Luminescence-Tunable High-Power White Light-Emitting Diodes Through Dam-Adjusted Ceramic Substrate

In this work, luminescence-tunable high-power white light-emitting diodes (WLEDs) were fabricated by printing phosphor-in-silicone on 3-D ceramic substrates with adjusted dam structure. The 3-D ceramic substrate was prepared by a simple and efficient magnetic field-oriented grouting method in which silicate ceramic dam with adjusted height and angle was reliably bonded on a planar direct plating ceramic (DPC) substrate. The phosphor concentration of WLEDs was optimized to realize white light. At the phosphor concentration of 12 wt%, the packaged WLEDs achieve cool white light and high optical consistency. The influence of dam height and angle on the optothermal performances of WLEDs was investigated. As the dam height increases from 0.5 to 1.0 mm, the luminous efficiency (LE) of WLEDs first increases and then decreases, and the correlated color temperature (CCT) gradually decreases. At the dam height of 0.7 mm, the WLED achieves a high LE of 122 lm/W and a suitable CCT of 5008 K. Furthermore, the LE increases from 122 to 132 lm/W and the CCT decreases from 5006 to 4458 K when the dam angle changes from 0° to 40°. Importantly, the dam height and angle have no obvious influence on the surface temperature of WLEDs, and the WLEDs still display a low surface temperature even at high input current due to the effective heat dissipation of dam structure. The results indicate that the fabricated WLEDs achieve the tunable luminescence and low working temperature, which can be treated as an efficient and reliable high-power white source.