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 [Th3CNTT-TPA] (P[Th3CNTT-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[Th3CNTT-TPA] can be considered as a good candidate for multifunctional applications.