Enhanced NIR Electrochromic Properties of Corannulene-(triphenylamine)₅ and EDOT-Derived Polymers via Electrochemical Layer-by-Layer Polymerization Compared to Copolymerization

This study explores the electrochemical and electrochromic properties of polymers derived from corannulene-(triphenylamine)₅ (CT) and 3,4-ethylenedioxythiophene (EDOT) through electrochemical copolymerization and layer-by-layer polymerization techniques. To address the high oxidation potential of EDOT, an EDOT dimer (BiEDOT) was synthesized, which facilitated successful copolymerization with CT. The resulting copolymer films, P10 and P8, exhibit enhanced near-infrared (NIR) electrochromic properties, with P8 showing better performance in NIR absorption. Comparative analysis with layer-by-layer films (PLs) reveals distinct electrochemical behaviors with PLs demonstrating higher NIR and lower visible absorbance with improved optical properties. Among PLs, PL6 exhibits the best NIR absorbance at 0.6 V, while the absorbance of the others does not show a significant increase until 0.7 V. Additionally, it also demonstrates excellent switching properties, with only a 3% loss of optical contrast at 1400 nm after 500 switching cycles. The study concluded that layer-by-layer polymerization offers an effective method for constructing PCT-PEDOT electrochromic films, providing better performance and higher NIR absorption than copolymerized films.