Effect of oxygen vacancy on photoluminescence properties of Dy3+ doped K2BaCa(PO4)2 phosphor and remote luminescence multi-layer for white light

Abstract

Dy3+ ions singly-doped phosphors, emerging as single-component white light-emitting phosphors, have been regarded as a promising candidate for white light generation under ultraviolet (UV) or near-ultraviolet (NUV) excitation. Here, a series of Dy3+ doped K2BaCa(PO4)2 phosphors with single phase was successfully synthesized by solid-state reaction method. Under NUV excitation, K2BaCa(PO4)2: Dy3+ phosphors exhibits the desire blue emission at 490 nm and yellow emission at 580 nm, attributed to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions, respectively. Interestingly, the broad emission peak centered at 458 nm can also be found and assigned to the oxygen vacancy in K2BaCa(PO4)2 host lattice. Significantly, the emission intensity of the phosphor is greatly enhanced to 4.1 times higher than that of the sample without oxygen vacancy due to the energy transfer from oxygen vacancy to Dy3+ ions. K2BaCa(PO4)2: 0.03Dy3+ phosphor with high quantum yield of 76.9% exhibits good thermal stability with the relative emission intensity of 95.7% and 88.6% at 323 K and 373 K, respectively. Subsequently, the white light with correlated color temperature (CCT) of 4521 K and color rendering index (CRI) of 79 can be achieved for the optimized K2BaCa(PO4)2: 0.03Dy3+ phosphor packaged with NUV LED chip (365 nm). Further, the remote luminescence multi-layer based on K2BaCa(PO4)2: 0.03Dy3+ phosphors is fabricated on glass substrate by screen printing technology and exhibit better heat dissipation performance than that of the conventional NUV LEDs, which can be a promising candidate of single-component phosphors for the manufacture of white LEDs with adjustable remote luminescent layers.