An efficient blue-emitting Sr5(PO4)3Cl:Eu2+ phosphor for application in near-UV white light-emitting diodes

A series of Eu2+ doped Sr-5(PO4)(3)Cl blue-emitting phosphors was prepared by conventional high-temperature solid-state reactions. The crystal structure, electronic structure, reflectance spectra, thermal stability and quantum efficiency of the Sr-5(PO4)(3)Cl:Eu2+ phosphor, as well as its application in near-UV white light-emitting diodes have been investigated. The optimization of the lattice parameters and the electronic structure of the Sr-5(PO4)(3)Cl host matrix have been calculated based on density functional theory (DFT). The crystal structure of Sr-5(PO4)(3)Cl:Eu2+ was confirmed by X-ray diffraction. The concentration quenching of Eu2+ ions in the Sr-5(PO4)(3)Cl host is determined to be 1.0 mol% and the physical mechanism of concentration quenching can be explained by the dipole-dipole interaction. Through theoretical calculation, the color purity of the as-prepared Sr-5(PO4)(3)Cl:Eu2+ phosphor is found to be much better than the commercial compound, blue-emitting BaMgAl10O7:Eu2+ (BAM:Eu2+). In particular, a near-UV white LED was fabricated by using an InGaN-based near-UV LED chip (395 nm) and a mixture of Sr-5(PO4)(3)Cl:Eu2+, green-emitting (Ba, Sr)(2)SiO4:Eu2+ and red-emitting CaAlSiN3:Eu2+ phosphors. The obtained LED device exhibits an excellent color-rendering index (R-a = 94.65) at a correlated color temperature of 3567.84 K with CIE coordinates (0.3952, 0.3709). The above results suggest that the Sr-5(PO4)(3)Cl:Eu2+ phosphor is a promising blue-emitting phosphor for application in near-UV white light-emitting diodes.