The Synthesis and Photoluminescence Properties of Novel Sr8(Al12O24)(WO4)2: Eu2+ Green-Emitting Phosphors for White LEDs

Abstract

Phosphors, as the crucial material of phosphor-converted white light-emitting diodes (pc-WLEDs), have played an essential role in improving luminescent efficiency and regulating color rendering index (CRI). Hence, we have successfully synthesized a novel Eu²⁺ doped Sr₈(Al₁₂O₂₄)(WO₄)₂ (SAWO) green phosphor for the first time using the solid-state reaction, as well as systematically investigated its phase and crystal structure, luminescent properties, and thermal stability. The SAWO:x mol%Eu²⁺ (0.1 ≤ x ≤ 1.0) phosphors were confirmed to be pure phase through XRD Rietveld refinement. The excitation spectrum of SAWO:Eu²⁺ monitored at 516 nm exhibited a wide band from 250 to 450 nm, which is well matched with the PL spectrum for near-ultraviolet chips. Furthermore, it can be known that three distinct Sr³⁺ sites in as-synthesized samples are occupied by Eu²⁺ to form a broad emission band of 430–650 nm by the analysis of the crystal structure and spectra. Meanwhile, the optimal doping concentration of Eu²⁺ is 0.3 mol%, and the concentration quenching mechanism is electric dipole–dipole interactions. Additionally, the SAWO:Eu²⁺ phosphor shows higher color purity (82.0%) and excellent activation energy (ΔE = 0.312 eV). These results demonstrate that the SAWO:Eu²⁺ has remarkable potential as the green ingredient in a tricolor phosphor excited by near-ultraviolet in pc-WLEDs.