Polycarbazole Electropolymerization Materials with Excellent Electrochromic Performance Based on Phenothiazine/Phenoxazine Group

Electrochromic small molecules suffer from the difficult film processibility and serious dissolvability at their oxidation state, which greatly limit their applications in electrochromic areas. Here, well-defined electrochemical polymer structures, pCZ-FSQ and pCZ-FEQ, are obtained by taking advantage of the unique electrochemical dimerization of carbazole, and low redox-potential phenothiazine and phenoxazine groups are introduced as an electrochromic color-changing unit with the interruption of conjugation between them via an alkyl chain linkage. The obtained polymer films pCZ-FSQ and pCZ-FEQ are composed of the independent dimeric carbazole and organic small molecule units. Finally, they exhibit outstanding electrochromic properties with optical contrast of more than 50%, switching time of less than 1 s, excellent stability (over 500 cycles of optical stability), and ultrahigh coloration efficiency (276 cm 2 C −1 for pCZ-FSQ , 384 cm 2 C −1 for pCZ-FEQ). This is thought to be greatly attributed to the well-defined electrochemical polymer structures with dual electrochromic color-changing properties of both phenothiazine/phenoxazine and dimeric carbazole. This can also provide some implications for the future in-depth study of small molecule electrochromism and the solution to the problem of difficult processing of small molecules.