Enhanced blue emission and afterglow properties of Sr2MgSi2O7:Eu2+, Dy3+ phosphors for flexible transparent labels

Abstract

Long afterglow is a fascinating luminescence phenomenon exhibited by certain storage phosphors that emit visible light after being stimulated by ultraviolet rays. Strontium magnesium silicate phosphors doped with europium and dysprosium (Sr2MgSi2O7:Eu2+, Dy3+) have garnered attention in recent years. Enhancing the afterglow performance of these phosphors remains a significant challenge. In this study, we investigate the enhancement of afterglow performance in Sr2MgSi2O7:Eu2+, Dy3+ phosphors prepared via a sol–gel auto-combustion method using commercial silica (CS) and lab-made nanosilica (NS). Our results reveal that the afterglow performance of the NS-based phosphor is significantly improved, glowing with optimal intensity for a prolonged period compared to the CS-based phosphor. Time-resolved photoluminescence studies show that the average lifetime of the NS-based phosphor is enhanced tenfold compared to the CS-based phosphor, attributed to the improved crystallinity of the NS-based phosphor. Photoluminescence studies indicate that both phosphors exhibit comparable performance. Thermoluminescence studies suggest that the presence of multiple trap levels with varying trap depths in the NS-based phosphor allows it to exhibit extended afterglow emission than the CS-based phosphor. Structural, morphological, and optical properties of the phosphors were analyzed using x-ray diffraction, Fourier transform infrared, x-ray photoelectron spectroscopy, field emission scanning electron microscopy, and UV–vis techniques. The underlying mechanism of the afterglow is explained in detail. The prepared phosphor was used to create flexible and transparent labels with silicone rubber, which can serve as indicators during dark hours.