Tunable warm white emission in Eu3+/Dy3+ co-doped K2Y(WO4)(PO4) phosphors for solid-state lighting

A series of K 2 Y(WO 4 )(PO 4 ): Dy 3+ , Eu 3+ phosphors have been successfully developed via solid-state reaction method to generate color-tunable warm white light. Based on the phase identification and microstructure analysis, Dy 3+ ions singly-doped and co-doped phosphors all exhibit single phase of K 2 Y(WO 4 )(PO 4 ) crystal, demonstrating the substitution of Y 3+ ions by Dy 3+ ions in host lattice. Under near ultraviolet (NUV) excitation of 350 nm, Dy 3+ singly-doped K 2 Y(WO 4 )(PO 4 ) phosphors emit a cold-white light with correlated color temperature of 9266 K comprised by blue emission peak at 486 nm and yellow emission peak at 578 nm, which are attributed to 4 F 9/2  →  6 H 15/2 and 4 F 9/2  →  6 H 13/2 electronic transitions of Dy 3+ ions, respectively. Further, Eu 3+ and Dy 3+ ions are co-doped K 2 Y(WO 4 )(PO 4 ) host and Eu 3+ ions can be acted as red emission centers to achieve tunable photoluminescence properties in a single-phased phosphor excited by NUV chip with wavelength of 394 nm. It is proved by the photoluminescence spectra of Eu 3+ and Dy 3+ ions co-doped samples that there exist the energy transfer between Dy 3+ ions and Eu 3+ ions in the KYWP host, which belongs to the electric dipole-electric dipole interaction. Finally, CIE color coordinates of the generating white light by K 2 Y(WO 4 )(PO 4 ): Dy 3+ , Eu 3+ phosphors can be facilely adjusted from (0.3601, 0.3427) to (0.5161, 0.3547) with the increasing Eu 3+ ions concentration. The warm white light with tunable color temperatures of 4409 K, 3042 K, 2566 K and 1976 K can be achieved for K 2 Y(WO 4 )(PO 4 ): Dy 3+ , Eu 3+ phosphors, indicating a potential application in NUV white light emitting diodes.