Research On The Syntheses And Their Electrochromic Properties Of The Soluble Conducting Polymers Containing Quinoxaline Or Triphenylamine Unit

Conducting polymers have arisen public concern due to their unique optical and electrical properties as well as good electrochromic properties. As a kind of organic electrochromic materials, conducting polymers have been widely used in various fields such as polymer light-emitting diodes, photovoltaic devices, sensors, smart windows, camouflage materials, electrochromic devices and so on. Electrochromic conjugated polymers have been the emphasis of research owning to the huge advantages of excellent stabilities, fast response times, high optical contrasts and fine-tuning of the band gaps by structure modification.In this article, monomers were successfully designed and synthesized based on D-A theory. And then four novel D-A type quinoxaline-containing thiophene derivatives(PFBOTQ, PMFBOTQ, PFBTQ and PMFBTQ) were synthesized by electropolymerization. Similarly, two novel D-A type quinoxaline-containing selenophene derivatives(PFSQ and PMFSQ) based on selenophene as the donor units were also electrochemically synthesized. The optical and electrical properties as well as electrochromic properties of the six D-A type polymers were characterized in detail by employing cyclic voltammetry(CV), scanning electron microscopy(SEM), step profiler and UV-Vis-NIR spectroscopy. Electrochemical and spectroelectrochemistry analyses demonstrated that all six polymers exhibited both p- and n-type doping characteristics. Three polymers of PFBOTQ, PMFBOTQ and PFSQ presented lower band gaps, lower oxidation potentials, excellent electrochemical and spectroelectrochemically kinetic stabilities. It was noteworthy that three polymers of PFBOTQ, PMFBOTQ and PMFSQ exhibited a green color in the neutral state and presented a highly transmissive near colorless hue in the oxidized state, which made the polymers important applications in the field of electrochromism.Besides, the novel triphenylamine derivatives were synthesized by structure modification for triphenylamine monomer. And then four monomers of triphenylamine-containing thiophene derivatives were achieved via Stille coupling reaction of triphenylamine derivatives with thiophene derivatives. Meanwhile the corresponding polymers(PNETPA, PNMOTPA, PNMTPA and PNTTPA) were obtained by electrochemical method. The optical and electrical properties as well as electrochromic properties of four polymers were characterized in detail by using cyclic voltammetry(CV), scanning electron microscopy(SEM), step profiler and UV-Vis-NIR spectroscopy. Electrochemical measurements and spectroelectrochemistry analyses demonstrated that both PNETPA and PNMOTPA also showed lower oxidation potentials, lower band gaps and outstanding electrochromic switching properties.These experimental results showed that the above ten newly synthetic polymers could realize the tunableness of the band gap and polymers exhibited different the optical and electronic properties as well as electrochromic properties owing to the differences of electron-donating abilities of their donor units. All polymers showed excellent electrochemical and spectroelectrochemically kinetic stabilities, high optical contrasts(ΔT%) and fast response times and satisfactory coloration efficiencies(CE). These excellent properties would make them well application prospect in the field of electrochromism.