Abstract
Visible-light and infrared-light persistent phosphors are extensively studied and are being used as self-sustained glowing tags in darkness. In contrast, persistent phosphors for higher-energy, solar-blind ultraviolet-C wavelengths (200–280 nm) are lacking. Also, persistent tags working in bright environments are not available. Here we report five types of Pr3+-doped silicates (melilite, cyclosilicate, silicate garnet, oxyorthosilicate, and orthosilicate) ultraviolet-C persistent phosphors that can act as self-sustained glowing tags in bright environments. These ultraviolet-C persistent phosphors can be effectively charged by a standard 254 nm lamp and emit intense, long-lasting afterglow at 265–270 nm, which can be clearly monitored and imaged by a corona camera in daylight and room light. Besides thermal-stimulation, in bright environments, photo-stimulation also contributes to the afterglow emission and its contribution can be dominant when ambient light is strong. This study expands persistent luminescence research to the ultraviolet-C wavelengths and brings persistent luminescence applications to light.
Highlights
Decay time (h) be effectively filled by 254 nm light
We found that highly coordinated silicate-containing compounds, the silicates used for Ce3+-activated persistent phosphors or mechanoluminescence phosphors (e.g., Ca2Al2SiO7:Ce3+ and Lu2SiO5:Ce3+), are the suitable hosts for Pr3+ UVC afterglow after 254 nm light irradiation
Our study shows that these Pr3+-doped silicate UVC persistent phosphors can be effectively charged by a standard 254 nm lamp and emit intense, long-lasting (~10 h) afterglow at 265–270 nm
Summary
Decay time (h) be effectively filled by 254 nm light. The host should be capable of creating a suitably strong crystal field environment to ensure a small Stokes shift that is required for efficient Pr3+ 4f15d1 → 4f2 transitions[14,15,16,17,18]. We found that highly coordinated silicate-containing compounds, the silicates used for Ce3+-activated persistent phosphors or mechanoluminescence phosphors (e.g., Ca2Al2SiO7:Ce3+ (refs.23–25) and Lu2SiO5:Ce3+ (refs.26,27)), are the suitable hosts for Pr3+ UVC afterglow after 254 nm light irradiation. We identified five types, more than ten kinds of silicates for Pr3+ UVC afterglow, including melilites, M2Al2SiO7 (M = Ca, Sr); cyclosilicates, M3Y2Si6O18 (M = Ca, Sr, or Sr + Ca); silicate garnets, M3X2Si3O12 (M = Ca, Sr; X = Al, Al + Ga, or Al + Y); oxyorthosilicates, R2SixO3+2x (R = Lu, Y; x = 1 or 2); and orthosilicates, LiRSiO4 (R = Y, Lu). Our study shows that these Pr3+-doped silicate UVC persistent phosphors can be effectively charged by a standard 254 nm lamp and emit intense, long-lasting (~10 h) afterglow at 265–270 nm. The results of other types of silicates are given in Supplementary Information
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