Tunable YAG:Ce3+ ceramic phosphors for white laser-diode lighting in transmissive/reflective models

Abstract

Y3Al5O12:Ce3+ (YAG:Ce3+) transparent ceramic phosphor (TCP) is one of the most promising converters for the laser-diode (LD) lighting because it has good capacity for absorbing blue light and prominent luminous efficiency (LE). A challenge is how to achieve a high-quality YAG:Ce3+ TCP to realize a high LE value. We propose a strategy to depress the defects by using the charge-balanced Mg2+-Si4+ to substitute the Al3+-Al3+. Benefiting from the flux effect of MgO and SiO2, the transmittance of the YAG:Ce3+ TCP (thickness of 1 mm) increases from 13 % to 70 % by controlling the pores in the TCP. By introducing Al2O3 to be one kind of light scatters to enhance the blue light absorption, the LE reaches 185.7 lm/W, which is much higher than the value (137 lm/W) of the same TCP previously reported. These results evidence that the optimized YAG:Ce3+ TCP has an excellent performance in LD lighting. Prototype white LD devices are demonstrated in both the transmissive and the reflective models.