Orange super-long persistent luminescent materials: (Sr1-xBax)3SiO5:Eu2+,Nb5+

 Mater. Chem. Front., 2021, 5, 333-340

image file: d0qm00488j-f1.tif

Persistent luminescent materials are widely used as night-vision and marking materials in various important fields. Although significant achievements have been made in blue and green persistent luminescent (PersL) materials, the research and development of PersL materials in the warm-color region (550–660 nm) are relatively lacking. Only the orange PersL phosphor Y2O2S:Eu3+,Mg2+,Ti4+ (∼610 nm) and deep red PersL phosphor (Ca1−xSrx)S:Eu2+,Tm3+ (∼650 nm) fulfill the demands of commercial applications. However, sulfide phosphors have poor chemical stability and a relatively short persistent duration time. Herein, we report a series of orange PersL materials, (Sr1−xBax)3SiO5:Eu2+,Nb5+, which exhibit a strong PersL emission band at 550–670 nm and a super-long persistent time of more than 20 h at the 0.32 mcd m−2 threshold value after UV radiation. These new orange PersL materials are compared to the commercial warm-color sulfide PersL phosphor, Y2O2S:Eu,Mg,Ti, with regards to PersL time and brightness, and it is determined that they would have great potential applications.

Infrared-photostimulable and long-persistent ultraviolet-emitting phosphor LiLuGeO4:Bi3+,Yb3+ for biophotonic applications

Mater. Chem. Front., 2021,5, 1468-1476

Graphical abstract: Infrared-photostimulable and long-persistent ultraviolet-emitting phosphor LiLuGeO4:Bi3+,Yb3+ for biophotonic applications

Photodynamic therapy needing ultraviolet (UV) in deep tissue is hindered due to the low biological tissue penetration ability of UV light. Here, we demonstrate a persistent ultraviolet-emitting phosphor, LiLuGeO4:Bi3+,Yb3+, which can be re-stimulated by near infrared (NIR) light. Yb3+-doping significantly enhances the trap density without changing the thermoluminescence peak positions. The phosphor can be effectively activated by a 254 nm lamp and exhibits prominent persistent luminescence peaking at 350 nm. The decay time can be recorded much longer than 15 h. This phosphor exhibits simulated in vivo photostimulated persistent luminescence after a longtime decay by using in vitro NIR light penetrating biological tissue. Combined with CaAlSiN3:Eu2+, red persistent luminescence from Eu2+ is obtained. LiLuGeO4:Bi3+,Yb3+ makes up the shortage of excellent UVA persistent phosphors. It is expected to have potential applications as an in vivo renewable excitation source to trigger photosensitizers or fluorescent probes when used for biophotonic applications.