Multielectrochromic copolymers of 3,4-ethylenedioxythiophene and naphthalene prepared via electropolymerization in boron trifluoride diethyl etherate

Copolymers based on 3,4-ethylenedioxythiophene (EDOT) and naphthalene have been successfully prepared via electropolymerization in boron trifluoride diethyl etherate. Cyclic voltammograms, FTIR, and XPS confirm the formation of copolymers. The EDOT/naphthalene ratio in the polymer chain increases with applied increasing EDOT/naphthalene feed ratio. The copolymers exhibit multicolor electrochromism, and the color can be tuned by controlling the applied feed ratio. The copolymer prepared with EDOT/naphthalene at 8/1 displays multiple colors under various potentials, which presents absorption peak at 531 nm and 1.7 eV in the neutral state. The bleaching and coloration times at 531 nm are 1.2 and 3.6 s, respectively. Furthermore, the copolymer has good optical and electrochemical stability, which only loses 2% of its contrast after 500 steps, and 14% of its electroactivity after 1000 cycles.

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► Copolymers based on naphthalene and EDOT have been electrochemically prepared in BFEE solution.
► FTIR and XPS characterizations confirm the formation of copolymers.
► The resultant copolymers present multicolor and tunable electrochromism.
► The copolymer films present reasonable switching response, coloration efficiency, and good optical, electrochemical stability.