Perfluoroalkanoate‐Substituted PEDOT for Electrochromic Device Applications

Abstract The recent emergence of organic electrochromics on both the scientific and industrial levels has expedited the synthesis of new materials with varied electrochemical and optical properties. The structural versatility and broad usage of poly(3,4‐ethylenedioxythiophene) (PEDOT) has stimulated many research groups to focus on the potential of PEDOT derivatives. Here we report the first synthesis of pentadecafluoro‐octanoic acid 2,3‐dihydro‐thieno(3,4‐b)(1,4)dioxin‐2‐ylmethylester (EDOT‐F), along with its electrochemical polymerization, characterization, and incorporation into electrochromic devices (ECDs). PEDOT‐F is a cathodically coloring polymer that exhibits sub‐second switching time between a dark‐blue neutral state and a transmissive sky‐blue oxidized state, and expresses a 63 % change for both transmittance at λmax and colorimetrically determined luminance. Hexafluorophosphate‐doped free‐standing films of PEDOT‐F possess conductivities of up to 65 S cm–1. Variable transmittance ECDs constructed with PEDOT‐F and poly[3,6‐bis(2‐(3,4‐ethylenedioxythienyl))‐N‐methylcarbazole] (PBEDOT‐NMeCz) exhibit an optical contrast of 60 % at λmax (580 nm) and an overall luminance change of 60 %. Indicating the hydrophobicity of this polymer, doped PEDOT‐F exhibits a water contact angle of 110°, significantly higher than the 30° exhibited for the doped PEDOT parent.