A new multi-electrochromic 2,7 linked polycarbazole derivative: Effect of the nitro subunit

A new poly-2,7-di-2-thienyl-9H-carbazole derivative (poly(TCT-N)) bearing nitro (–NO2) subunit has been reported. The electrochemical and optical properties of TCT-N monomer and its polymer have been compared to the 9-phenyl-2,7-di-2-thienyl-9H-carbazole (TCT) standard molecule. Cyclic voltammetry revealed that TCT-N and TCT have excellent polymerization activity; due to extended conjugation with the attached thiophene unit and also their low oxidation potentials. The oxidation potential of TCT-N is higher than that of TCT, because of electro-withdrawing effect of –NO2 moiety. Besides, the TCT-N polymeric film prepared via electrochemical process exhibits a multi-electrochromic behavior compared with TCT standard molecule. The electroactive orange color of poly-TCT-N film converted respectively to green, turquoise and dark blue upon applied positive potentials. Consequently, the polymeric electrochrome exhibits multi-electrochromic behavior, high redox stability, high coloration efficiency and reasonable response time for electrochromic applications.

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► We report here electrochemical synthesis of a new 2,7 linked polycarbazole derivative containing the –NO2 substituent.
► Synthesized monomer has excellent polymerization activity; due to extended conjugation with the attached thiophene unit.
► The polymeric film exhibits multi-electrochromic behavior, high redox stability, high coloration efficiency.