The near-IR photo-stimulated luminescence of CaS:Eu²⁺/Dy³⁺nanophosphors

Abstract

We report on the synthesis, the characterization and the optical properties of CaS:Eu 2+ /Dy 3+ nanophosphors. We demonstrate the generation of strong red light emission following NIR excitation of the CaS:Eu 2+ /Dy 3+ nanophosphors.

Persistent and Photostimulated Red Emission in CaS:Eu2+,Dy3+ Nanophosphors

“…However, if the traps are deeper the carriers may reside there for an infinite time if no external stimulation is provided. These traps may be activated to release the carriers by photostimulation, which results in the recombination of electrons and holes to produce the emission of visible light known as photo­stimulated luminescence . These storage phosphors have found a number of application such as in optical information write‐in and read‐out, erasable and rewritable optical memory media for many advanced optical storage applications and in the field of biomedical luminescence probes for bioanalysis and bioimaging .…”

“…We have recently reported the synthesis of an inorganic insulator optical nanophosphor CaS:Eu 2+ , Dy 3+ which exhibits both persistent and red photostimulated luminescence (PSL) upon UV and 980 nm irradiation, respectively. [2a] Encouraged by this observation we have undertaken a detailed study to elucidate the trapping centers using thermoluminescence. Thermoluminescence measurements generate glow curves from which the activation energy and the number of trapping centers may be determined.…”

“…The persistent luminescence time of the nanophosphor is significantly improved using an irradiation wavelength of 254 nm in comparison to 312 nm light, which was used in our previous study. [2a] In addition, we obtained nanoparticles with a narrower particle size distribution using ultrasonication from the initial polydispersed and large nanophosphors. This persistent and photostimulated nanophosphor shows a long afterglow time of about 5 h before reaching the background value of the CCD detector when irradiated using an UV lamp emitting at 254 nm at a power of 6 W for 10 min and a maximum PSL time of 18 ± 2 min using 980 nm excitation at powers as low as 29 mW.…”

Energy harvesting and conversion mechanisms for intrinsic upconverted mechano-persistent luminescence in CaZnOS

“…20,21,37,83 Eqn (9) and (10) show the cases of single luminescence peaks within different charge states due to the subtle interplay of multi-defect reactions. For a single persistent luminescence peak with ÀU eff for O-defects, eqn (11) seems to be valid in many cases.…”

Chemically engineered persistent luminescence nanoprobes for bioimaging

“…A limit with current probes is their long term chemical stability in vivo . In the future, researches using biodegradable materials could be envisioned such as recently reported by Capobianco and co-workers 148. Another promising application of such nanoprobes is their use as theranostic agents.…”