A novel high-quality electrochromic material from 3,4-ethylenedioxythiophene bis-substituted fluorene

Poly(2,7-bis (2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9H-fluorene) (P(EDOT-FE)), a novel electrochromic material obtained from 3,4-ethylenedioxythiophene (EDOT) bis-substituted fluorene (FE) in CH2Cl2 solution, and its applications in electrochromic devices (ECD) are discussed. The external EDOT units will not only function as donor groups but also lower the oxidation potential. Fluorescent spectral studies indicate that P(EDOT-FE) with high fluorescence quantum yields and photochemical stability is a novel green-light-emitter. P(EDOT-FE) is switched between brown in the reduced state and blue in the oxidized state. ECD based on P(EDOT-FE) and poly(3,4-ethylenedioxythiophene) (PEDOT) was also fabricated and showed a good electrochromic performance. The ECD constructed by P(EDOT-FE) and PEDOT has good optical contrast (36% at 625 nm), high coloration efficiency (784 cm2 C−1), fast response time (0.5 s at 625 nm), better optical memory and long-term stability. Clear change from dark red (neutral) to dark blue color (oxidized) of ECD is demonstrated with robust cycle life. These results provide an avenue for applications of PEDOT family in electrochromic devices.

Graphical abstractNovel high-quality poly(2,7-bis (2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9H-fluorene) (P(EDOT-FE)) was prepared by electrochemical polymerization for the first time. P(EDOT-FE) can switch between brown in the reduced state and blue in the oxidized state. The dual-type electrochromic device based on P(EDOT-FE) and PEDOT shows strong color changes with higher coloration efficiency and optical contrast, better optical memory and stability.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A novel electrochromic material obtained from EDOT bis-substituted fluorene is discussed. ► ECD has high coloration efficiency, fast response time and better optical memory. ► Clear change from dark red to dark blue color of ECD is demonstrated with robust cycle life.