Patternable chiral Au nanocrystal-doped composite films for information encryption: the role of optical rotation.

Optical information encryption technology has garnered significant attention in currency security, information protection, and personal identification. While optical metasurfaces are considered ideal platforms for information encryption, their high cost and time-intensive fabrication processes have limited their widespread applications. To address this, emergent chiroptical nanomaterials offer new opportunities for information encryption through their polarization capabilities. In this study, composite films consisting of chiral Au nanocrystals embedded in curable polymers are utilized as a patternable platform for information encryption. Theoretical simulations demonstrate that chiral Au nanocrystals can rotate linearly polarized light of different wavelengths in various directions. Notably, Au nanocrystals with opposite chirality show reversed optical rotation effects for linearly polarized light while exhibiting the same extinction properties for non-polarized light. Based on these investigations, patternable composite films with embedded chiral Au nanocrystals are fabricated, showcasing their potential to encode information optical rotation. This work establishes the feasibility of chiral Au nanocrystals as a patternable platform for information encryption and presents a simple, convenient, and cost-effective approach for optical information security.