Electrostatic Self‐Assembly of Ag‐NPs Mediated by Eu<sup>3+</sup> Complexes for Physically Unclonable Function Labels
Yao Kou, Yanan Guo, Lijuan Liang, Xue Li, Yifan Wang, Pingru Su, Chun‐Hua Yan, Yu Tang
Abstract
ABSTRACT Physically unclonable functions (PUFs) are essential for anticounterfeiting. Creating high‐stability, multimode, and secure labels remains challenging. Herein, we present a novel self‐assembly method for modulating the optical signals of rare‐earth (RE) complexes via interactions with Ag nanoparticles (Ag‐NPs). Initially, we engineered a positively charged Eu 3+ complex ([EuL 3 ] 3+ ), which promotes the self‐assembly of negatively charged Ag‐NPs to form Eu/Ag‐NPs composites. The assembly of Ag‐NPs induces a surface plasmon effect that boosts the luminescent quantum yield and Raman signal intensities, and modifies the luminescence lifetime of the [EuL 3 ] 3+ . Crucially, these micron‐scale Eu/Ag‐NPs can be applied to substrates, facilitating high‐resolution signal acquisition and diverse information encoding within limited space. Validation experiments reveal that PUF labels crafted using Eu/Ag‐NPs exhibit inherent randomness and uniqueness, along with stable and repeatable signal output. The strategic self‐assembly of Ag‐NPs, mediated by [EuL 3 ] 3+ , along with the effective modulation of material properties, paves the way for advancing high‐resolution, high‐information‐density solutions in anticounterfeiting technologies.