Suppressed concentration quenching and tunable photoluminescence in Eu 2+ -activated Rb 3 Y(PO 4 ) 2 phosphors for full-spectrum lighting.

Highly efficient inorganic phosphors are desirable for lighting-emitting diode light sources, and increasing the doping concentration of activators is a common approach for enhancing the photoluminescence quantum yield (PLQY). However, the constraint of concentration quenching poses a great challenge for improving the PLQY. Herein, we propose a fundamental design principle by separating activators and prolonging their distance in Eu 2+ -activated Rb 3 Y(PO 4 ) 2 phosphors to inhibit concentration quenching, in which different quenching rates are controlled by the Eu distribution at various crystallographic sites. The blue-violet-emitting Rb 3 Y(PO 4 ) 2 :xEu (x = 0.1%-15%) phosphors, with the occupation of Rb1, Rb2 and Y sites by Eu 2+ , exhibit rapid luminescence quenching with optimum external PLQY of 10% due to multi-channel energy migration. Interestingly, as the Eu concentration increases above 20%, Eu 2+ prefer to occupy the Rb1 and Y sites with separated polyhedra and large interionic distances, resulting in green emission with suppressed concentration quenching, achieving an improved external PLQY of 41%. Our study provides a unique design perspective for elevating the efficiency of Eu 2+ -activated phosphors toward high-performance inorganic luminescent materials for full-spectrum lighting.