From molecular design to adaptive devices: Triazolopyridine-Thiophene donor-acceptor type conjugated polymers for flexible patterned electrochromics in displays and near-infrared camouflage

Donor–acceptor (D–A) type conjugated polymers are a prominent class of electrochromic materials, prized for their tunable colors, high optical contrast ( ΔT ), excellent coloration efficiency ( CE ), and good stability. However, the rational design of high-performance D–A type polymers and their integration into patterned flexible displays remain challenging. In this work, we reported a series of novel triazolopyridine-thiophene D–A type precursors based on alkyl substituted 2H-[1,2,3]triazolo[4,5- c ]pyridines (PTzs) acceptors and thiophenes (Ths) donors, synthesized via the Stille coupling and subsequently electropolymerized to obtain the corresponding polymers. The resulting polymers exhibit outstanding electrochromic performance, including an optical contrastof up to 88%, an ultrahigh coloration efficiency of 1481 cm² C⁻¹ in the near-infrared (NIR) region, and remarkable cycling stability (retaining >97% activity after 5000 cycles). Furthermore, flexible electrochromic devices (ECDs) fabricated based on the optimal material show stable, reversible color switching under bending and folding conditions. Finally, we demonstrate the practical potential of this materials system by constructing patterned flexible ECDs for smart displays and adaptive NIR camouflage applications.