An electrochromic device based on all-in-one polymer gel through in-situ thermal polymerization

• All-in-one electrochromic (EC) gel was successfully prepared by thermal curing.
• The proposed gelled EC device reveals a transmittance change of 67.1% at 620 nm.
• Incorporating polymer matrix greatly enhanced the write–erase ability of the ECD.
• Low-driving voltage of 0–0.5 V was required in switching the gelled EC device.

A self-standing all-in-one electrochromic gel utilizing phenyl viologen (PV) and N,N,N′,N′-tetramethyl-1,4-phenylenediamine (TMPD) as the electrochromic materials is prepared by incorporating a thermo-cured cross-linked polymer matrix. The thermal-cured polymer matrix can prevent the agglomeration of PV happening on the electrode surface, resulting in the excellent write–erase ability of the obtained gelated ECD. Moreover, the cross-linker which possesses the long propoxylated arms leads to the easier diffusion for both PV and TMPD in the obtained polymer network. As a result, the obtained ECD exhibits a large transmittance change (ΔT>67% at 620 nm) within a short response time (<3.5 s) under an extremely low driving voltage (0.5 V). Besides, this device remains over 55% of ΔT after 10,000 cycles of switching.

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