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Wu et al. Soft Sci 2024;4:29 https://dx.doi.org/10.20517/ss.2024.21 Page 9 of 22

Figure 5. Recent advances in active layers pattern design. (A) A multicolor ECD based on the bowknot-like patterned WO layer on the
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Cr/Ag-PET electrode with thermal deposition method. Reproduced with permission [92] . Copyright 2024, Elsevier; (B) Flexible ECD with
logo content based on the PEDOT micropattern with localized electrochemical polymerization method using agarose template.
Reproduced with permission [78] . Copyright 2021, ACS Publications; (C) Flexible ECD fabricating based on 2D ordered Ag/W O
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nanowires network with LB technique. Reproduced with permission [33] . Copyright 2017, ACS Publications. ECD: Electrochromic display;
PET: polyethylene terephthalate; PEDOT: poly(3,4-ethylenedioxythiophene); 2D: two-dimensional; LB: Langmuir-Blodgett.
Ag/W O NW network has been formed on the ITO-PET substrate by a novel Langmuir-Blodgett (LB)
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technique as the transparent electrode, following the patterned W O NW film with different masks was
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assembled via the same technique for its application as electrochromic patterned or pixelated displays
[Figure 5C] . The W O NW film was firmly combined with the network electrode with this
[33]
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nanostructure construction, which protects the AgNWs layer for enhanced chemical stability and shows
stable and satisfactory electrochromic performances with a large interface surface area. This strategy offers a
novel micro-nano scalable approach to manufacturing a high-performance flexible ECD.
Interestingly, feasible ways are emerging, such as simply involving a transparent insulating template [PVA,
polyvinyl chloride (PVC), photoresist film] in the electrochromic device forming the patterned content. The
pre-patterned PVC sheet between the electrolyte and Fe-based metallo-supramolecular polymer (polyFe)
electrochromic film on the ITO-PET substrate ensures that the film in contact with the electrolyte
undergoes the electrochemical oxidation and shows the patterned content [Figure 6A] . Besides, a highly
[66]
uniform and transparent patterned dielectric PVA layer has been closely screen-printed on the ITO-PET
electrode and forms 1-methyl-4,4’-bipyridyl iodide (MBI) patterning via in-situ electrochemical processing
on the uncovered area of the electrode [Figure 6B] . Besides, the patterned, insulated photoresist film has
[62]
been firmly deposited on the ITO-PET electrode through ultraviolet (UV) irradiation with a
photomask [73,93] . The flexible ECD was fabricated by transferring three different viologen derivative gels on
the ITO-PET substrate, showing red-green-blue (RGB) colors under -0.7 V [Figure 6C] . Moreover, the
[73]
photolithography process of the viologen-based soluble electrochromic layer was simplified by integrating it
with UV-curable ion gel, which can be cured on SWCNT/Pd-coated AgNWs (PCSNs) bilayer electrode-