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Tunable photoluminescence from YTaO4: Bi3+ for ultraviolet converted pc-WLED with high chromatic stability
摘要： To avoid the color drift of WLED at high temperature, it is significant to develop color stable luminescent materials. Herein we report on a phosphor YTaO4:Bi3+ with a stable blue emission upon ultraviolet excitations even as the temperature changes between 300 and 480 K. Upon excitations into host absorptions a tunable blue emission can be led from 400 nm to 450 nm due to the enhanced energy transfer efficiency from host to bismuth ions as the concentration of bismuth increases. As excitation scheme is modulated between 355 and 370 nm the white emission can be achieved in the compound of YTaO4 single doped with Bi3+, which has rarely been reported previously. For proof of concept the prototype WLEDs have been demonstrated with the phosphor YTaO4:Bi3+ and the 365 nm InGaN chips under different driving currents. Our findings make it possible for single phase white emitting phosphors activated by a single ion of Bi3+ for WLEDs, and also can inspire to develop WLED devices with high chromatic stability.
关键词： YTaO4:Bi3+,ultraviolet excitation,chromatic stability,white light emitting diodes,phosphor
更新于2025-09-23 15:19:57
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Synthesis, energy transfer mechanism, and tunable emissions of novel Na3La(VO4)2:Re3+ (Re3+ = Dy3+, Eu3+, and Sm3+) vanadate phosphors for near-UV-excited white LEDs
摘要： In this study, novel Eu3+-, Dy3+-, and Sm3+-activated Na3La(VO4)2 phosphors were synthesized using a solid state reaction method. X-ray diffraction analysis results indicated that the Na3La(VO4)2 phosphors had an orthorhombic crystal structure with the Pbc21 space group. There were two different La(1)O8 and La(2)O8 polyhedra with high asymmetry in the crystal structure. Scanning electron microscopy revealed that the product had a sheet morphology with an irregular particle size. Further, the luminescence properties, including the excitation and emission spectra, and luminescence decay curve, were investigated using a fluorescence spectrometer. The results showed that the Na3La(VO4)2 compound was an excellent host for activating the luminescence of Eu3+ (614 nm), Dy3+ (575 nm), and Sm3+ (647 nm) ions. Further, Dy3+/Eu3+ co-doped Na3La(VO4)2 phosphors were exploited, and the energy transfer from Dy3+ to Eu3+ was demonstrated in detail by the photoluminescence excitation, photoluminescence spectra, and luminescent decay curves. The results showed that the energy transfer efficiency from Dy3+ to Eu3+ was highly efficient, and the energy transfer mechanism was dipole–dipole interactions. Finally, tunable emissions from the yellow region of CIE (0.3925, 0.4243) to the red region of CIE (0.6345, 0.3354) could be realized by rationally controlling the Dy3+/Eu3+ concentration ratio. These phosphors may be promising materials for the development of solid-state lighting and display systems.
关键词： Vanadate phosphor,White LED,Energy transfer,Lighting and display,Near ultraviolet excitation,Tunable emissions
更新于2025-09-16 10:30:52