全無機型鈣鈦礦量子點之合成及穩定性提升鑑定與其在白光發光二極體之應用

發光二極體(LED)是近幾年迅速崛起的固態發光元件，由於其擁有照明壽命長、節省電力、熱耗損等優點而被廣泛應用於顯示器及照明設備上，但普遍使用藍光晶片搭配螢光粉材料皆存在半高寬過寬與色純度不高且色域面積小等問題，因此無法實現高品質之背光顯示器與照明設備的目標，故開發具有窄的半高寬之量子點技術以提升發光元件的色彩飽和度。本論文第一部分為選用膠體溶液化學合成法合成全無機型鈣鈦礦量子點CsPbX3 (X = Cl, Br, I)結構，並分析其發光性質與特性鑑定，其具有立方晶系的晶體結構與良好的結晶性，並且可藉由調控鹵素陰離子比例組成以控制其發光波長可涵蓋整個可見光範圍，具有高量子效率、窄的放光波長、高色純度等優點。為了提升鈣鈦礦量子點之穩定性與抵制陰離子交換反應發生，因此選擇疏水性多孔二氧化矽氣凝膠對其進行包覆，並對其作放光性質、晶體結構鑑定與穩定性、陰離子交換反應等測試，研究成果顯示疏水性多孔二氧化矽氣凝膠包覆鈣鈦礦量子點CsPbBr3可以成功提升量子點對水氣與空氣的穩定性與降低陰離子交換反應的發生。最後將其應用於白光發光二極體(W-LED)，搭配藍光晶片(450 nm)與紅光螢光粉(K2SiF6:Mn4+)成功封裝出CIE1931色度座標(0.3856, 0.3331)，CCT (3444K)之W-LED，期望能達到高色彩飽和度之目標。第二部分為以CsPbBr3之衍生物的Cs4PbBr6作為保護CsPbBr3量子點之六方晶系結構，期望以提升CsPbBr3量子點之穩定性，並對其進行放光性質、晶體結構鑑定與穩定性等測試，透過XRD與HRTEM可以證明Cs4PbBr6的結構中存在CsPbBr3量子點，而Cs4PbBr6之結構確實能提升CsPbBr3量子點因環境因素影響而發生結構降解而導致發光淬滅。本實驗結果顯示疏水性多孔二氧化矽氣凝膠可以有效提升鈣鈦礦量子點的穩定性與降低陰離子交換反應，此成果對未來應用於發光元件有很大的幫助。

關鍵字

鈣鈦礦；量子點；發光二極體

並列摘要

In recent years, white light-emitting diodes (W-LEDs) has drawn attention due to their high brightness, environmentally friendly, long lifetime, high energy efficiency, and less power consumption. Therefore, it is considered as the next generation light source. However, there have some problems for the phosphors used in LED, such as a broad width FWHM, low color purity and narrow color gamut area. Therefore, we need to develop a narrow FWHM quantum dot to enhance the color purity of the light-emitting diodes. In this study, all-inorganic CsPbX3 (X=Cl, Br, I) perovskite quantum dots were synthesized via chemical colloidal synthesis and hot-injection method. Perovskite quantum dots are highly recognized due to their high photoluminescence properties, narrow lines and tunable wavelength; however, they are also known to have high sensitivity to moisture which leads to poor stability and unwanted anion exchange reactions. In order to resolve this, this study involves encapsulating CsPbBr3 with hydrophobic surface-modified mesoporous silica aerogel (CsPbBr3/PMSQ AG). This unique approach can not only enhance the stability of CsPbBr3 against moisture but also prevents anion exchange reactions. Water stability tests demonstrate that the as-synthesized CsPbBr3/PMSQ AG composites retained half of its initial intensity after soaking in water for more than 14 days. Then, packaged white light LED was obtained by combining green-emitting CsPbBr3/PMSQ AG and red-emitting K2SiF6:Mn4+ phosphor, and depositing onto a blue-emitting GaN-LED chip. Also, Cs4PbBr6 which a derivative of CsPbBr3 was also studied. Cs4PbBr6 is a hexagonal structure of Cs4PbBr6 which can act as a protective barrier for CsPbBr3 quantum dots. Hence, Cs4PbBr6 can further improve the stability of CsPbBr3 and enhance its performance to further provide a better application for white light LEDs.