In Situ Asymmetric Patterning for Information Encryption

Abstract

Here, Ag nanoparticle asymmetric assembly arrays (NAAAs) are realized through a facile and inexpensive in situ asymmetric patterning process based on plasmonic nanochemistry. The growth of Ag NPs follows the asymmetric maximum plasmonic field region of Au nanoholes under light irradiation, as demonstrated by finite-difference time-domain (FDTD) simulations. Ag NAAAs exhibit unique Fano resonance modes due to the asymmetric arrangement of the nanoparticles. The size and morphology of Ag NAAAs can be systematically tuned by adjusting the reaction duration, deposition parameters, and etching conditions. Various multiscale patterns from macroscopic to submicron scales can be precisely obtained in combination with photolithography. Ag NAAAs can serve as excellent surface-enhanced Raman scattering (SERS) substrates with an enhancement factor of up to 2.79×10⁹. Combining the adjustable asymmetric morphology and editable patterning capabilities of multiscale Ag NAAAs, the application of anti-counterfeiting labels integrating structural, molecular, and pattern/text information is realized. In addition, asymmetric patterning techniques can be used to create Au NAAAs and applied on flexible polydimethylsiloxane substrates, thereby enhancing the versatility of the anti-counterfeiting labels in practical applications.