Site-selective occupation of Eu3+, high-quenching concentration, and enhanced luminescence via Mg2+ co-doping in a borophosphate phosphor

Abstract

Eu3+-activated red-emitting materials can significantly enhance the chromatic properties of white light-emitting diodes (w-LEDs). Unfortunately, to keep away from luminescence quenching, the dopant Eu3+ concentration usually holds at a low level. This also brings about the low luminescence efficiency of Eu3+-activated phosphors. In this work, the high-quenching concentration of Eu3+ is acquired in KNa4B2P3O13 (KNBP) due to the host structure-caused suppression on the concentration quenching. The site-selective Eu3+ occupancy is revealed according to the DFT calculations and structural analysis. Moreover, the Mg2+ concentration-dependent charge compensation effect is investigated in detail. As a representative KNBP:30%Eu3+,1%Mg2+ phosphor, the luminescent intensity is increased 3.87-fold as compared to KNPB:30%Eu3+. The internal quantum efficiency (IQE) is enhanced from 42.8 to 63.4%. Meanwhile, it displays excellent thermal stability (89%@423 K). Finally, a w-LEDs device with excellent color quality (CCT = 4523 K and Ra = 90.5) was encapsulated using KNBP:30%Eu3+,1%Mg2+. This work promotes the understanding of the host structure-caused concentration quenching delay and illustrates an alkaline earth charge compensation pathway.