臺灣博碩士論文加值系統

針對兩種相同元件結構但是不同敏化層組成的有機藍光二極體，利用磁場效應的角度研究主動層三重態-三重態湮滅上轉換(triplet-triplet annihilation upconversion (TTAUC))延遲螢光機制的運作情形。元件的敏化層和放光層皆有參與放光，透過定量fitting的方式驗證多光源系統下磁電致發光效應(magneto-electroluminescence (MEL))是emission-dependent的。室溫下磁電致發光效應的研究發現在敏化層中摻入少量Ir(ppy)3的元件能表徵到明顯提升的TTAUC efficiency，不僅驗證了文獻中提出的機制模型也表明少量Ir(ppy)3的摻入有助於利用大量long-lived triplet excitons和提升 energy transfer rate。另外變溫的磁電致發光效應研究發現到兩種元件的TTAUC在低溫下都沒有被增強，未摻雜的元件在低溫下因為Alq3的TTA effect增強，不利於放光層TTAUC的提升；而摻雜的元件在低溫下觀察到整體主動層的TTA強度有逐漸被弱化的趨勢，最後利用變溫磁電導效應(magnetoconductance (MC))表徵到隨溫度下降而漸增的triplet exciton charge reaction (即TPQ)，成功解釋了低溫下被抑制的TTA effect。

We investigate the photophysics in two blue organic light-emitting diodes through magnetic field effects (MFEs). The only difference between them is whether the sensitizer in the active layer is doped or not. Because both the sensitizer and the emitter contribute to the emission, we should individually extract each light source and then conduct subsequent mechanisms analysis. We successfully verify that doping a small amount of Tris[2-phenylpyridinato-C2,N] Iridium(III) (Ir(ppy)3) into the sensitizer is a critical method to both largely quench the green emission and enhance triplet-triplet annihilation (TTA) efficiency in the emitter simultaneously. Under the low-temperature conditions, we are unable to observe enhanced TTA in either device. In the case of the undoped device, there are no signs of unbalanced carrier behavior during the cooling process. However, an enhanced TTA feature is observed in the sensitizer, resulting in a reduction of triplet excitons available for TTA upconversion in the emitter. In the case of the doped device, we attribute the suppressed TTA phenomena, with the decreasing temperature, to the gradually stronger triplet exciton charge reaction.

摘要 I
Extended Abstract II
致謝 VII
目錄 VIII
圖目錄 XI
第一章 研究領域與動機 1
1.1 有機半導體的簡介 1
1.2 有機發光二極體的簡介 1
1.3 有機藍光二極體的發展 2
1.4 有機自旋電子學的簡介 10
1.5有機磁場效應的發展 12
1.6 實驗動機 19
第二章 有機材料自旋相關機制與磁場效應 20
2.1 有機材料的激發態 20
2.2 原子物理中的spin mixing processes 22
2.2.1 超精細結構作用(Hyperfine interaction (HFI)) 22
2.2.2自旋軌道耦合作用(Spin-orbit coupling (SOC)) 23
2.2.3 黎曼效應(Zeeman effect) 24
2.2.4 自旋交換耦合作用(Spin-exchange interaction) 25
2.3 磁場效應spin-dependent processes 25
2.3.1 Polaron-pair model (極化子對模型) 26
2.3.2 雙極化子模型(bipolaron model) 28
2.3.3 ∆g mechanism 29
2.3.4 Triplet-triplet annihilation (三重態-三重態湮滅) 29
第三章 元件製程與量測分析方法 31
3.1 有機藍光二極體的元件製程 31
3.2 元件基本光電特性的量測方式 34
3.2.1 Current density-Luminance-Voltage特徵曲線 34
3.2.2 電致發光光譜(electroluminescence spectrum) 34
3.3 磁場效應量測方式以及訊號處理 34
3.3.1 量測訊號與訊號處理 35
3.3.2 磁電致發光效應量測、磁電導效應量測以及低溫量測系統 37
第四章 有機藍光二極體TTAUC延遲螢光之磁場效應 38
4.1 未摻trilayer元件的磁場效應 38
4.1.1未摻trilayer元件的device performance 39
4.1.2 trilayer元件光譜與MEL response的關聯性 42
4.1.3 常溫條件下未摻trilayer元件的MEL response 45
4.1.4 變溫條件下未摻trilayer元件的磁場效應 50
4.1.5 章節小結 52
4.2 摻雜trilayer元件的磁場效應 53
4.2.1 摻雜trilayer元件的device performance 54
4.2.2 常溫條件下摻雜trilayer元件的MEL response 56
4.2.3 變溫條件下摻雜trilayer元件的磁場效應 59
4.2.4 章節小結 62
4.3 章節總結 62
第五章 結論與未來工作 63
5.1 結論 63
5.2 未來工作 64
參考文獻 66

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