RESUMO
Solution-processable electrochromic polymers (ECPs) with high performance are urgently needed for extensive applications. Nevertheless, they suffer from slow switching speed because of low ionic conductivities. Herein, we present an effective strategy to improve the contrast and switching speed in ECPs via facile side-chain engineering. A novel electrochromic thieno[3,2-b]thiophene-based polymer (PmOTTBTD) is designed and successfully synthesized by introducing oligo(ethylene oxide) side chains with high ionic conductivity. Compared to the counterpart POTTBTD without modification by oligo(ethylene oxide) chains, PmOTTBTD demonstrates nearly double contrast (42 % vs. 24 %) with a fast oxidation switching process that just takes half of the time when detected under 400â nm, as well as much higher coloration efficiencies (e. g. 239.04â cm2 C-1 vs. 226.26â cm2 C-1 @ 400â nm and 314.04â cm2 C-1 vs. 174.00â cm2 C-1 @ 650â¼700â nm). Besides, PmOTTBTD exhibits excellent stability with negligible decay after 3000 cycles. Our work suggests a facile strategy that could be adopted to realize high-performance ECPs via molecular design tuning.