Nonstoichiometry-Induced Self-Activated Phosphors for Dynamic Anti-counterfeiting Applications

Area of Science:

• Materials Science
• Optoelectronics
• Solid-State Chemistry

Background:

• Advanced anti-counterfeiting strategies leverage unique optical signal properties like contactless operation and rapid identification.
• Achieving multi-color, multi-temporal, and multi-modal luminescence simultaneously presents a significant challenge in optical security materials.

Purpose of the Study:

• To develop a dynamic, self-activated luminescence material for advanced anti-counterfeiting applications.
• To explore the relationship between intrinsic defects, particularly oxygen vacancies, and luminescence properties in nonstoichiometric zinc germanate.

Main Methods:

• Synthesis of nonstoichiometric zinc germanate (Zn2GeO4) with modulated intrinsic defects.
• Investigation of photoluminescence (PL) properties under varying ultraviolet (UV) irradiation times.
• Analysis of temperature-dependent luminescence emission.
• Observation of long persistent luminescence (LPL) and photostimulated luminescence (PSL) behaviors.

Main Results:

• A dynamic self-activated luminescence was achieved in nonstoichiometric Zn2GeO4, modulated by intrinsic defects.
• Increased oxygen vacancy concentration enhanced self-activated luminescence performance.
• Photoluminescence color shifted from green to blue-white with prolonged UV irradiation.
• Emission color varied from blue to green with increasing temperature (280–420 K).
• Observed green long persistent luminescence (LPL) and photostimulated luminescence (PSL).

Conclusions:

• Nonstoichiometric Zn2GeO4 exhibits dynamic luminescent properties responsive to temperature and photon stimulation.
• The material's tunable optical characteristics provide a sophisticated platform for advanced anti-counterfeiting technologies.
• This work presents a promising direction for the future evolution of anti-counterfeiting solutions.