Mengjiao Xu,Yi Ding,Wanxia Luo,Luxiang Wang,Suxia Li,Yanhong Liu
A new multicolor-emitting Tb 3+ -Eu 3+ codoped KAlP 2 O 7 (KAPO) phosphor was synthesized by solid-state reaction under the air atmosphere. The synthesis, morphology, luminescence properties , energy transfer mechanisms and thermal stability of the synthesized phosphor were systematically investigated. The codoped phosphor exhibited the characteristic emission of Eu 3+ at 612 nm ( 5 D 0 - 7 F 2 ) and Tb 3+ at 544 nm ( 5 D 4 - 7 F 5 ). Under ultraviolet (UV) excitation, KAPO: Tb 3+ , Eu 3+ shows tunable emission from green-yellow to red with increasing of Eu 3+ concentration due to efficient Tb 3+ -Eu 3+ energy transfer. Based on the decay curves, the energy transfer from Tb 3+ to Eu 3+ was classified to be of dipole-dipole interaction resonant type with energy transfer efficiency of ~97%. The excellent luminescent properties and remarkable thermal stabilities suggested that KAPO: Tb 3+ , Eu 3+ is a promising UV-converting material for the fields of lighting and displays.
Broad-band near-infrared (NIR) phosphors are essential to assembling portable NIR light sources for applications in spectroscopy technology. However, developing inexpensive, efficient, and thermally stable broad-band NIR phosphors remains a significant challenge. In this work, a phosphate, KAlP2O7, with a wide band gap and suitable electronic environment for Cr3+ equivalent substitution was selected as the host material. The synthesized KAlP2O7:Cr3+ material exhibits a broad-band emission covering 650–1100 nm with a peak centered at 790 nm and a full width at half-maximum (fwhm) of 120 nm under 450 nm excitation. The internal quantum efficiency (IQE) was determined to be 78.9%, and the emission intensity at 423 K still maintains 77% of that at room temperature, implying the high efficiency and excellent thermal stability of this material. Finally, a NIR phosphor-converted light-emitting diode (pc-LED) device was fabricated by using the as-prepared material combined with a 450 nm blue LED chip, which presents a high NIR output power of 32.1 mW and excellent photoelectric conversion efficiency of 11.4% under a drive current of 100 mA. Thus, this work not only provides an inexpensive broad-band NIR material with high performance for applications in NIR pc-LEDs but also highlights some strategies to explore this class of materials.
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