Inspired by ultra‑high molecular weight polyethylene (UHMWPE), we explore whether ultra‑high molecular weight (UHMW) conjugated polymers can break the performance ceiling of electrochromic devices. Multi‑scale simulations of representative p‑type, n‑type, and ambipolar UHMW systems reveal a universal “coupling bottleneck”: when morphology is optimized to the limit, charge transport becomes exclusively sensitive to π‑π stacking distance and inter‑chain electronic coupling. UHMW chains boost mobility by ~6× via trap dilution and percolation connectivity, while simultaneously enhancing mechanical toughness. To translate this into real devices, we developed a multi‑physical‑field polymerization (M3P) strategy that delivers narrow‑distribution (PDI < 1.5) ion‑channeled conjugated polymers (NDPI‑ICCPs). By integrating hydrophilic‑hydrophobic alternating side chains, crown‑ether/OEO relays, and 2D inter‑connected networks, we decouple ionic and electronic transport, reducing ion diffusion barriers to <0.1 eV and achieving electron mobilities >0.1 cm²/V·s. Prototype electrochromic smart windows and electronic paper demonstrate response times <0.3 s, contrast ΔT > 85%, color consistency ΔE < 1, and cycle life >10⁵ times. This work bridges computational insights and synthetic innovation, offering a roadmap for next‑generation flexible electrochromics.

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