High thermal stability and humidity resistance of phosphor-converted white-light-emitting diodes (PC-WLEDs) using Ce:YAG doped glass, instead of conventional Ce:YAG doped silicone, as a phosphor-converted layer is proposed and fabricated. The glass has five times higher glass transition temperature (Tg) of 750¢J compare with silicone of 150¢J, that could exhibited better performance than silicone, including lumen loss, chromaticity shift, transmittance loss, and peak emission intensity undergoing three industry-standard reliability tests at either high (8wt%) or low (2wt%) doping concentrations of Ce:YAG. The proposed glass phosphor possesses host stability as glass and retains desired fluorescence as Ce:YAG.
In thermal aging, thermal shock, and damp heat reliability results, the thermal aging has the largest degradation of lumen loss, but the results showed better thermal stability that the glass phosphor with 22~30% lumen loss improvement for 2~8 wt% Ce:YAG doping than silicone phosphor. The damp heat test has the largest degradation of chromaticity shift, but the results showed excellent humidity resistance that the glass phosphor with highest 49~65% chromaticity shift improvement for 2~8 wt% Ce:YAG doping than silicone phosphor. But under thermal shock test, there isn¡¦t a large difference between glass and silicone phosphor. In this study, we demonstrate the feasibility of adapting glass as a phosphor-converted layer in PC-WLED module that can potentially provide higher reliability and better performance for high-power LEDs, particularly in the area where strict reliability is highly required and in the environment where silicone does not stand for long.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0720110-001152 |
| Date | 20 July 2010 |
| Creators | Chung, Cheng-hsun |
| Contributors | Jao-Hwa Kuang, Wood-Hi Cheng, Jimmy Wang, Ray-Hua Horng, Jiang-Jen Lin |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0720110-001152 |
| Rights | campus_withheld, Copyright information available at source archive |
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