High-Resolution Roll-to-Roll Additive Patterning of Functional Materials on Large Areas via Topographic Discontinuous...

Two-dimensional (2D) arrays of nanoscale functional materials are essential for the advancement of cutting-edge technologies in optics and photonics, optoelectronics, and sensor systems. Conventional fabrication techniques for these structures, however, are limited by high energy consumption, significant waste, and scalability challenges. To address these issues, we demonstrate a roll-to-roll (R2R) additive nanopatterning process, offering a sustainable and scalable solution for large-area, high-resolution production of 2D metamaterials. Our process combines UV-based R2R nanoimprinting and topographical discontinuous dewetting (TDD) to pattern functional inks with feature sizes down to tens of nanometers over large areas. Central to this method is the use of UV-curable Norland Optical Adhesive (NOA) as the imprintable resin. Although the exact composition of NOA is proprietary, this study reveals its thermally switchable wetting properties, transitioning from a high-surface energy state (γ_s = 36.6 ± 2.3 mJ m^-2) to a low-surface energy state (γ_s = 16 ± 0.5 mJ m^-2) after annealing at 150 °C. This property of NOA enables it to function as an ideal substrate for large-area TDD. During TDD, inks are selectively deposited into the recessed areas of the annealed NOA patterns, while dewetting occurs on the elevated surfaces. The additive nature of this technique significantly reduces ink consumption─requiring only approximately 100 nL for a 10 cm² substrate in continuous R2R operations─ensuring that almost all of the functional material is utilized effectively. This method accommodates a wide array of functional materials, such as metals, semiconductors, and dielectrics, and allows for control over pattern thickness and multilayer configurations. Focusing on sustainability and scalability, the proposed additive R2R nanopatterning technique enables eco-friendly large-area production of nanoscale functional materials, driving progress in metamaterials, optoelectronics, and other advanced fields.