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

• Published in: Macromolecular chemistry and physics 2020-03, Vol.221 (6), p.n/a
• Main Authors: Yasa, Mustafa, Surmeli, Seher, Depci, Tolga, Toppare, Levent, Hacioglu, Serife Ozdemir
• Format: Article
• Language: English
• Subjects: Absorption spectra; conducting polymers; Copolymers; Electrochromic cells; electrochromic devices; Electrochromism; Liquid chromatography; multifunctional polymers; NMR spectroscopy; Optoelectronics; Polycondensation reactions; Quinoxalines; Spectrum analysis
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.201900470

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. In this study, synthesis, electrochromic−spectroelectrochemical properties, and electrochromic device applications of a novel conjugated polymer bearing quinoxaline and benzodithiophene (BDT) moieties are reported. The polymer PQBT is synthesized via Stille polycondensation reaction. The designed bilayer electrochromic device operates between orange and blue colors.