High-Temperature (350°C) Glass Phosphor Layer for Converted White Light-Emitting Diodes

The high-temperature operation up to 350 degrees C. of glass phosphor layer for using in converted white light-emitting diodes is demonstrated. The results showed that the phosphor-converted white light-emitting diode (PC-WLEDs) maintained good thermal stability in lumen, chromaticity, and transmittance characteristics at the high temperature up to 350 degrees C. The lumen degradation, chromaticity shift, and transmittance loss in glass based high-power PC-WLEDs under thermal aging at 150, 250, 350, and 450 degrees C. are presented and compared with the silicone based high-power PC-WLEDs under thermal aging at 150 and 250 degrees C. The result clearly indicated 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 doped encapsulation in high temperature PC-WLEDs could be arisen from the material property of glass transition temperature 567 degrees C higher than silicone of 150 degrees C. These newly developed high-temperature glass based PC-WLEDs are 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.