Eu2+-activated full color orthophosphate phosphors for warm white light-emitting diodes
Eu2+-doped RbBaPO4, NaCaPO4 and CsMgPO4 orthophosphate phosphors were studied. X-ray diffraction (XRD) patterns analysis indicated all of the phosphors could be obtained in a pure phase by the solid-state reaction method. The photoluminescence emission (PL) spectra revealed that the phosphors showed broad-band blue, green and red emission with peaks at near 430 nm, 510 nm and 630 nm under a 340 nm UV lamp, corresponding to RbBaPO4:0.03Eu2+, NaCaPO4:0.01Eu2+ and CsMgPO4:0.07Eu2+ samples, respectively. A white light-emitting diode (w-LED) lamp, fabricated by the three samples combining a 370 nm n-UV chip, presented a high color-rendering index (CRI) of 86, as well as a warm correlated color temperature (CCT) of 2751 K. The results indicated that Eu2+-activated full color versatile orthophosphate phosphors and mixing strategy of the similar hosts will have potential use in the design of white LEDs.