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研究生： 顏慧慈
Yan, Hui-Ci
論文名稱： 無機量子點色彩轉換微腔結構有機發光二極體之研究
Investigation of Color Conversion microcavity Organic Light-Emitting Diodes with Inorganic Quantum Dots
指導教授： 蘇炎坤
Su, Yan-Kuin
莊文魁
Ricky W. Chuang
學位類別： 碩士
Master
系所名稱： 電機資訊學院 - 微電子工程研究所
Institute of Microelectronics
論文出版年： 2012
畢業學年度： 100
語文別： 英文
論文頁數： 73
中文關鍵詞： 有機發光二極體 、微腔 、量子點 、白光發光二極體
外文關鍵詞： organic light-emitting diodes, microcavity, quantum dots, white light-emitting diodes
相關次數： 點閱：109  下載：4 
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    • 在本論文中主要使用藍綠光有機發光二極體與無機硒化鎘/硫化硒-核/殼量子點-聚甲基丙烯酸甲酯混合薄膜製作出色彩轉換有機發光二極體。有機發光二極體的基本結構為氧化銦錫 / NPB/ MADN:DSA-Ph/ Alq3/ 氟化鋰/ 鋁。本實驗中所有元件都成長於玻璃基板上， NPB為電洞傳輸層，MADN:DSA-Ph為藍光發光層 (MADN為主發光體、DSA-Ph為客發光體)，Alq3為電子傳輸層，氟化鋰為電子注入以及緩衝層、鋁為陰極。
    由於傳統以氧化銦錫作為陽極的發光元件展現出來的效能不夠好，因此在這裡我們也製作出以微共振腔結構為主的藍綠光有機發光二極體，其中元件的陽極是銀薄膜。銀薄膜與元件的上電極會形成微共振腔效應，進而提升元件的亮度與效率。另外我們發現蒸鍍氧化鉬薄膜可以修飾銀薄膜表面，並且可提升元件的發光強度以及減少元件的起始電壓。最後我們在元件的基板背後塗抹一層量子點-聚甲基丙烯酸甲酯混合薄膜，可作為調整發光顏色的材料。
    最後我們成功利用藍綠光有機發光二極體激發紅光無機量子點，進而實現具高色彩純度的白光。這兩種新穎結構的白光發光元件都有良好的電流穩定度，其中具有微共振腔結構的白光元件展現較高的發光效率，但它的色彩飽和度較不理想。相較於基本結構的白光元件，其效率由每毫安培1.35燭光量提升了42.9%至1.93燭光量；在操作電流為6毫安培之下，亮度由每平方公尺6047燭光量提升了64 %至9904燭光量，色度座標為(0.306, 0.323)，色溫為6910。

    In this study, the color conversion organic light-emitting diodes (OLEDs) were fabricated by using the blue-green OLEDs and red emitting CdSe/ZnS core/shell quantum dots (QDs). The basic structure of the OLEDs was composed by indium tin oxide (ITO)/ N,N′-Di-[(1-naphthyl)-N,N′-diphenyl]-1,1′ biphenyl)-4,4′-diamine (NPB)/ 2-methyl-9,10- di(2-napthyl)anthracene:p-bis(p-N,N-diphenyl-aminostyryl)benzene (MADN:DSA-Ph)/ tris-(8-hydroxyquinoline)aluminum (Alq3)/ lithium fluoride (LiF)/ aluminum (Al). All of the devices were deposited on glass substrates. NPB, MADN:DSA-Ph, Alq3, LiF, and Al were used as the hole transporting layer, emitting layer, electron transporting layer, electron injection layer and cathode, respectively.
    To improve the light emitting efficiency of our blue-green emitting devices, the microcavity OLEDs consist of the semi-transparent silver (Ag) thin film as the bottom mirror and Al film as the top mirror was fabricated. Besides, the molybdenum trioxide (MoO3) thin film could be well-deposited on the Ag film by thermal evaporation, result in the enhancement of light emitting efficiency and decreaseing the turn on voltage for microcavity OLEDs. Finally, the QD-PMMA composite film was wiped on the backside of the glass substrates to be used as the color conversion layer.
    The red emitting QDs were successfully excited by blue-green light emitting devices and the pure white organic light-emitting diodes (WOLEDs) were achieved by introducing the intensity adjustment of the three-band spectra. Both WOLEDs showed high color stability, despite the increase of the operation current. WOLEDs with microcavity structures also exhibited higher light efficiency. Nevertheless, the pure white light wasn’t easily obtained. The luminous efficiency and luminance was 1.93 cd/A and 9904 cd/m2 at 6 mA, respectively, which was enhanced by 42.9 % and 64 % in comparison with that of 1.35 cd/A and 6047cd/m2 for WOLEDs based on basic structures, respectively. The CIE coordinates were (0.306, 0.323), and the correlated color temperature (CCT) was 6910.

    Abstract(in Chinese) I Abstract(in English) II Acknowledgement IV Content V Table captions VII Figure captions VIII Chapter1 Introduction 1 1-1 Development of organic light-emitting diodes 1 1-2 Advantages of organic light-emitting diode 2 1-3 The development of microcavity organic light-emitting diodes 3 1-4 Motivation 4 Chapter2 Theory of organic light-emitting diodes 5 2-1 The structure and principle of organic light-emitting diodes 5 2-1-1 The varieties of organic light-emitting diodes 5 2-1-2 The function of each individual layer of OLEDs 6 2-1-3 The operating principle of OLEDs 10 2-1-4 The current mechanism [42] 12 2-2 The characteristics of organic materials 13 2-2-1 Fluorescence and Phosphorescence 13 2-2-2 The energy transfer mechanism 14 2-3 The properties and mechanism of microcavity OLEDs 17 2-3-1 Microcavity effect 17 2-3-2 Influences on OLEDs’ characteristics 18 Chapter3 Experiment instruments and process 21 3-1 The materials in the experiments 21 3-2 Substrate treatment 26 3-3 The deposition process 27 3-4 Measurement and characteristics analysis 29 Chapter4 Experiment results and discussion 32 4-1 Comparison of conventional and microcavity OLEDs 32 4-2 Using green microcavity OLEDs to excite red light from QDs 38 4-2-1 Optimizing the thickness of emitting layer in green microcavity OLEDs 38 4-2-2 Using green microcavity OLEDs to excite QDs 44 4-3 The Optimal condition of blue-green microcavity OLEDs for white light 49 4-3-1 Using dopant to enhance the characteristics of the blue-green light emitting devices 49 4-3-2 Optimizing the cavity thickness in blue-green microcavity OLEDs 55 4-4 Using blue-green light emitting devices to excite QDs for white light emission 60 Chapter5 Conclusion and future work 66 5-1 Conclusion 66 5-2 Future work 67 Reference 68

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