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

• Published in: Optics express 2012-04, Vol.20 (9), p.10218-10228
• Main Authors: Park, Hoo Keun, Oh, Ji Hye, Do, Young Rag
• Format: Article
• Language: English
• Subjects: Color; Equipment Design; Equipment Failure Analysis; Lighting - instrumentation; Semiconductors
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.20.010218

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.