High contrast electrochromic polymer and copolymer materials based on amide-substituted poly(dithienyl pyrrole)

Abstract

Conducting polymers have attracted attention as active materials for low power consuming, flexible devices with vivid colors and simple, room temperature processing methods. However, the conductive polymers with high-contrast electrochromic properties are limited in the literature. Here we achieve high-contrast electrochromic switching by copolymerization of newly synthesized an amide substituted dithienyl pyrrole (PBA) and 3,4-ethylenedioxythiophene (EDOT). In order to obtain the best optical properties of copolymer, spectral characteristics of the synthesized copolymers with different monomer feed ratios were investigated. Both homopolymer and copolymer films exhibit well defined redox and satisfied coloration efficiency. Spectroelectrochemistry studies indicate that the P(PBA-co-EDOT) has a lower bandgap (1.67 eV) and shows the excellent optical contrast (77% of 1000 nm) and coloration efficiency (697.01 cm2 C-1). The copolymer method provides a novel way to fabricate a freestanding organic electrochromic device. Additionally, the fluorescence properties of both monomer and polymer were investigated. P(PBA) having strong emission and good solubility and also P(PBA) has the potential to be used in OLEDs. © 2016 The Electrochemical Society. All rights reserved.