Ce,Tb,Gd:YAG-Al2O3 eutectic crystal phosphor plates for high-power warm white LED applications

Abstract

Ce,Tb,Gd:YAG-Al2O3 eutectic crystal phosphor plates (ECPPs) were grown by the micro-pulling-down (μ-PD) method to adjust correlated color temperature (CCT) and color rendering index (Ra) for high-power warm white LED applications. Tb3+ and Gd3+ ions in Ce:YAG-Al2O3 play a positive role in spectra adjustment based on the structural and luminescent properties investigations. Tb3+ ions enhance the fluorescence lifetime of Ce3+ ions from 61.1 to 63.8 ns and improve the luminescence efficiency, and the highest optical-optical conversion efficiency (OCE) is 270.56 lm/W. Corresponding luminescence shift from cold white to greenish yellow. Gd3+ ions increase the peak wavelength from 554 to 564 nm and improve the Ra value, and the maximum Ra is 75.5. Corresponding luminescence is shifted from cold white to reddish violet. In addition, the luminescence of Ce,Tb,Gd:YAG-Al2O3 ECPPs is adjusted to warm white with CIE coordinate (0.374, 0.364) and CCT of 4102 K, and Ra of 73.0, which is of great significance for realizing the high-power warm white LED lighting.