Research On Preparation Of High-efficiency Multicolor Fluorescent Glass And Its Application In LED/LD

Solid-state lighting devices based on high-power white light-emitting diodes and laser diodes(WLEDs/WLDs)are regarded as the next-generation lighting source.The mainstream WLEDs/WLDs are constructed by blue LED/LD chips and a yellow-emitting YAG:Ce.Traditionally,YAG:Ce phosphor is mixed with organic resin,however,organic resin has a low thermal conductivity and is hard to dissipate heats generated from high-power excitation light sources,resulting in a low LE and a short service lifetime in WLEDs and even out of work in WLDs.Remote phosphor with a high thermal conductivity is an effective method to overcome the thermal effect in WLEDs/WLDs.The color rendering index(CRI)for WLDs based on YAG:Ce is about 70,which is far from the ideal value of CRI = 100.Because the yellow YAG:Ce lacks red components.Nitride red phosphors play a key role in enhancing color quality.However,nitride phosphors will be oxidized when they are prepared as an entire TCP/SCP/Pi G because of oxide raw materials and a high sintering temperature.Therefore,obtaining the ideal white light is still an urgent problem to be solved.The research content of this paper is divided into the following two parts:1.The multi-color Pi Gs are successfully fabricated by a single-step co-sintering strategy at a relative low temperature(850 °C),most of Pi Gs maintain a high internal quantum efficiency approaching 90 % of original phosphors.Under the 450 nm blue LD excitation,the luminous efficacy of YAG:Ce-Pi G reaches 239.3 lm/W,which is almost the best result in WLDs so far.2.The designed glass composition overcomes the oxidation,corrosion and decomposition of commercial nitride red phosphors,and achieves broadband emission of 500～700 nm by doping different proportions of red/yellow/green phosphors in the whole glass.In addition,a high-quality white light with a CRI of 94 was obtained.The co-mixing of a variety of phosphors provides a good strategy for obtaining ideal white light.