Spectral tunability of K2Lu(WO4)(PO4): Dy3+, Eu3+ phosphors and remote luminescent layers for high-quality white light

Dy 3+ and Eu 3+ 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, K 2 Lu(WO 4 )(PO 4 ) crystal has been newly developed to accommodate rare earth ions, such as Dy 3+ and Eu 3+ ions, to achieve spectral tunability of high-quality white light. Under NUV excitation, Dy 3+ singly-doped K 2 Lu(WO 4 )(PO 4 ) phosphors exhibit the desired blue emission at 486 nm and yellow emission at 575 nm, attributed to the electric dipole transition 4 F 9/2  →  6 H 15/2 and the magnetic dipole transition 4 F 9/2  →  6 H 13/2 transitions of Dy 3+ 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 Eu 3+ ions in K 2 Lu(WO 4 )(PO 4 ): 0.05Dy 3+ sample. Further, the remote luminescent layers containing K 2 Lu(WO 4 )(PO 4 ): 0.05Dy 3+ , 0.20Eu 3+ 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.