Efficient, stable, broadband cyan‐emitting Ca‐substituted Ba9Lu2Si6O24:Eu2+ with multisite luminescence for NUV‐wLEDs

Abstract

AbstractIn order to develop an efficient and stable broadband cyan phosphor for full spectrum white lighting emitting diodes (wLEDs), novel Ba9Lu2Si6O24:Eu2+, xCa2+ is designed and synthesized. Ca‐substitution induces Eu2+ ions into Lu3+ crystallographic site, which achieve rare nonequivalent cation substitution of Eu2+. Effects of Ca‐substitution on crystal structure of matrix and phosphor are investigated by X‐ray photoelectron spectroscopy, X‐ray powder diffraction, transmission electron microscopy, and density functional thoery (DFT). Ba9Lu2Si6O24:Eu2+, xCa2+ can be effectively excited by with near‐ultraviolet (NUV) and exhibit broadband cyan emission with full width at half maximum (FWHM) of 119.7 nm at x = 0.2, due to the multisite luminescence centers. For the sample x = 0.2, the internal quantum efficiency is 92.61%, and the luminous intensity at 423 K remains 89% of that measured at room temperature. The rigid structure of [SiO4]‐[LuO6]‐[SiO4] doped with Eu2+ ion makes Ca‐substituted samples exhibit excellent luminescence efficiency and thermal stability. Our work develops a significant strategy based on multisite cation regulation to explore NUV‐excited broadband cyan phosphors for full spectrum wLEDs.