Abstract
A series of alkaline earth borophosphate phosphors, (Ba,Sr)(3)BP(3)O(12) doped with Eu(2+) ions, were synthesized by a solid state reaction. Two emission bands at 465 nm and 520 nm were attributed to the f-d transitions of doped Eu(2+) ions occupying in two different cation sites in host lattices and emission color variation was observed by substituting the M(2+) sites, which was rationalized in terms of two competing factors of the crystal field strength and bond covalence. Green and bluish-white pc-LEDs were fabricated by combination of a 370 nm near-UV chip and composition-optimized Ba(3)BP(3)O(12):Eu(2+) and (Ba,Sr)(3)BP(3)O(12):Eu(2+) phosphors, respectively. The series of phosphors may serve as a promising green and bluish-white luminescent materials used in fabrication of near UV-based white pc-LEDs.
Highlights
Phosphor-converted light-emitting diodes are potential candidates for solid-state lighting due to their excellent properties such as brightness, long lifetime, low applied voltage and high power efficiency [1,2,3]
The luminescence of Eu2+ ions in alkaline earth borophosphates with M2+BPO5 (M2+ = Ca, Sr, and Ba) composition have been studied by several groups [7,8,9] and these studies revealed that the Eu2+-doped borophosphates could be photoluminescent materials with high efficiency
The electroluminescence (EL) spectra, color rendering index (CRI), and luminous efficiency of phosphor-converted light-emitting diodes (pc-LEDs) were obtained at room temperature by using an integrating sphere
Summary
Phosphor-converted light-emitting diodes (pc-LEDs) are potential candidates for solid-state lighting due to their excellent properties such as brightness, long lifetime, low applied voltage and high power efficiency [1,2,3]. Pc-LEDs can be fabricated by combining a blue or an ultraviolet (UV) LED chip with down-converting phosphors to generate white light. The first commercial pc-LED has been produced by the combination of blue LED with yellow-emitting cerium doped yttrium aluminum garnet (YAG:Ce) phosphor. This approach suffers from thermal quenching, poor color rendition and narrow visible range. The luminescence of Eu2+ ions in alkaline earth borophosphates with M2+BPO5 (M2+ = Ca, Sr, and Ba) composition have been studied by several groups [7,8,9] and these studies revealed that the Eu2+-doped borophosphates could be photoluminescent materials with high efficiency. Green and bluish-white pc-LEDs were fabricated by combination of 370 nm LED chips and the as-synthesized phosphors
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