Mixed‐Phase and Solid‐Solution in Single Particles Yielding Better Phosphors

Abstract Enhancing phosphor luminescence efficiency is always crucial for advanced displays and lighting research. Suppressing detrimental energy migration near grain boundaries by studying single‐particle luminescence is an effective strategy to boost luminescence efficiency. Therefore, building upon conventional solid solution design, we are also committed to yielding better phosphors via coherent mixing of multiphase materials within a single particle. In this study, a discontinuous solid solution system ZnGa ₂ S ₄ : Eu ²⁺ —BaGa ₂ S ₄ : Eu ²⁺ is synthesized and reported, featuring tunable and efficient green luminescence. By enhancing lattice rigidity, the internal/external quantum efficiency (IQE/EQE) of single particle solid solution phosphor Zn _0.2 Ba _0.7 Eu _0.1 Ga ₂ S ₄ reaches 80.1%/61.4% (λ _ex = 400 nm), rivaling commercial green phosphors such as β ‐Sialon: Eu ²⁺ and SrGa ₂ S ₄ : Eu ²⁺ . More importantly, benefiting from the low‐density defects from coherent phase mixing, the single particle mixed‐phase phosphor (Zn _0.4 Ba _0.5 Eu _0.1 Ga ₂ S ₄ ) achieves further brightness enhancement (15–43%) compared to the single‐component solid solution phosphors under 450 nm excitation. This work not only presents a highly efficient green phosphor for high‐quality displays and full‐spectrum healthy lighting, but also offers a novel single particle mixed‐phase design strategy for developing highly efficient phosphors.