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

Abstract 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 CH 2 Cl 2 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 cm 2 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.