Electrochromic property of a copolymer based on 5-cyanoindole and 3,4-ethylenedioxythiophene and its application in electrochromic devices

•A novel electrochromic copolymer obtained from EDOT and 5-cyanoindole is discussed.•The copolymer presents distinct color changes with good optical contrast and response time.•Clear change from brown to dark blue color of ECD is demonstrated with robust cycle life.

The spectroelectrochemical and electrochromic properties of a novel copolymer (P(CNIn-co-EDOT)) obtained from 3,4-ethylenedioxythiophene (EDOT) and 5-cyanoindole (CNIn) were discussed. P(CNIn-co-EDOT) can change between purple in the reduced state and blue in the oxidized state. Electrochromic devices (ECDs) based on P(CNIn-co-EDOT) and poly(3,4-ethylenedioxythiophene) (PEDOT) were also fabricated. This as-prepared ECD showed good optical contrast (48% at 630 nm), high coloration efficiency (680 cm2 C−1), fast response time (0.8 s at 630 nm), good optical memory and long-term stability. Clear change of ECD from brown (reduced state) to dark blue color (oxidized state) was demonstrated with robust cycle life.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide