Facile fabrication of Eu~(3+) activated YAG:Ce~(3+) glass ceramics exhibiting high thermal stability and tunable luminescence for warm white LEDs

摘要

To relieve the issues of high correlated color temperature and low color rendering index, it is urgent to develop an inorganic color converter materials with both red- and yellow-emission to replace the conventional organic resin/silicon-based color converter and acquire warm white light-emitting diodes (WLEDs). In our work, transparent glass-ceramics (GCs) containing Ce~(3+):Y_3Al_5O_(12) (Ce~(3+):YAG) yellow phosphors and Eu~(3+) ions are successfully fabricated by using low temperature co-sintering technique. And then the microstructure and luminescence properties of the GC are investigated in detail. Importantly, the impact of Ce~(3+):YAG phosphors concentration, Eu~(3+) ions concentration, co-sintering time and the GC thickness on optical performances are also systematically demonstrated. Impressively, the as-fabricated samples exhibit an efficient red emission at 611 nm owing to the ~5D_0→~7F_2 transition of Eu~(3+). Subsequently, the temperature-dependent luminescence and thermal quenching is also investigated. Finally, the constructed WLEDs show an optimal luminous efficacy of 120.85 lm/W, a color rendering index of 70.2 and a correlated color temperature of 5267 K. All the results indicate that the as-fabricated GC would have potential practical applications in high-power WLEDs.