Correlated Na+ Ion Migration Invokes Zero Thermal Quenching in a Sodium Superionic Conductor-type Phosphor

Among the many potential Eu 2+ -activated sodium superionic conductor (NASICON)-based host materials, the Sc 3+ -based NASICON phosphor (Na 3 Sc 2 (PO 4 ) 3:Eu 2+ ) is a promising phosphor material for high-power lighting applications owing to its unusual thermal stability at elevated temperatures. It has previously been shown that negative thermal quenching (TQ) can be tailored to zero TQ depending on the Eu 2+ concentration. However, the obtained zero-TQ composition has low photoluminescent quantum yields, which hinders its applicability to high-power lighting. Herein, we report a holistic study of the tuning of thermal stability from negative TQ to zero TQ while preserving the original emission efficiency by introducing Lu 3+ ions in Na 3 Sc 2 (PO 4 ) 3:Eu 2+ . Furthermore, we fabricated a high-power white light-emitting diode using optimized Lu 3+ -doped Na 3 Sc 2 (PO 4 ) 3:Eu 2+ as the blue component, delivering a high color-rendering index value of 90 with a high luminous efficiency value of 25 lm/W obtained at a flux current of 1000 mA. Therefore, the findings of this work provide novel scientific insights into the importance of structure–property relationships in designing highly efficient thermally stable phosphors for high-power lighting applications.