Corannulene Extended Viologen-Based Ambipolar Polymers for Transparent-to-Color Electrochromic Supercapacitors
Jing‐Ju Huang, Hsuan-I Liang, Hsing‐An Lin, Shyh‐Chyang Luo
Abstract
This paper describes ambipolar polymers made of penta(N-alkyl carbazole)-corannulene extended viologen for use as an electrochromic supercapacitor. Electrochromic supercapacitors with visible energy storage levels and high charge/discharge rates have been used to power wearable and portable intelligent electronics. Redox-active π-conjugated polymers have received significant attention because they can change color and store energy through a faradaic reaction during the doping/dedoping process. However, conjugated ambipolar polymers used as electrochromic supercapacitors generally display color at both neutral and doped states because of the extensive conjugation of the donor and acceptor units. The alkyl chain as a nonconjugated linker bridged the donor and acceptor units to help retain the electrochromic behaviors of the individual unit and pursue a transparent-to-color electrochromic supercapacitor. Still, the length of the alkyl chain affects the optical contrast and specific capacitance of the polymers. An ambipolar polymer with a butyl chain as linker displays the highest optical contrast and the best performance of specific capacitance at 291 and 394 F g–1 in the p-doping and n-doping regions, respectively. Finally, the ambipolar polymer was applied to fabricate a gel-type electrochromic device, which demonstrates a transparent-to-green switching during the charge/discharge process.