Broadband red emission in disordered Sr2LaGaO5:Eu2+ phosphors

Abstract

Eu²⁺-doped Sr₂LaGaO₅ phosphors were prepared using a high-temperature solid-state route in a furnace at 1450 °C. Their phase, microstructure, and luminescent performance were thoroughly investigated. The XRD measurements indicate that the prepared phosphors exhibit a tetragonal phase. Upon excitation at 450 nm, the Sr₂LaGaO₅:Eu²⁺ phosphors demonstrate a broad red emission ranging from 475 to 850 nm, with a peak at 620 nm. At a doping concentration of 6 %mol Eu²⁺, the phosphors exhibit the highest emission intensity, characterized by CIE coordinates of (0.536, 0.453) and a color purity of 65.53 %. The temperature-dependent emission analysis reveals that the phosphors possess excellent thermal stability. The emission intensity of the Sr₂LaGaO₅:0.06Eu²⁺ phosphor at 420 K is about 53.9 % of the initial intensity measured at 300 K, with a thermal activation energy of 0.393 eV. The pc-WLED device was constructed via the combination of an LED chip, yellow Y₃Al₅O₁₂:Ce³⁺ and the prepared Sr₂LaGaO₅:Eu²⁺ phosphors, resulting in the emission of warm white light with a CCT value of 4985 K.