A new CaF2-YAG: Ce composite phosphor ceramic for high-power and high-color-rendering WLEDs

摘要

Thermally robust and optically transparent phosphor ceramics are now attracting great attention as promising luminescent materials for high-power white light-emitting diodes (WLEDs). Here, we report a new CaF2-YAG: Ce phosphor ceramic in which the yellow-emitting YAG: Ce particles are embedded in a non-luminescent CaF2 ceramic matrix. The composite phosphor ceramic was fabricated at a very low sintering temperature of 700 degrees C by using a simple hot-pressing method. No detectable interfacial reaction occurs between the YAG: Ce particle and the CaF2 matrix. Owing to the excellent optical properties and high thermal conductivity of CaF2, the prepared CaF2-YAG: Ce phosphor ceramic shows a high quantum efficiency (IQE = 83.2%), and a low thermal quenching (only 9% loss in luminescence at 150 degrees C). WLEDs, fabricated by combining the CaF2-YAG: Ce phosphor ceramic with a 460 nm blue chip of 2 W, exhibited bright white light with a luminous flux of 359.7 lm, a color temperature of 4021-7941 K and a color rendering index of 70.1-82.7. The composite phosphor ceramic showed a better performance than the traditional single-phase YAG: Ce ceramic, enabling it to be used in high-power WLEDs.