Blue/blue–violet-emitting phosphate phosphors for full-spectrum white light-emitting diodes

Abstract

Violet light, a component of sunlight, is critical for human health, but it is usually ignored in classic white light-emitting diodes (LEDs) that are fabricated by pumping green, yellow, or red phosphors by blue LEDs. To realized full-spectrum white LEDs for healthy lighting, it is required to replace blue LEDs by near-ultraviolet (n-UV) or violet LEDs to pump multi-color phosphors. Herein, we reported blue and/or blue–violet phosphors of Na₃KMg₇P₆O₂₄:Eu²⁺ (NKMPO:Eu²⁺) and Na₃K_1–ySr_yMg_7–yLi_yP₆O₂₄:Eu²⁺ (NKSMLPO:Eu²⁺) that can be efficiently excited by n-UV and violet LEDs. The NKSMLPO:Eu²⁺ phosphor (y = 0.1), showing a small thermal quenching, had a photoluminescence quantum yield of 64.9% and 41.2% under 365 and 405 nm excitation, respectively. Full-spectrum white LEDs were obtained by combining n-UV or violet LEDs with the blue/blue–violet-emitting NKSMLPO:Eu²⁺ and other commercial phosphors, which show a correlated color temperature of 4285–4705 K and a maximal color rendering index of 98.4. It confirms that the NKSMLPO:Eu²⁺ phosphors can be adopted as a violet light filler for producing sunlight-like white LEDs.