Synthesis of a Multifunctional Quinoxaline and Benzodithiophene Bearing Polymer and Its Electrochromic Device Applications

Abstract

A quinoxaline (Qx) and benzodithiophene (BDT) comprising of random copolymers, namely poly(5‐(6‐(5‐(4,8‐bis((2‐ethylhexyl)oxy)benzo[1,2‐b:4,5‐b′]dithiophen‐2‐yl)‐4‐(2‐ethylhexyl)thiophen‐2‐yl)‐4,8‐bis ((2‐ethylhexyl)oxy)benzo[1,2‐b:4,5‐b′]dithiophen‐2‐yl)‐2,3‐bis(3,4‐bis(octyloxy)phenyl)quinoxaline) (PQBT), is synthesized via Stille polycondensation reaction. To investigate the effect of the π‐bridge on the electrochromic properties, 3‐(2‐ethylhexyl) thiophene is incorporated the between Qx and BDT moiety. The resulting random copolymer is characterized by NMR spectroscopy, gel permeation chromatography (GPC), attenuated total reflectance−Fourier‐transform infrared spectroscopy (ATR−FTIR), and scanning electron microscopy (SEM). PQBT exhibits ambipolar and multichromic characteristics and is highly soluble in common solvents. Optoelectronic studies reveal two well‐separated absorption bands having maxima at 500 and 532 nm with 1.83 eV optical band gap (Egop). PQBT exhibits orange color in the neutral state with brown, green, and blue colors in the intermediate, oxidized, and reduced states, respectively. Subsequently, a PQBT and poly‐3,4‐ethylenedioxythiophene (PEDOT)‐bearing prototype bilayer electrochromic device working between orange and blue colors is constructed and characterized.

Synthesis and Characterization of Conjugated Polymers Based on Thieno[3,4‐b]Thiophene Quinoidal Unit

“…[ 1–5 ] The applications in organic electronics, such as organic thin‐film transistors (OTFTs), have driven scientific researchers to continuously explore high‐performance CPs. [ 6–13 ] CPs exhibit good charge transport performances originated from the strong intermolecular π‐orbital overlap as well as enhanced interchain interactions. [ 14–17 ]…”