Electropolymerization of D-A-D type monomers consisting of thiophene and quionaxline moieties for electrochromic devices and supercapacitors

Abstract

Three donor-acceptor-donor (D-A-D) type monomers (ThQ-Ph, ThQ-PhOMe and ThQ-Th) based on thiophene substituted quinoxaline derivates were synthesized and further electropolymerized for electrochromic and supercapacitor applications. The present redox-active monomers were electrodeposited on the ITO electrodes robustly from their solution through the oxidative coupling reactions between thiophene radical cations. The obtained conjugated polymers (PThQ-Ph, PThQ-PhOMe and PThQ-Th) exhibited tunable and multicolor electrochromism among the visible and near infrared region with good performances. Particularly, a high optical contrast (over 80%) was achieved around 1600 ​nm, with short response time (less than 1.5 ​s) and high coloration efficiency (over 300 ​cm2 ​C-1). Moreover, quasi-solid state electrochromic devices based on the present polymers employing gel-type electrolyte were fabricated, and exhibited specific capacitance of 0.81 ∼ 1.58 ​mF ​cm-2 at the current density of 0.01 ​mA ​cm-2, which guaranteed their potential applications in energy saving smart windows.