Red-emitting CaLa4(SiO4)3O:Eu3+ phosphor with superior thermal stability and high quantum efficiency for warm w-LEDs

Abstract

To accelerate the next generation of high power white light-emitting diodes, the development of efficient and stable red-emitting phosphors is urgent. In this regard, a series of CaLa4(SiO4)3O:Eu3+ phosphors with red-emitting band centered at 612 nm are prepared by a high temperature solid state reaction. X-ray diffraction patterns and Rietveld refinement confirm that all the samples are oxyapatite structure with space group of P63/m. Impressively, the quantum efficiency of the prepared red phosphor reaches as high as 97.5% under blue light excitation, and its emission intensity at 423 K remains 82.4% of that at room temperature, which are comparable to those of the commercial Y2O3:Eu3+ red phosphor. As a consequence, a warm white light-emitting diode with a luminous efficiency of 84.9 lm/W, a correlated color temperature of 4012 K and a color rendering index of 84.4 is realized by blending red-emitting CaLa4(SiO4)3O:Eu3+ phosphors and yellow-emitting Y3Al5O12:Ce3+ ones with a blue LED chip. It is expected that the explored CaLa4(SiO4)3O:Eu3+ red phosphor can be a good candidate for application in solid-state lighting.