Ferrocene-Functionalized Poly(6-(3,6-di(thiophen-2-yl)-9H-carbazol-9-yl)-hexyl Ferrocenecarboxylate): Effect of the Ferrocene on Electrochromic Properties

A novel ferrocene-containing compound 6-(3,6-di(thiophen-2-yl)-9H-carbazol-9-yl)hexyl ferrocenecarboxylate (BTC-H-Fc) was synthesized by simple chemical route, and 3,6-di(thiophen-2-yl)-9H-carbazole (BTC) was prepared for comparison. Both of the homopolymers of BTC-H-Fc and BTC were successfully synthesized by electropolymerization and kept the redox activity upon repeated cycling between 0.0 V and 1.4 V. Compared to PBTC which could only showed two colors (yellow and purple), P(BTC-H-Fc) film could exhibit four colors (yellow, awny, purple and indigo-blue) as a consequence of mixing colors of main chain and Fc group. Meanwhile, P(BTC-H-Fc) film presented higher optical contrast of 52% and more excellent coloration efficiency (573.72 cm2 C−1). All the results demonstrate that Fc could be a good choice as a functional group to improve the electrochromic properties of the electrochromic polymers.