X-ray-Excited Long-Lasting Narrowband Ultraviolet-B Persistent Luminescence from Gd³⁺-Doped Sr₂P₂O₇ Phosphor

Abstract

Persistent phosphors emitting in the narrowband ultraviolet-B (NB-UVB) spectral region have aroused significant interest, owing to their special self-illuminating feature in realizing many advanced technological applications under excitation-free conditions, such as dermatological therapy and invisible optical tagging. Here, we focus our discussion on a new Gd 3+ -doped persistent phosphor, Sr 2 P 2 O 7 :Gd 3+ , which exhibits long-lasting NB-UVB persistent luminescence peaking at 312 nm for more than 24 h after charging by an X-ray beam. The NB-UVB light emission from the charged Sr 2 P 2 O 7 :Gd 3+ phosphor can be clearly detected by a UVB camera in bright indoor environment. More importantly, the enhancement of NB-UVB afterglow intensity and decay time can be observed under continuous photostimulation of polychromic indoor ambient light. Furthermore, applying charged Sr 2 P 2 O 7 :Gd 3+ phosphors as invisible optical taggants, clear and interference-free recognition of the encrypted message and location of different objects have been realized due to the lack of UVB light in bright indoor environment. The as-prepared Sr 2 P 2 O 7 :Gd 3+ persistent phosphor is expected to offer new directional solutions for the development and application of ultraviolet luminescence technology.

Long-persistent far-UVC light emission in Pr3+-doped Sr2P2O7 phosphor for microbial sterilization

“…Compared to the persistent luminescence emission in the darkness, an obvious enhancement of the UVC afterglow intensity was observed after the initial 1 hour decay, as the illuminance increased from 100 to 500 lux. Subsequently, crossover started to appear for the afterglow decay curves, but the UVC afterglow intensity in the bright ambient light environment was still higher than that in the darkness due to the continuous photostimulation of polychromic ambient light, 34,51,52 indicating that the SPO:0.005Pr 3+ phosphor has promising application prospects in both dark and bright environments. The absolute UVC afterglow intensity at 222 nm was also measured by an optical power meter with a UV silicon photodetector.…”

“…The sample was pre-irradiated by X-ray for 20 min. chromic ambient light, 34,51,52 indicating that the SPO:0.005Pr 3+ phosphor has promising application prospects in both dark and bright environments. The absolute UVC afterglow intensity at 222 nm was also measured by an optical power meter with a UV silicon photodetector.…”

Trap engineering through chemical doping for ultralong X-ray persistent luminescence and anti-thermal quenching in Zn2GeO4

“…The high energy X-ray excitations can result in the distribution of photogenerated charge carriers in all the trap states. 50 Thus, the long PersL in Zn 2 GeO 4 could be achieved by tailoring the defect states in between the bandgap by doping.…”

Narrowband Ultraviolet-B Persistent Luminescence in an Indoor-Lighting Environment through Energy Transfer from Host Excitons to Gd3+ Emitters in ScPO4

“…However, the stable Gd 3+ 4f 7 electronic configuration makes it hard to be oxidized or reduced in an inorganic matrix, which effectively blocks the charge carrier transfer between Gd 3+ and energy traps. Consequently, Gd 3+ usually cannot directly act as an emitting center in a persistent phosphor, and most NB-UVB persistent phosphors are realized by the persistent energy transfer from the sensitizers (e.g., Pr 3+ , Bi 3+ , and Pb 2+ ) to Gd 3+ emitter after the stoppage of 254 nm UV lamp irradiation. − Recently, the emergence of X-ray as an excitation source to realize PersL has significantly expanded the family of persistent phosphors and provided enhanced control over PersL properties because of the appealing features of X-ray such as high photon energy and high penetrating ability. − Thus, X-ray charging opens a door to convert the existing Gd 3+ -doped luminescent materials into NB-UVB persistent phosphors in large band gap hosts; − however, a clear understanding of the nature of energy traps and the associated PersL mechanism still remains a challenge.…”