Persistent phosphors for the future: Fit for the right application

Abstract

When the bright green-emitting SrAl2O4:Eu,Dy persistent phosphor was described in the literature in 1996, this presented a real breakthrough in performance, both in terms of initial brightness and afterglow duration. Since then, many new persistent phosphors, with emission spanning from the ultraviolet to the near infrared, have been developed. Very few materials, however, reach a similar afterglow time and intensity as SrAl2O4:Eu,Dy, which is still considered the benchmark phosphor. The present paper discusses the reasons for this—seemingly—fundamental limitation and gives directions for further improvements. An overview is given of the preparation methods of persistent phosphors and their properties. Much attention is paid to the correct evaluation of a persistent phosphor in absolute units rather than vague terms or definitions. State of the art persistent phosphors are currently used extensively in emergency signage, indicators, and toys. Many more applications could be possible by tuning the range of trap depths used for energy storage. Very shallow traps could be used for temperature monitoring in, for example, cryopreservation. Deeper traps are useful for x-ray imaging and dosimetry. Next to these applications, a critical evaluation is made of the possibilities of persistent phosphors for applications such as solar energy storage and photocatalysis.

Cut-flower Carnation Photoluminescence: Potential New Value-added Product

“…Most glow-in-the-dark materials use the phosphors zinc sulfide or the newer strontium aluminate, whereas highlighters use pyranine or fluorescein. Glow-in-the-dark or photoluminescent materials carry phosphors that absorb low-energy light and then re-emit visible light as luminescence or glow (Poelman et al, 2020). The addition of UV light excites the phosphors, resulting in ordinary luminescence and persistent luminescence as charge carriers are transferred from the activator to the traps, and those traps are filled gradually, storing excitation energy (Poelman et al, 2020).…”

“…Glow-in-the-dark or photoluminescent materials carry phosphors that absorb low-energy light and then re-emit visible light as luminescence or glow (Poelman et al, 2020). The addition of UV light excites the phosphors, resulting in ordinary luminescence and persistent luminescence as charge carriers are transferred from the activator to the traps, and those traps are filled gradually, storing excitation energy (Poelman et al, 2020). Low-energy light (red light) can be used to excite some phosphors, but highenergy photons, found in the UV band, are most effective at charging the traps.…”

Near‐Infrared Persistent Luminescence and Trap Reshuffling in Mn4+ Doped Alkali‐Earth Metal Tungstates

“…To date, persistent phosphors have been widely applied in the fields of luminous paints, safety displays, emergency signage, information storage, alternating current-driven light emitting diodes (LEDs), and artificial synapses. [1][2][3][4][5] The utilization of near-infrared (NIR) persistent luminescence for in vivo imaging brought NIR persistent phosphors into the bioimaging field. By using a high-intensity 808 or 980 nm laser, repeated long-term imaging can obtained from photostimulated luminescence via releasing energy from captured traps.…”

NIR emitting GdVO4:Nd nanoparticles for bioimaging: The role of the synthetic pathway

“…The detection of the emitted light is classified as "time-gated" as it occurs few microseconds after the excitation pulse, in order to cut off short-living tissues' autofluorescence, with a decay time of the order of 100 ns 9 . The main advantage of the proposed method compared to persistent phosphors thus is the possibility to keep tracking the particles for a very long time (as long as they remain in the body), well past the time persistent luminescence would have decayed to the point of becoming unmeasurable 10 .…”