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|Title: ||Doped zirconia up-conversion phosphor and its acrylate nanocomposite|
|Keywords: ||氧化鋯上轉換螢光劑;氧化鋯奈米複合材料;zirconia phosphor;zirconia nano-composite|
|Issue Date: ||2015-09-23 10:44:05 (UTC+8)|
|Abstract: ||本研究分為氧化鋯與壓克力之奈米複合材料研發與奈米升頻螢光劑合成與應用兩部分。我們首先在低溫強鹼環境下製備約6 nm之氧化鋯立方晶粒子，接著依序以醋酸與-carboxyethyl acrylate進行表面修飾。根據熱重與液態核磁共振分析推算，每奈米平方表面分別接枝了1.3個醋酸與2.5個 -carboxyethyl acrylate。經雙重修飾的粒子可透明分散至醚酯類與非極性溶劑中，並可混合至商用壓克力單體中(OPPA)得到透明膠體。將此膠體塗佈於玻璃基板硬化後，可製作出透明度大於95%且折射率約1.74的透明連續膜。|
我們又在合成時添加稀土元素製備出約6 nm摻雜稀土氧化鋯粒子。清洗後鍛燒至900oC。獲得具升頻效果之奈米螢光劑。並以ICP、PL、XRD和TEM分析稀土元素濃度、清洗方式與鍛燒溫度對升頻轉換之影響。結果顯示稀土元素的摻雜量與晶相的穩定成正比關係。當Er2O3/Yb2O3/Y2O3莫耳參雜量等於1.2/5.8/3.7且經900oC鍛燒者，其升頻轉換的效率最高。以980 nm入射光產生的升頻螢光可分為紅光(650 nm)與綠光(544 nm)。鍛燒至700oC的樣品，其紅綠光的比例會隨Er2O3/Yb2O3摻雜比例增加而增加。然而鍛燒至900oC的樣品，其紅綠光的比例固定，不隨Er2O3/Yb2O3比例改變。此螢光劑在波長354 nm之紫外線激發下，亦會放射出由350 nm跨越至650 nm的寬頻螢光。最後我們嘗試將此螢光劑混入染料敏化太陽能電池所用之散射層中並與常規之太陽能電池比較。雖然原先預期可將紅外線轉換成可見光並反射，以增加光源之利用。但是實際測量發現反射層中奈米螢光劑參雜的越多，其太陽能電池的效率卻越差。
;This study is on the preparation and application of zirconia/acrylate nanocomposite and lanthanide doped nano-zirconia as up-conversion phosphor.
Cubic zirconia nanoparticles (~6nm) have been prepared at high concentration under strong alkaline (pH: ~12) and low temperature (110oC) conditions. Their surface was subsequently modified with acetic acid and β-carboxyethyl acrylate to enable the dispersion in solvents comparable to acrylic resin. Accordant to TGA and 1H NMR analysis, there were 1.3 and 2.5 molecules of acetic acid and β-carboxyethyl acrylate, respectively, bonded on each nm2 of zirconia surface. The dual ligand modified zirconia nanoparticle could be dispersed into ester ether or similar hydrophobic solvents. The clear sol obtained can then be blended with a high refractive index acrylic monomer (OPPA), and coated onto a substrate. A transparent and non-crack film, with ~1.74 index and above 95% transmittance, could be prepared. This would be useful in the manufacture of brightness enhancement film or optical lens.
The same synthesis process could be extended to the preparation of lanthanide doped zirconia. A nano-size up-conversion phosphor was obtained after proper rinsing and calcination. ICP, XRD, TEM and PL were employed to characterize its composition, crystalline phase and size, as well as its up-conversion efficiency. It was found that the addition of lanthanide helped to stabilize the cubic crystalline phase. The highest up-conversion efficiency achieved was the one doped with 1.2/5.8/3.7 mol% of Er2O3/Yb2O3/Y2O3 and subjected to 900oC calcination. It emitted red (650nm) and green (544nm) lights under the excitation of 980nm NIR. A broad emission range from 350 to 650nm could be observed when pumped by 354nm UV light. Finally, we tried to incorporate it into the scattering layer of a DSSC with the hope to extend the effective wavelength range of solar conversion. The phosphor included scattering layer did show a better reflectivity than the virgin one, but there was no improvement in the equivalent quantum efficiency. The overall efficiency of solar conversion actually decreased with the amount of phosphor incorporated. Therefore, our proposal on the use of nano-size up-conversion phosphor in DSSC was disproved.
|Appears in Collections:||[化學工程與材料工程研究所] 博碩士論文|
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