Sacrificial‐Layer‐Assisted Heat‐Affected‐Zone Suppression in Laser Patterning of PET for High‐Performance Flexible Devices

ABSTRACT Laser ablation of polymers produces a heat‐affected zone (HAZ) and material redeposition, even when using ultrashort‐pulse lasers. Here, we demonstrate a sacrificial‐layer strategy for nanosecond laser cutting of PET that suppresses the HAZ, with no HAZ detected by SEM, AFM, Raman spectroscopy, or XPS, through thermal‐boundary‐condition engineering during ablation, while eliminating material redeposition through sacrificial‐layer liftoff. Finite element method (FEM) thermal simulations show that the sacrificial coating enhances heat dissipation away from the ablation zone compared to the native PET–air interface. Due to its high optical transparency and thermal stability, a CA600 acrylic emulsion reduces localized heating and enables clean, high‐resolution patterning. To demonstrate the utility of this approach, we fabricate embedded Ag mesh electrodes in PET that combine high transparency, ultralow sheet resistance, EMI shielding, and Joule‐heating capability. The resulting electrodes achieve a figure of merit up to 12100, corresponding to more than an order‐of‐magnitude improvement over previously reported direct‐on‐substrate laser‐fabricated transparent conductors.