Solvent/UV driven information encryption based on a multilayer quasi-amorphous photonic heterostructure

Abstract

Herein, we demonstrate an information encryption strategy based on multilayer quasi-amorphous photonic structures (QAPS) composed of alternating arrangements of high and low refractive index materials. The designs are created by alternately spraying monodisperse SiO₂ and Fe₃O₄@SiO₂ colloidal particles as well as CdSe/ZnS quantum dots (QDs) on a specific substrate, which can realize solvent/ultraviolet (UV) driven multiple information encryption and decryption. Due to the strong light scattering of the top SiO₂ QAPS layer, the information stored in the lower Fe₃O₄@SiO₂ layer is encrypted. After infiltration of the ethanol solvent into the voids of QAPS, the SiO₂ layer becomes transparent due to the vanishing of refractive index contrast between SiO₂ and ethanol, while the Fe₃O₄@SiO₂ layer maintains bright structural color due to its high refractive index. At the same time, the information carried by QDs can be revealed under the excitation of UV light. Thus, this simple and reliable information hiding/displaying system, together with diverse encryption modes and convenient manufacturing process, makes it a potential security material to be applied in various fields.