A novel narrow-band blue-emitting phosphor with high efficiency and thermal stability for WLEDs and FEDs

Abstract

For white light-emitting diodes (WLEDs), compared with the method of yellow-emitting Y₃Al₅O₁₂:Ce³⁺ phosphor pumped by a blue LED chip, tricolor phosphors combined with a near-ultraviolet (n-UV) LED chip have been regarded as a better candidate to improve the output-light performances and avoid the severe blue-light hazard. Yet, high-grade phosphors with strong absorption in the n-UV region, high efficiency and thermal stability are extremely scarce. Inspired by the mineral prototype strategy and substitution engineering, a novel Eu²⁺-doped Na₃KMg₆ZnP₆O₂₄ phosphor has been designed and developed for the first time. Its crystal structure, luminescence properties, potential application for WLEDs and cathodoluminescence properties have been studied systematically. The phosphor shows strong response to the irradiation of n-UV light and emits bright blue light peaking at 444 nm with a full width at half-maximum (FWHM) of 53 nm. The optimal Na₃KMg₆ZnP₆O₂₄:0.02Eu²⁺ sample has a high quantum efficiency of 90.2%. Interestingly, the phosphor displays zero-thermal quenching behavior, which is extremely required for high-power WLEDs. The fabricated WLED lamp can exhibit superior electroluminescence properties by using the as-prepared Na₃KMg₆ZnP₆O₂₄:Eu²⁺ phosphor as a blue-emitting component. Furthermore, the phosphor can generate stable blue light under the bombardment of electron beam. All the results suggest that the obtained phosphor can be promising in developing both WLEDs and FEDs. This work provides a new insight to design novel luminescent materials with excellent performances.