Spectral Tunability of K2Lu(WO4)(PO4): Dy3+, Eu3+ Phosphors and Remote Luminescent Layers for High-Quality White Light

Dy3+ and Eu3+ co-doped phosphors have been emerged as potential candidate to generate high-quality white light under the ultraviolet (UV) or near ultraviolet (NUV) excitation for health and comfort lighting. Herein, K2Lu (WO4)(PO4) crystal has been newly developed to accommodate rare earth ions, such as Dy3+ and Eu3+ ions, to achieve spectral tunability of high-quality white light. Under NUV excitation, Dy3+ singly-doped K2Lu(WO4) (PO4) phosphors exhibit the desired blue emission at 486 nm and yellow emission at 575 nm, attributed to the electric dipole transition 4F9/2 -> 6H15/2 and the magnetic dipole transition 4F9/2 -> 6H13/2 transitions of Dy3+ ions, respectively. Interestingly, the emission color can be facilely adjusted from cold white light to pink light under 365 nm NUV excitation due to the co-doping of Eu3+ ions in K2Lu(WO4)(PO4): 0.05Dy3+ sample. Further, the remote luminescent layers containing K2Lu(WO4)(PO4): 0.05Dy3+, 0.20Eu3+ phosphor can be printed on glass substrate by screen printing technique to generate high-quality white light with the correlated color temperature (CCT) of 5433 K and color rendering index (CRI) of 87. Moreover, the remote luminescent layers exhibit better heat dissipation performance compared to conventional encapsulated LEDs and can be used as a multicolor emitting candidate for high-power white LEDs.