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.
- Award ID(s):
- 1705707
- PAR ID:
- 10108368
- Date Published:
- Journal Name:
- Journal of Materials Chemistry C
- Volume:
- 6
- Issue:
- 30
- ISSN:
- 2050-7526
- Page Range / eLocation ID:
- 8003 to 8010
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract -
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H ‐carbazole) crystal designed with donor–acceptor (carbazole–pyridine) structures under infrared excitation, simultaneously accompanied with second harmonic generation (SHG). This phenomenon indicates orderly packing donor–acceptor structures form a nonlinearly polarizable ferroelectric‐like lattice with ultralong‐lived light‐emitting states, leading to much prolonged nonlinear optical behaviors. The persistent upconversion luminescence together with SHG is largely reduced when lowering crystallinity. This implies that nonlinearly polarizable ferroelectric‐like lattice provides the necessary condition to generate persistent upconversion luminescence. Evidently, persistent upconversion luminescence becomes completely lacking when only using ultralong‐lived light‐emitting states without nonlinearly polarizable ferroelectric‐like lattice, exampled by 4‐(dimethylamino)benzonitrile dispersed in polyvinyl alcohol matrix. Magneto‐photoluminescence shows that persistent upconversion luminescence is essentially a super‐delayed fluorescence from crystalline intermolecular charge‐transfer excitons formed in the nonlinearly polarizable ferroelectric‐like lattice. Magnetodielectrics indicate crystalline intermolecular charge‐transfer excitons are coupled with nonlinearly polarizable ferroelectric‐like lattice, leading to prolonged nonlinear optical behaviors shown as persistent upconversion luminescence through super delayed fluorescence. Therefore, crystalline intermolecular charge‐transfer excitons formed in nonlinearly polarizable ferroelectric‐like lattice provide an interesting platform to generate prolonged nonlinear optical behaviors toward developing persistent upconversion luminescence under multiphoton excitation. -
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/C8TC02419G
