Towards colourless‐to‐green electrochromic smart glass based on a redox active polymeric semiconductor containing carbazole moiety

Abstract

Electrochemistry and electrochromic properties of the two compounds based on carbazole core and cross-linking oxiran (CzO), and thiiran (CzS) groups have been reported. A difference of the electropolymerization and the quality of the resulting films from these starting compounds, which were deposited on indium doped tin oxide (ITO) glass electrode, has been discussed. Through diverse techniques such as cyclic voltammetry (CV), absorption, and infrared spectroscopy as well as theoretical computation, structure of proposed electroactive polymer and its charged states have also been identified and proven. It was found that the polymer with carbazole and thiiran active groups exhibited colourless in neutral, saturated green in the radical cation and green-blue in dicationic states, respectively, as well as demonstrating favourable optical contrast and satisfactory coloration efficiency. Understanding of the role of the charged states to conductivity and stability of the film in this electrochromic system, electrochemical impedance spectroscopy was applied. Degradation mechanism of this electrochromic film has been discussed. These theoretical and experimental results suggest that this newly created electroactive polymer could be promising candidate as a neutral green electrochromic material.