High thermal stability of high-power phosphor based white-light-emitting diodes employing Ce:YAG-doped glass

High thermal stability of high-power phosphor-converted white-light-emitting diodes (PC-WLEDs) incorporating a Ce:YAG-doped glass as the phosphor layer is demonstrated. An exploring study of lumen loss, chromaticity shift, and transmittance loss of high-power PC-WLEDs with Ce:YAG-doped glass and Ce:YAG-doped silicone under thermal aging at 150°C for 500 hours was performed and compared. The results showed that the high-power PC-WLEDs with 6 wt% of Ce:YAG-doped glass exhibited 60% less lumen loss, 50% lower chromaticity (CIE) shift, and 20% smaller transmittance loss than with the Ce:YAG-doped silicone. This clearly indicates that the Ce:YAG-doped glass exhibits higher thermal stability than the Ce:YAG-doped silicone after thermal aging. A better thermal stability of glass phosphor layer may be beneficial to the many applications where the LEDs with high-power and high reliability are demanded.