Solid-State Supercapacitor Constructed with Organic Electrochromic Electrodes Based on Dithienothiophene and 3,4-Ethylenedioxythiophene

Abstract

Capacitive and electrochromic behaviors of electrodeposited poly­{4,4′-[2,6-bis­(2,3-dihydrothieno­[3,4-b]­[1,4]­dioxin-5-yl) dithieno­[3,2-b:2′,3′-d]­thiophene-3,5-diyl] dibenzonitrile}, P­[E-CNDTT-E], are reported. The morphological, structural, and electrochemical properties of the polymer are determined by atomic force microscopy, Fourier transform infrared, cyclic voltammetry, spectroelectrochemical measurements, electrochemical impedance spectroscopy, and galvanostatic charging/discharging measurements. Theoretical calculations support the planarity of the structure through O···S interactions, which allow the polymer to have a low band gap of 1.43 eV. P­[E-CNDTT-E] has a high capacitance of 223 F g–1 at the current density of 1 A g–1 and displays a color change from purple to gray with an optical contrast of 30% and a coloration efficiency of 450 cm2 C–1 upon applying cathodic potential. The solid-state supercapacitor is constructed, which has a high specific capacitance of 63 F g–1 and a significant energy density of 6.5 W h kg–1. Additionally, the device retains 90% of its capacitance after 8000 cycles.