真空紫外線激發螢光粉之設計、製備與發光特性鑑定

Abstract

由於環保意識日益抬頭，近年來綠色光源與顯示逐漸受產學界的注目。所謂的「綠色」係泛指元件不含有毒物質，目前做法係以鈍氣(如氙)以取代傳統的汞作為激發光源材料。由於氙氣受激發後形成電漿態所放射真空紫外光波段波長為147 nm與172 nm之輻射，因此探討與研發新穎可供真空紫外光激發螢光體實有迫切必要。 本論文利用同步輻射真空紫外光源與自有的真空紫外螢光光學參數測量系統深入研究紅光(A,B,RE)(C,D)O4、綠光(E,F)2(G,H)O4、綠光(Zn,Mn)B6O13與綠光Ca(La,Gd,Tb)4Si3O13等四種螢光體的製程、X光繞射晶相鑑定、激發與發光光譜、狀態密度 (DOS)函數理論計算及色度座標。此外市售螢光粉商品之各項發光特性經實測作為技術指標，本論文藉由光譜與理論計算相互呼應，螢光體激發光譜之吸收大多被清楚標示，此項成果將對真空紫外光譜的深入了解提供極大助益。 除上述四種螢光材料的特性已完整被探討之外，另Li2(Sr,Eu)SiO4、(Sr,Eu)3MgSi2O8、(Sr,Eu)8Si4O12Cl8、(Ca,Eu)2PO4Cl、KCa(Gd,Tb)(PO4)2、Ca4(Gd,Eu)O(BO3)3、Na(Y,Eu)GeO4、(Ca,Ln)3(PO4)2 (Ln = Tm3+/Ce3+)與(Mg,Mn)2SnO4等九種螢光體之製程、發光特性與色座標等性質，本研究僅初步探討。其中部分螢光體之主體雖然在真空紫外光波段呈現良好吸收，但主體→發光中心能量傳遞效率不高，影響該螢光體發光效率；另一部分則雖呈現高效率放光強度，但其發光波長偏向紫外光，因此應用潛力不高。 本論文除探討上述十三種可供真空紫外線激發螢光體發光與材料特性之外，並試圖提出未來開發新穎真空紫外光螢光體主體與發光中心篩選時可供參考的通則，以提供之指引。

Since eco-awareness has been an issue seriously concerned by the world in recent years, green materials and technology for lightings and display have attracted keen attentions from both academics and industries. The meaning of so-called green generally refers to materials or technologies without using toxic materials such as mercury. Nowadays, academics and industries have tried to use xenon gas to replace mercury as the excitation source. Xenon in the plasma state emits light at 147 nm and 172 nm in wavelength after being excited, which are classified in the vacuum ultraviolet (VUV) spectral range, and, therefore, it is urgently demanded to develop phosphors for VUV excitation. In the first part, this dissertation discusses in detail the luminescence properties of the following four phosphors (A,B,RE)(C,D)O4, (E,F)2(G,H)O4, (Zn,Mn)B6O13 and Ca(La,Gd,Tb)4Si3O13. With the aid of vacuum ultraviolet (VUV) light source at National Synchrotron Radiation Center and plasma display panel (PDP) optical parameters testing system in our group at NCTU, we have carried out the X-ray diffraction (XRD) analysis for phase identification, photoluminescence (PL) spectrum measurements, calculations of density of state (DOS), and the determination of chromaticities, with the performance of selected commodity phosphors used as technical benchmarks for comparison. Additionally, this dissertation studies and labels absorption peaks in each VUV excitation spectra by comparing and analyzing the PL spectra and the results of DOS. This can bedstead to understand the absorption peaks in the VUV region for future researchers. Besides the four types of phosphor discussed above, this dissertation also investigates primarily the materials properties, including the synthesis, luminescence, and chromaticity of additional nine phosphors, namely, Li2(Sr,Eu)SiO4, (Sr,Eu)3MgSi2O8, (Sr,Eu)8Si4O12Cl8, (Ca,Eu)2PO4Cl, KCa(Gd,Tb)(PO4)2, Ca4(Gd,Eu)O(BO3)3,Na(Y,Eu)GeO4, (Ca,Ln)3(PO4)2 (Ln = Tm3+/Ce3+), and (Mg,Mn)2SnO4. Some of these phosphors exhibit low luminescence efficiency due to inefficient energy transfer from the hosts to the activators, even though the hosts have good absorption in the VUV spectral region; some of the rest emit efficiently but the emission wavelength is too short to be used in practical applications. The conclusion of this dissertation not only sums up the properties of thirteen RGB phosphors with a variety of chemical compositions and luminescence performance, but also advances some guidelines and principles to be consulted when designing and synthesizing new vacuum ultraviolet phosphors.