無機鈣鈦礦量子點之合成、特性分析與應用

Abstract

發光二極體之環保節能特點汰換白熾燈等傳統光源，應用範圍廣泛包含照明、背光顯示器與行動裝置等，被喻為二十一世紀最受矚目之技術。其中，智慧生活開展導致背光顯示器需求越益龐大，而普遍使用螢光粉材料皆存在半高寬過寬、色純度不高且色域面積小之問題，因此無法發展高品質之背光顯示器，故窄半高寬譜帶之量子點技術被視為新一波高色彩飽和度顯示器革命。 為開發適合用於背光顯示器之發光材料，選用膠體溶液化學法合成全無機式鈣鈦礦量子點CsPbX3 (X = Cl, Br, I )結構。藉Bruker D2 phaser與同步輻射中心之01C2實驗站，量測X光粉末繞射圖譜，並以TOPAS進行結構精算，由結果可知不同比例鹵素組成皆屬立方晶系之純相。亦透過同步輻射中心之17C1光束線收集X光近邊緣吸收結構數據，首次解析出鈣鈦礦量子點中鉛離子之氧化價數。再以場發射電子顯微鏡分析量子點之形貌為立方結構，且隨著鹵素組成變化對應晶面間距亦存有規律性。接著利用Tauc plot方法計算能隙數值，證實鈣鈦礦量子點因改變Br/I比例造成放光性質迥異之主要因素為Br與I離子其原本之能隙差異，而非顆粒大小造成之放光位移。此外，亦調控鈣鈦礦不同Br/I比例以探討放光波長變化趨勢，結果顯示等量改變之Br/I比例其放光呈對稱性分佈，配合精算結果得知隨I等比例增加及Br等比例減少將造成晶體膨脹，此趨勢影響CsPb(Br1-xIx)3之放光特性導致於特定區間放光位置相距甚遠，並呼應上述計算之能隙數值。故晶體結構膨脹、放光位置間隔與能隙數值差異為環環相扣關係。 本研究揭露全新藍、綠與紅色鈣鈦礦量子點之多孔洞二氧化矽奈米複合材料技術，有效避免離子交換問題，且提升材料之熱穩定性與光穩定性。並將此技術首次應用於白光發光二極體封裝，以NTSC與Rec. 2020標準計算封裝數據之色域覆蓋率分別達110%及80%以上，較傳統螢光粉高出甚多，代表使用鈣鈦礦量子點材料更符合現今廣色域背光顯示目標，凸顯量子點材料之重要與突破性。

The thrust of my master thesis is on the synthesis of zero-dimension all-inorganic perovskite quantum dots(CsPbX3, X = Cl, Br, I) nanomaterials by colloidal solution methodas luminescent materials for light emitting diode(LED)backlight display applications. In this study, we tuned halogen composition ratio and investigated particle size and band gap difference to explain the spectral shift. We expect to find a correlation of the spectral shift and therefore establish a general explain. We also controlled the Br/I ratio of CsPb(Br1-xIx)3 and analyzed their different optical properties. First, the 01C2 experiment station at the Synchrotron Radiation Research Center and Bruker D2 Phaser were used to measure X-ray powder diffraction patterns. We employed field emission electron microscopy to analyze the morphology of cubic quantum dots, and by turning the halogen composition corresponding with lattice spacing maintains regularity. We used Tauc plot to calculate the difference of band gap energy as shown by the spectral shift which we found to be caused by the different ratios of Br and I and not because of their particle size difference. Furthermore, we focused on this all-inorganic perovskite-type quantum dot which was applied for the first time for white light emitting diodes. With varying proportions of blue, green and red QD’s, a narrow, white light-emitting material was produced. Further, mesoporous silica particle loaded with perovskite-type quantum dots was also investigated to resolve problems ofion-exchange during LED packaging and thus, effectively enhance the material's thermal and light stability. These novel nanocomposite perovskite-type quantum dots were successfully applied for LED devices.