Luminous efficiency of open remote phosphor-converted white-light-emitting diodes

Phosphor-converted white-light-emitting diodes (WLEDs) were fabricated by using the open remote method, a new packaging technology, and their optical and electrical properties were compared with those of the devices fabricated by using the conventional slurry and the closed remote methods. The optimum amount of phosphors for the highest luminous efficiency in the slurry samples was found to be 6 wt% of phosphors. The value of the luminous efficiency of the closed remote samples was nearly equal to that of the slurry samples even though the amount of phosphors used in the closed remote sample was much less than that used in the slurry sample. The luminous efficiency of the open remote sample is also nearly equal to the luminous efficiencies of the slurry and the closed remote samples within 12%. However, the amount of phosphors used in the open remote sample was less than one-third the amount used in the slurry sample. This indicates that the amount of phosphors used for the fabrication of WLEDs can be greatly reduced by using the open remote method without losing luminous efficiency.