Temporal dynamic photochromic materials for advanced anticounterfeiting

Abstract

The intriguing optical phenomena of photochromism and photoluminescence, when integrated into a solitary material, can offer innovative applications in optical memory devices and multimode anti-counterfeiting. However, the exploration and utilization of such materials with dynamic anti-counterfeiting still presents a substantial challenge. This study puts forth an innovative strategy to attain a convergence between the photochromic absorption peak and the photoluminescent emission peak, fundamental to the creation of high-efficiency dynamic anti-counterfeiting materials. By sintering in a reducing atmosphere, a large number of oxygen vacancies are introduced into Ba₃MgSi₂O₈:Er³⁺ ceramics, which exhibits a reversible white-pink color change with excellent fatigue resistance upon alternate 330 nm illumination and thermal stimulus. Furthermore, Ba₃MgSi₂O₈:Er³⁺ ceramics demonstrate a distinct fluorescence emission, transitioning from yellow-green to orange to red under 330 nm continuous irradiation. This fascinating behavior can be attributed to the fluorescence resonance energy transfer process, facilitating efficient energy transfer between the luminescent centers and coloring centers. The exceptional optical properties exhibited by Ba₃MgSi₂O₈:Er³⁺ ceramics have enabled the successful implementation of dynamic anti-counterfeiting applications in this study. This advancement is anticipated to fuel endeavours towards luminescence modulation instigated by photochromism.