Abstract
A glass phosphor layer with ultra-high thermal stability appropriate for
phosphor-converted white light-emitting diodes (PC-WLEDs) is demonstrated. The results
showed PC-WLEDs utilizing the high thermal stable glass phosphor maintained good thermal
stability in lumen, chromaticity, and transmittance characteristics under the thermal
aging condition up to 350 °C. This is a considerable high operating
temperature for a phosphor layer in the PC-WLEDs. The lumen degradation, chromaticity
shift, and transmittance loss in the glass-based PC-WLEDs under thermal aging at 150
°C, 250 °C, 350 °C, and 450
°C are also presented and compared with those of silicone-based
PC-WLEDs under thermal aging at 150 °Cand 250 °C.
The result clearly demonstrated that the glass-based PC-WLEDs exhibited better thermal
stability in lumen degradation, chromaticity shift, and transmittance loss than the
silicone-based PC-WLEDs. The advantages of glass encapsulation in high-temperature
operation of the PC-WLEDs could be explained that the glass transition temperature of
the glass phosphor (567 °C) was much higher than it of silicone (150
°C). The newly developed ultra-high thermal-stable glass is
essentially critical to the application of LED modules in the area where the high-power,
high-temperature and absolute reliability are required for use in the next-generation
solid-state lighting.
© 2013 IEEE
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