Highly efficient and zero-thermal-quenching blue-emitting Eu2+-activated K-beta-alumina phosphors

Discovery of highly efficient and thermal stable phosphors is a major topic in phosphor-converted white light-emitting diodes (LEDs). A highly efficient and zero-thermal quenching blue-emitting phosphor is realized in nominal Km-0.4Al11O17+δ:0.2Eu2+, which benefits from rigid aluminate structure with space group P63/mmc and the introduction of trap energy levels. The internal and external quantum efficiencies of optimal nominal K1.6Al11O17+δ:0.2Eu2+ are 97.1% and 61.8%, respectively. The phosphor exhibits zero-thermal-quenching behavior within 150 °C. Further increasing K content results in even better thermal stability, however, lower quantum efficiency. The relationship between luminescence properties and crystal structure was discussed. Results suggest that the blue-emitting phosphor is a candidate for white phosphor-converted LEDs based on near-UV or violet chip.