Effect of EDOT contribution on the electrochromic and capacitive properties of edot-carbazole based electrochromic polymer: Electrochromic and supercapacitor device applications

Abstract

3,4-ethylenedioxythiophene (EDOT) based donor-acceptor-donor (DAD) type conjugated polymers generally have extraordinary electrochromic properties due to the excellent nature of the EDOT unit. This work investigates the electrochromic properties of such a system; EDOT-Carbazole-EDOT (ECE) based DAD type of conjugated polymer. Electrochemically synthesized homopolymer film (PECE) showed multichromic behavior with excellent optical properties such as 34 % of optical contrast, subsecond switching response (0.96 s at 478 nm), high coloration efficiency (519 cm2/C at 478 nm) and remarkable specific capacitance (3.04 F/cm2). Inserting more EDOT units into the polymer matrix of PECE via electrochemical synthesis altered the spectral and capacitive behaviors of the resulting copolymers. 2:1 (ECE:EDOT) feeded copolymer exhibited better electrochromic performance than equal feeded copolymer. On the other hand, the capacitive range and capacitance stability were significantly enhanced as the EDOT unit increased in the copolymer matrix.PECE and its copolymers were used to construct dual-type electrochromic devices with poly(3, 4-ethylenedioxythiophene) (PEDOT). ECDs of PECE and copolymers exhibited superior stability upon many switchings, with subsecond switching responses. Furthermore, ECDs can be switched effectively even at the scan rate of 500 mV/s without any loss in charge/discharge amounts. Finally, electrochromic supercapacitor device applications were performed, and a 1.5 V-LED was lighted for up to 25 s with the copolymer supercapacitor device.