Author Affiliations
Hebei Key Laboratory of Optic-Electronic Information and Materials, College of Physics Science & Technology, Hebei University, Baoding , Hebei 071002, Chinashow less
Fig. 1. Relationship of the emission power and efficiency of up-conversion phosphors, host internal temperature, and excitation density
[35, 37, 40]. (a) Experimental setup for measuring the efficiency of the up-conversion phosphors; (b) relationship between emission light power and excitation light density (
x and
y represent the concentration of doped Yb
3+ and Er
3+, respectively); (c) relationship between emission efficiency and excitation light density; (d) relationship between host internal temperature and excitation light density
Fig. 2. UVC up-conversion emission properties of Er
3+ doped BaGd
2ZnO
5 under visible light excitation
[46]. (a) Up-conversion mechanism of the UV emission produced by a 532 nm solid-state laser excitation; (b) up-conversion fluorescent spectrum of Er
3+ doped BaGd
2ZnO
5 under a 532 nm solid-state laser excitation; (c) up-conversion fluorescent spectrum of Er
3+ doped BaGd
2ZnO
5 under a 460 nm LED excitation; (d) measured emission spectrum of blue LED; (e) UV emission spectrum of blue LED encapsulated with Er
3+ doped BaGd
2ZnO
5 Fig. 3. UVC up-conversion emission of LiYF
4∶Pr
3+ under the excitation of sunlight using solar-blind camera
[47]. (a) Basic working principle of solar-blind camera and ultraviolet channel imaging principle; (b)(d) UV images of LiYF
4∶Pr
3+ excited by blue LED with different excitation density and sunlight (the upper left subscript is the excitation density, the lower right subscript is the photon count emitted in UVC); (c)(e) logarithmic relationship between excitation power and emission intensity of blue LED and sunlight
Fig. 4. UV images of Pr3+ doped glass and crystal samples excited by sunlight (number is the photon count emitted in UVC). (a) Tellurite glass; (b) silicate glass; (c) phosphate glass; (d) borate glass; (e)‒(k) borosilicate glass, silicon content is 20%, 30%, 40%, 50%, 60%, 70%, 80%; (l)‒(n) KLu2F7 crystals, the Pr3+ content is 1%, 2%, 3%
Fig. 5. Up-conversion emission power measurement and application of Li
2SrSiO
4∶Pr
3+ up-conversion fluorescent materials
[48]. (a) Schematic for Up-conversion UV emission power measurement; (b) up-conversion emission power density of Li
2SrSiO
4∶Pr
3+ excited by 450-nm laser with different power; (c) design scheme of a confocal microscope for real-time observation of the microorganisms under UVC irradiation using coverslips coated with UVC up-conversion phosphors; (d) image of Li
2SrSiO
4∶Pr
3+ coated slides detected by the confocal microscope under 488-nm laser irradiation; (e) image of UVC photon detected by a solar-blind camera
Fig. 6. Morphology and luminescence properties of Li
2SrSiO
4∶Pr
3+ glassy phosphor
[49]. (a) Glassy phosphor image; (b)‒(d) emission spectra of Li
2SrSiO
4∶Pr
3+ excited by X-ray under glass, ceramic, and powder states, respectively; (e)‒(g) emission spectra of Li
2SrSiO
4∶Pr
3+ excited by 450-nm laser under glass, ceramic, and powder states, respectively, insert shows the UV images monitored by solar blind camera