Highly stable viologens-based electrochromic devices with low operational voltages utilizing polymeric ionic liquids

[Display omitted] •Asymmetrical 1-alkyl-1′-aryl substituted viologen and polyviologen were synthesized.•Viologens-based electrochromic devices with polymeric ionic liquids were assembled.•The ECDs exhibited well electrochromic behavior.•Cyclic stability over 96% of initial transmittance change after 4000 cycles of switching. In this work, we proposed an effective route of introducing poly(ionic liquid) (PIL) gel as electrolyte to suppress dimer formation of viologen radical cation during switching in electrochromic devices (ECDs). The ECDs were fabricated based on ion gels consisting of various viologens, PIL and ferrocene (Fc). We found that incorporation of PIL contributed to the suppression of dimer production. The suppression of dimer formation can provide ECDs with improved colouration efficiencies, faster switching times, longer cycle lives, and potentially reduced costs. The results showed that an excellent cyclic stability over 96% of initial transmittance change after 4000 cycles of switching.