The research team of the High Power Laser Unit Technology Laboratory of the Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences has made new progress in multiple anti-counterfeiting based on dual emission centers in single component.

Focusing on the demands for multiple luminescent color changing anti-counterfeiting of single component materials, the team proposed a double emission mechanism of main group elements co-doped with rare earth ions, tuned visible light emission colors based on multiple influencing factors such as excitation wavelength, element types, doping concentrations and ambient temperature, designed letter hiding and flower color change experiments. The anti-counterfeiting verification system confirms the anti-counterfeiting potential of Ca₃Y₂Ge₃O₁₂:0.01Bi³⁺, Ln³⁺(Eu³⁺/Er³⁺) phosphors. Related research results have been published in Ceramics International on February 20, 2023.

The extensive elemental inclusion ability of garnet structure provides the basis for dynamic photoluminescence of dual emission centers; single component dual emission anti-counterfeiting materials based on rare earth ions/main group ions have become potential targets for safety anti-counterfeiting materials due to their advantages of diverse patterns, strong color recognition, and high replication difficulty; the commonly used excitation light sources (254 nm, 285 nm, 303 nm, 365 nm, 976 nm) are inherent advantages in promoting the commercialization of anti-counterfeiting materials.

In research, the team successfully synthesized Bi³⁺/Ln³⁺ co-doped Ca₃Y₂Ge₃O₁₂ crystallites with both excitation-wavelength-dependent and color-adjustable ability. The free combination of fluorescent powder materials has successfully achieved word information hiding and dynamic flower color changing design, greatly improving information storage capacity, increasing decryption difficulty, and ensuring the security of anti-counterfeiting applications. The multi-mode complex color-changing design with common light sources provides experimental basis and theoretical guidance for optimizing the preparation and application of anti-counterfeiting materials.

Fig. 1. (a) Emission spectra of Bi³⁺, Eu³⁺ series phosphors. (b) Dual-emission energy transfer mechanism. (Image by SIOM)

Fig. 2. (a) Information hiding experiment. (b) Flower discoloration experiment. (Image by SIOM)

Article Website:
https://doi.org/10.1016/j.ceramint.2023.02.156

Contact:
WU Xiufeng
General Administrative Office
Shanghai Institute of Optics and Fine Mechanics, CAS
Email: xfwu@siom.ac.cn
Web: http://english.siom.cas.cn/