High-performance red@green core-shell emitting nitride phosphor with monodisperse Eu2+ luminescence centers for solid state lighting

• Sr 2 Si 5 N 8 @SrSi 2 O 2 N 2 :Eu 2+ phosphors are prepared by deposition-precipitation process. • Red@green core-shell emission and monodisperse Eu 2+ activators are achieved. • The relative intensity of Red/green emission can be adjusted by SiO 2 /Sr 2 Si 5 N 8 ratio. • WLEDs device is fabricated by dispersing the phosphor in Sn-F-P-O glass. The red@green core-shell emitting phosphor with monodisperse luminescence center was successfully constructed by Eu 2+ doped Sr 2 Si 5 N 8 and Sr 2 Si 5 N 8 @SrSi 2 O 2 N 2 via a deposition-precipitation (DP) method. Compared to traditional solid state reaction (SSR) method, under excitation at 370 nm, Sr 2 Si 5 N 8 :0.05Eu 2+ phosphor prepared by DP method exhibits red emission at 611 nm and an ~1.4-fold luminescent intensity enhancement. Interestingly, upon near-ultraviolet (NUV) excitation, Eu 2+ doped Sr 2 Si 5 N 8 @SrSi 2 O 2 N 2 phosphors prepared by DP method exhibit a dual emission feature with the green emission at 538 nm and red emission peak at 611 nm. The elemental line scanning spectrum of the energy dispersive X-ray analysis indicates a core@shell structure of Sr 2 Si 5 N 8 @SrSi 2 O 2 N 2 . Furthermore, this red@green core-shell emitting phosphor can be encapsulated in ultra-low melting Sn-F-P-O glass to achieve the white light with excellent color quality Ra = 85) and low correlated color temperature (4484 K) when pumped by near ultraviolet LED chips.