BaLiZn₃(PO₄)₃:Eu²⁺: Ultranarrow-Band Violet Emission in a Highly Symmetric Crystal Structure

The development of narrow-band emitting phosphors is still a pivotal challenge for light-emitting diode (LED) backlights in liquid-crystal displays (LCDs). Hereon, an effective tactic is raised to develop a novel narrow-band violet emission in Eu²⁺-doped BaLiZn₃(PO₄)₃ with a highly symmetric site and rigid crystal structure. Under the ultraviolet (UV) light excitation of 334 nm, this novel BLZPO:Eu²⁺ shows a super narrow-band violet emission at 387 nm with a full width at half-maximum (fwhm) of 11 nm at 7 K and 18 nm at 298 K, respectively. Such an ultranarrow-band emission has never been achieved in the previous Eu²⁺-doped phosphors. Moreover, this as-prepared BLZPO:Eu²⁺ phosphor presents small photoluminescence (PL) thermal quenching, and its PL intensity maintains 82.6% at 150 °C and 70% at 200 °C of the initial PL intensity at room temperature. The as-fabricated LED utilizing BLZPO:Eu²⁺ with the n-UV LED exhibits potential anticounterfeiting application. This study offers a novel idea to achieve the supernarrow-band emission of Eu²⁺-activated phosphors based on the highly symmetric crystal structure.