A Microporous Bifunctional Electrochromic Energy‐Storage Polymer of Thiophene, Triphenylamine, and Thienothiophene

The novel monomer, 4‐(2‐(4‐(bis(4‐(thiophen‐2‐yl)phenyl)amino)phenyl)‐5‐(thiophen‐2‐yl)thieno[3,2‐ b ]thiophen‐3‐yl)benzonitrile, is synthesized by applying Suzuki coupling reaction and electropolymerized directly onto indium tin oxide coated glass electrode surface to obtain a conjugated microporous polymer of [Th 3 CNTT–TPA] (P[Th 3 CNTT–TPA]). The morphology and structure of the polymer film are characterized by atomic force microscopy, Fourier transform infrared, and UV–visible spectroscopies. Electrochemical properties are studied using cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic charge–discharge, and chronoamperometric measurements. Its gravimetric capacity and capacitance values are measured to be 65 and 235 F g −1 at a current density of 3 A g −1 , respectively. It shows high energy and power densities of 65 and 32.5 kWh kg −1 , respectively, and exhibits high coloration efficiency of 513 C −1 cm 2 in visible region, switching between yellow and grey colors. Three different electrochromic–supercapacitor devices, that is, one symmetrical (energy storage device (ESD)1) and two asymmetrical, using poly(3,4‐ethylendioxythiophen) (ESD2) and poly(3,4‐propylenedioxypyrrole) (ESD3) as counter electrodes, are fabricated. The asymmetrical device, ESD3, demonstrats better capacity and stability. Regarding the cyclic stability and electrochromic‐energy‐storage properties, P[Th 3 CNTT–TPA] can be considered as a good candidate for multifunctional applications.