are investigated in detail, which reveal that copolymer films have good electrochromic properties.Polythiophene and its derivatives, as a class of important electrochromic materials, have been easily achieved by electrochemical oxidation of the monomer or their monomer mixtuers, which present various electrochromic properties. With the in-depth research in theory and the application of new technology, thiophene electrochromic materials will play an important role in the future electrochromic applications.