A Highly Efficient White Light (Sr3,Ca,Ba)(PO4)3Cl:Eu2+, Tb3+, Mn2+ Phosphor via Dual Energy Transfers for White Light-Emitting Diodes

A series of single-phased (Sr3-x,Ca1-y-z,Ba)(PO4)(3)Cl (SCBPO_Cl):xEu(2+), yTb(3+), zMn(2+) phosphors were synthesized by high-temperature solid-state reaction, and luminescent properties of these phosphors were investigated by means of photoluminescence and microcathode luminescence (mu-CL). Under UV excitation, white-light emission was obtained from triactivated SCBPO_Cl phosphors via combining three emission bands centered at 450, 543, and 570 nm contributed by Eu2+, Tb3+, and Mn2+, respectively. White-light emission with the three emission bands is further demonstrated in the fluorescence microscope images, CL spectrum, and mu-CL mappings, which strongly confirm that the luminescence distribution of as-prepared SCBPO_Cl:xEu(2+), yTb(3+), zMn(2+) phosphors is very homogeneous. Both spectral overlapping and lifetime decay analyses suggest that dual energy transfers, that is, Eu2+ -> Tb3+ and Eu2+ -> Mn2+, play key roles in obtaining the white emission. The International Commission on Illumination value of white emission as well as luminescence quantum yield (51.2-81.4%) can be tuned by precisely controlling the content of Eu2+, Tb3+, and Mn2+. These results suggest that this single-phased SCBPO_Cl:xEu(2+), yTb(3+), zMn(2+) phosphor may have a potential application as a near-UV convertible white-light emission phosphor for phosphor-converted white light-emitting diode.