Dual‐State Dynamic Luminescence in a Microcavity‐Capped SrAl ₂ O ₄ /SrMgSi ₂ O ₇ Phosphor and CdSe/ZnS Quantum Dot Hybrid Film for Anti‐Counterfeiting and Information Encryption

Photoluminescent materials with stimuli‐responsive optical properties hold great promise for advanced anti‐counterfeiting, yet conventional static single‐mode systems are vulnerable to replication, posing a major security challenge. This study presents a novel flexible dual‐state film integrating microcavity arrays (MCA), long‐persistent luminescent (LPL) materials (green SrAl 2 O 4 : Eu 2 + , Dy 3 + and blue SrMgSi 2 O 7 : Eu 2 + , Dy 3 + ), and red CdSe/ZnS core‐shell quantum dots (QDs) within a polydimethylsiloxane (PDMS) matrix. The directional antenna effect of the MCA selectively enhances and guides emission from the upper luminescent layer, while a PDMS spacing layer isolates the lower luminescent layer from modulation, enabling tunable hue conversion. By reconfiguring the positions and types of LPL and QD layers, multidimensional optical signatures are achieved. Under single‐wavelength UV excitation, the system exhibits dual‐state dynamic optical responses, including angle‐dependent color/brightness modulation and time‐gated afterglow variation. Furthermore, a 3D dynamic luminescent code system is demonstrated, encrypting multiple information layers retrievable under specific viewing angles and time gates. This work provides a secure and information‐rich platform for next‐generation anti‐counterfeiting, optical encryption, and high‐density data storage.