Thermal‐Assisted Multiscale Patterning of Nonplanar Colloidal Nanostructures for Multi‐Modal Anti‐Counterfeiting

Abstract

Nanotransfer printing of colloidal nanoparticles is a promising technique for the fabrication of functional materials and devices. However, patterning nonplanar nanostructures pose a challenge due to weak adhesion from the extremely small nanostructure‐substrate contact area. Here, the study proposes a thermal‐assisted nonplanar nanostructure transfer printing (NP‐NTP) strategy for multiscale patterning of polystyrene (PS) nanospheres. The printing efficiency is significantly improved from ≈3.1% at low temperatures to ≈97.2% under the glass transition temperature of PS. Additionally, the arrangement of PS nanospheres transitioned from disorder to long‐range order. The mechanism of printing efficiency enhancement is the drastic drop of Young's modulus of nanospheres, giving rise to an increased contact area, self‐adhesive effect, and inter‐particle necking. To demonstrate the versatility of the NP‐NTP strategy, it is combined with the intaglio transfer printing technique, and multiple patterns are created at both micro and macro scales at a 4‐inch scale with a resolution of ≈2757 pixels per inch (PPI). Furthermore, a multi‐modal anti‐counterfeiting concept based on structural patterns at hierarchical length scales is proposed, providing a new paradigm of imparting multiscale nanostructure patterning into macroscale functional devices.