Tailoring trap dynamics and luminescence in SrAl2O4:Eu2+,Dy3+-Borotellurite glass composites through boron modification

Abstract

SrAl₂O₄:Eu²⁺,Dy³⁺ represents a prototypical persistent phosphor, renowned for its pronounced green emission. However, its practical application in device integration is significantly limited by inadequate thermal stability and pronounced vulnerability to degradation under certain environmental conditions. Embedding such phosphors into optimized glass matrices offers a strategy to preserve luminescence while enabling structural stability. In this work, SrAl₂O₄:Eu²⁺,Dy³⁺ phosphor was incorporated into borotellurite (BT) glasses with varying B₂O₃ content to probe the interplay between glass network modification and persistent luminescence behavior. Structural analyses confirmed the retention of SrAl₂O₄ crystallinity while embedded in the amorphous glass. The electron microscopy analysis revealed uniform phosphor dispersion in the glass. Thermal studies showed thermal stability up to 600 °C. Optical characterization showed an increase in the bandgap from 3.60 to 3.98 eV with boron incorporation in BT glass, while the composites exhibited bandgap variations arising from matrix-induced modifications of the Eu²⁺ environment. Strong green emission (∼520 nm) was retained across all composites, with subtle CIE color coordinate shift. Thermoluminescence revealed trap depths of 0.65–0.98 eV, with SrAl:BT1 composite exhibiting the most favourable trap distribution and the longest afterglow lifetime (∼8000 s). These findings establish phosphor-glass composite as a powerful route to stabilize and tune SrAl-phosphor optical properties, offering a pathway toward persistent lighting, optical data storage, security markers, and advanced photonic devices.