Date
Place
- Room H (Room Hall 1, 1F)
- P1. Poster Session I
- August 20, 2015 (Thursday)
- 14:00 ~ 15:30
- [P1-113]
- 14:00 ~ 15:30
- Title:Yellow YAG:Ce Single Crystal Phosphor with High Thermal Stability for High-Power White Light Source
- Taewook Kang, Heelack Choi (Pukyong Nat'l Univ., Korea), Youngsic Kim, Sunghoon Lee, Jeonggon Ryu (Hyosung Corp., Korea), Jaehyoung Park, Seokkyu Lim, and Jongsu Kim (Pukyong Nat'l Univ., Korea)
Abstract: For high-power light-emitting diode(LEDs) or laser diodes (LD) (> 1 watt per a single package), the conventional structure with yellow phosphor powders dispersed in the organic epoxy resin exhibit a significant drop in efficiency at high blue irradiations and high temperatures (100 ¡É ~ 150 ¡É). It is due to burning of organic epoxy resin as well as blackening of phosphor surface. The yttrium aluminum garnet (Y3-xAl5O12?:Xce3+, YAG) has the excellent thermal conductivity (~ 10 W/m¡¤K) compared with other silicate phosphors (~ 1.5 W/m¡¤K). The high thermal conductivity prevents local heating from a concentrated high-power blue irradiation and provide a good lumen maintenance at a high temperature, and thus a long lifetime is expected. Thus a single crystal YAG phosphor is suggested as an alternative to phosphor for high-power lighting source Consequently we have studied YAG:Ce single crystal phosphor. Yellow-emission YAG single crystal phosphor was grown through a floating zone method. It showed a broader blue excitation and yellow emission spectra with much higher thermal quenching ratio at 200 ¡É of about 92 % due to the f-d transition of Ce3+ ion than the conventional powder as seen in Fig. 1. The single crystal as a color conversion material was pumped by a blue laser diode with optical power of 5 watt , and thus high-power white light with color temperature of 5000 K was generated .
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