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  • Toward scatter-free phosphors in white phosphor-converted light-emitting diodes.

Toward scatter-free phosphors in white phosphor-converted light-emitting diodes.

Optics express (2012-04-27)
Hoo Keun Park, Ji Hye Oh, Young Rag Do
ABSTRACT

Scatter-free phosphors promise to suppress the scattering loss of conventional micro-size powder phosphors in white phosphor-converted light-emitting diodes (pc-LEDs). Large micro-size cube phosphors (~100 μm) are newly designed and prepared as scatter-free phosphors, combining the two scatter-free conditions of particles based on Mie's scattering theory; the grain size or grain boundary was smaller than 50 nm and the particle size was larger than 30 μm. A careful evaluation of the conversion efficiency and packaging efficiency of the large micro-size cube phosphor-based white pc-LED demonstrated that large micro-size cube phosphors are an outstanding potential candidate for scatter-free phosphors in white pc-LEDs. The luminous efficacy and packaging efficiency of the Y(3)Al(5)O(12):Ce(3+) large micro-size cube phosphor-based pc-LEDs were 123.0 lm/W and 0.87 at 4300 K under 300 mA, which are 17% and 34% higher than those of commercial powder phosphor-based white LEDs (104.8 lm/W and 0.65), respectively. In addition, the introduction of large micro-size cube phosphors can reduce the wide variation in optical properties as a function of both the ambient temperature and applied current compared with those of conventional powder phosphor-based white LEDs.

MATERIALS
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Sigma-Aldrich
Yttrium aluminum oxide, nanopowder, <150 nm particle size (TEM), 99% trace metals basis