High-performance electrochromic supercapacitor based on quinacridone dye with good specific capacitance, fast switching time and robust stability

Abstract

• QA dyes were designed and firstly prepared into electrochromic polymers. • The polymers with three donor units show different electrochemical behaviors. • pC10QA-2EDOT film exhibits remarkable electrochromic properties. • The device based on pC10QA-2EDOT exhibits robust cyclic stability. • The electrochromic supercapacitor can make a LED light for more than 85 s. Quinacridone (QA) dye with large π-conjugation system exhibit excellent optical, thermal and chemical properties. A series of QA derivatives (C10QA-2T, C10QA-2EDOT, C10QA-2DT) were designed and synthesized with different donor units (including thiophene, EDOT and bithiophene) in this work. Three monomers show different HOMO energy levels and onset oxidation potentials. Their corresponding polymer films were obtained by electrochemical polymerization. Compared to pC10QA-2T and pC10QA-2DT, pC10QA-2EDOT exhibits better integrated electrochromic properties in terms of multicolor showing (yellow, gray and blue), higher optical contrast (more than 40% in the visible region), larger coloration efficiency (498 cm 2 /C at 455 nm), faster switching time (less than 1 s) and better cyclic stability. It is intriguing that the electrochromic device based on pC10QA-2EDOT exhibits robust stability over 50,000 cycles with almost no decay of its original optical contrast. In addition, pC10QA-2EDOT film possesses large volume specific capacitance of up to 322 F/cm 3 , which should be ascribed to that the loose and porous structures owing to large dihedral angles caused by the steric hindrance of oxygen on the EDOT may facilitate the ion diffusion during the doping/dedoping process. Hence, the electrochromic supercapacitor can supply power to a green LED for 85 s. This work pioneers QA dye in the electrochromic field and further develops a new electrochromic energy storage device with visual color display, which may have potential prospects in portable and wearable electronic devices.