Garnet-structured persistent luminescence phosphor Ca₃Al₂Ge₃O₁₂:Cr³⁺ for dynamic anticounterfeiting applications

Area of Science:

• Materials Science
• Solid-State Chemistry
• Optoelectronics

Background:

• Fluorescent materials are crucial for anti-counterfeiting, but existing phosphors face challenges like disordered sequences and forgery.
• Current multifunctional phosphors for anti-counterfeiting struggle with detection difficulties and susceptibility to counterfeiting.

Purpose of the Study:

• To develop a novel, flexible dual-mode anti-counterfeiting system.
• To address limitations of existing anti-counterfeiting technologies, including disordered reading and ease of forgery.
• To create a robust material for multi-layer information encryption.

Main Methods:

• Synthesized a series of Ca3Al2Ge3O12:Cr3+ (CAG) phosphors with varying Cr3+ doping concentrations (2%-6%).
• Investigated deep red persistent luminescence properties, with a peak emission at 722 nm.
• Conducted thermoluminescence (TL) experiments to analyze material defects and their role in long persistent luminescence (LPL).

Main Results:

• Adjusting Cr3+ concentration modulated the intensity and duration of deep red persistent luminescence.
• Analysis revealed that material defects contribute to both deep and shallow traps, significantly enhancing LPL.
• Demonstrated successful implementation in various anti-counterfeiting and information encryption formats (QR codes, bar codes, etc.).

Conclusions:

• The developed CAG phosphors offer a flexible and simple dual-mode anti-counterfeiting solution.
• The material's enhanced LPL, attributed to specific defect structures, provides a robust platform for security applications.
• This work presents a new approach for designing multifunctional luminescent materials for advanced anti-counterfeiting and encryption.