新穎稀土氟硫化物與氟硫氧化物螢光材料之製備、發光特性鑑定與其應用

Abstract

利用藍光或近紫外光晶片搭配螢光粉以產生白光的方法是目前白光發光二極體發展的主要課題之ㄧ。本論文主要以研發新型的氧氟硫化物和氟硫化物系列螢光體並研究其發光特性與潛在應用為重點。本研究利用固態反應於密閉石英管中，以 900 ~ 1000℃分別製備CeSF:Lnn+ (Lnn+ = Gd 3+ , Y 3+ , Tb 3+ , Mn2+ )、La3OF3S2:Ce3+ 氧氟硫化物螢光體與Ce2CaF4S2:Tb3+及(Ce1-xYx)2SrF4S2兩系列氟硫化物。粉末X光繞射、螢光光譜和掃瞄式電子顯微鏡被用以探討合成條件、活化劑摻雜濃度的最佳化，同時亦測量了激發與發光光譜、色度座標圖、量子效率與熱消光光譜，並進一步評估其應用於白光LED之潛力。 本研究首先探討不同主體之最佳製程條件與粉末X光繞射晶相之分析鑑定；第二部份則探討La3OF3S2:Ce3+、CeSF、Ce2CaF4S2與Ce2SrF4S2之發光特性；第三部份則探討摻雜Mn2+ 摻雜氟硫氧化物之發光特性；第四部份探討Ce3+/ Tb3+ 共摻氟硫化物螢光體之發光特性；最後則探討所合成螢光材料之熱消光效應。

White LEDs fabricated with blue or near-UV LED chips and compatible R/G/B phosphors is the main stream of current solid-state lighting device. This research is attempted to develop new fluorosulfide and oxyfluorosulfide phosphors undisclosed in the literature or patent application. We have prepared four series phosphors with compositions of CeSF:Lnn+ (Lnn+ = Gd3+, Y3+, Tb3+, Mn2+), La3OF3S2:Ce3+, Ce2CaF4S2:Tb3+ and (Ce1-xYx)2SrF4S2 by solid-state reactions in evacuated sealed quartz glass tubes at 900-1000℃, which were further characterized by powder X-ray diffraction, fluorescence spectroscopy, and electron microscopy to investigate their phase identity, luminescence, microstructures, chromaticity, quantum efficiency and thermal luminescence quenching behaviors. Based on the characterization results, we then evaluated their potential applications in fabrication of white light LEDs. This thesis first investigates the optimization of synthesis conditions and performs X-Ray diffraction characterization and phase identifications. The second part deals with the luminescence of La3OF3S2:Ce3+ and the third part investigates the luminescence of Mn2+-doped fluorosulfide and oxyfluorosulfide phosphors. Fourthly, this research investigates the luminescence of Ce3+/Tb3+-codoped fluorosulfides and studies the possibility of Ce3+ → Tb3+ energy transfer. Finally, we investigated the thermal luminescence quenching property of all synthesized phosphors and fabricated a white-light LED device using Ce2CaF4S2:Tb3+ and blue-emitting commodity phosphors in combination of a 365 nm near-UV LED chip.