請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/16388
標題: | 應用於發光二極體之氮化物螢光發光材料 Nitridosilicates Phosphors for Application in Light-emitting Diodes |
作者: | Chiao-Wen Yeh 葉巧雯 |
指導教授: | 劉如熹 |
關鍵字: | 氮化物,螢光粉,發光二極體, Nitridosilicate,Phosphor,Light-emitting diode, |
出版年 : | 2012 |
學位: | 博士 |
摘要: | 氮化物發光材料為近年來新開發出之適合白光LED應用高效螢光粉,其乃利用稀土元素作為活化中心摻雜。氮化物發光材料之研製與開發亦促進白光發光二極體(light-emitting diodes; LED)技術迅速發展。白光LED做為照明使用氮化物與氮氧化物,可提高演色性與化學穩定性,因其具有較緊密之共價結構,且由於晶場分裂理論,氮化物比氧化物能得到更紅位移之放光,藉此使得白光發光光譜更趨近自然光,反映真實色彩。
本實驗研究以氮化物及氮氧化物螢光粉為主,討論目前螢光粉體所遭受之問題,並嘗試解決問題及探討其機制。非稀土摻雜之藍色氮化物(SrSi6N8)螢光粉以固態高壓合成法合成,其放射光譜452 nm之能量約為2.75eV,其乃因矽原子之電子4s至3p軌域躍遷,同系統摻雜少量氧後(SrSi6N7.95O0.05),則除了452 nm放光外,亦產生以氧取代氮缺陷上之氧原子之電子3s至2p軌域躍遷。此研究有助於解決稀土昂貴,不易回收之缺點。於Sr2-xSi5N8:Eux之實驗中,揭露了昔知紅色氮化物螢光粉之熱淬滅不可回復性,利用同步輻射光源近場X光繞射解析結構,並透過電子穿隧顯微鏡發現其表面非晶化之現象,藉由銪原子價數探討其機制。綠色螢光粉SrSi2O2N2:Eu藉由Mn原子共摻雜,其利用螢光時間延長,使得其可應用於交流LED上,有效減低閃爍問題,並利用熱釋光譜法探討結構鍵結環境。 本研究之特色為著重於利用氮化物及氮氧化物解決目前應用層面之問題,此研究深入探討氮氧物與氮氧化物螢光粉特性及機制,故極具學術及應用價值。 Rare-earth doped nitridosilicates and oxonitridosilicates phosphors applications for light-emitting diodes (LEDs) have been the object of study in recent years. The phosphors are attractive converter materials for white LEDs applications due to their efficient luminescent characteristics. Furthermore, the thermal and chemical stabilities materials have gathered great importance. The purpose of this study was to address the important problems and to find out the answer for the phenomenon which has never been discussed. This research involved identification methods, measurement of luminescent properties, morphology techniques, fine structure identification X-ray absorption spectroscopy and computational method to predict the mechanism. First, the non-rare-earth nitridosilicate phosphors (SrSi6N8) were successful synthesized from a solid state reaction by gas-pressure sintering method. This phenomenon is predicted using the calculated 2.75 eV (452 nm) energy gap between the 3p-orbitals and the 4s-orbitals of Si, which is consistent with the main peak associated with the emission band and the O-replacement defect system (SrSi6N7.95O0.05) from a separation of 1.98 eV (625 nm) for the energy gap between the 3s-orbitals and the 2p-orbitals of O. The thermal degradation in Sr2-xSi5N8:Eux is due to the formation of the amorphous phase on the surface during oxidative heating treatment which result in by the oxidation of Eu ions from divalent to trivalent and less covalence of the compounds. Last, the SrSi2O2N2 doped with Eu2+ and Mn2+ was investigated by thermoluminescence because the time gap is closely related to the scintillation phenomenon of AC LED. In this study, we focus the nitridosilicate and oxonitridosilicate phosphors to explain the detail with their unique feature. We hope through these researches to extend more nitride materials topics. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/16388 |
全文授權: | 未授權 |
顯示於系所單位: | 化學系 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-101-1.pdf 目前未授權公開取用 | 9.23 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。