吳忠幟臺灣大學：光電工程學研究所洪文誼Hung, Wen-YiWen-YiHung2007-11-252018-07-052007-11-252018-07-052005http://ntur.lib.ntu.edu.tw//handle/246246/50647在有機光電元件中，有機半導體之電荷傳輸能力，即載子之遷移率(carrier mobility)是影響元件特性之重要因素，因此量測在有機層中電荷傳輸特性對於元件運作之機制具有重要的意義，同時高載子遷移率材料的研究亦是有機光電半導體中持續的重要課題。在此論文，我們利用飛行時間式電荷傳輸特性量測系統(Time-of-Flight System, TOF)研究新的電荷傳輸材料以及載子在有機薄膜中的傳導特性。我們發現含口夫 喃寡聚物(non-amine-based furan-containing oligoaryls)具有良好電洞傳輸特性，運用此新材料作為有機發光元件之電洞傳輸層時，元件之電特性及發光特性都優於被廣泛使用之芳香胺類電洞傳輸材料。此外，我們揭露三聚芴化物(Terfluorene)具有罕見之高效率雙極性電荷傳遞特性，並比較三聚芴化合物在不同取代基下的電荷傳輸特性，發現具旋環結構鍵結芳香環取代基之三聚芴化合物，不但提供空間阻隔以增加形態(morphology)穩定性及發光效率，並能有效地增加分子間的傳輸能力。利用三聚芴化物之高效率雙極性傳輸特性，我們還發展出一新型TOF Mobility量測架構，利用一薄層三聚芴化物當作載子產生層，成功地量測到各種OLED材料的載子移動率。最後，我們利用三聚芴化物摻雜至聚碳酸酯(PC)，探討具小分子摻雜之聚合物之電荷傳遞特性及物理機制，並發現其具良好雙極性傳輸特性，具有應用於有機光導體的潛力。Charge transport in organic material plays a crucial role in performances of organic optoelectronic devices. In this thesis, we used the time-of-flight measurement technique to study charge-transport properties of various materials. In the first part of the work, we found that a class of furan-containing oligoaryls that contain no amine moiety could be used as hole-transport materials for OLEDs and devices incorporating such compounds exhibited promising characteristics. In the second part of the work, unprecedented nondispersive ambipolar carrier transport was revealed for a series of terfluorenes. Carrier-transport properties of terflurenes with different types of C9 substitutions were compared. We found that by introducing spiroconjugation between a core chromophore and spiro-linked conjugated substitutions, the bulky substitution not only serves as a spatial hindrance to enhance morphological stability and emission efficiency in the solid states, but can also bridge and enhance intermolecular charge transport, yet still with electronic properties of the core chromophore rather intact. In the third part of the , a new TOF measurement configuration using terflourenes as the charge-generation layer in TOF measurements is discussed. We successfully used this method to measure charge-transport properties of a wide range OLED materials, which otherwise are more difficult to measure by traditional TOF techniques. Finally, we investigated the charge-transporting properties of terflourene-dispersed polymers with different concentrations. Efficient bipolar transport was observed in such MDP systems, indicating potential applications in eletrophotography as organic photoreceptors.Chapter1:Introduction 1 1-1 Overview 1 1-2 Organic Light-Emitting Diodes 3 1-3 Organic Photoconductors 6 1-4 Current Issues in Organic Charge Transport Materials 9 1-5 Thesis Organization 12 Chapter 2: Experimental Methods 18 2-1 Introduction 18 2-2 Principles of Time-of-Flight Mobility Measurement 19 2-3 Analysis with Transient TOF Signals 24 2-4 Preparation of TOF Samples 25 2-5 Material Preparation and Characterization 27 2-6 EL Device Fabrication and Characterization 29 Chapter 3: Models of Charge Transport in Disordered Organic Systems 34 3-1 Introduction 34 3-2 Charge Hopping 35 3-3 Poole-Frenkel Model 37 3-4 Bässler Formalism 39 3-4.1 Low-Field Case 40 3-4.2 Field Dependent Case 42 3-4.3 Nondispersive-to-dispersive Transition 45 3-5 Concentration Dependence of Mobility 46 Chapter 4: Hole-Transport Properties of a Furan-Containing Oligoaryl 55 4-1 Introduction 55 4-2 Materials Properties 57 4-3 EL Device Characteristics 59 4-4 Charge Transport Properties 61 Chapter 5: Nondispersive Ambipolar Carrier Transport in Terfluorenes 83 5-1 Introduction 83 5-2 Materials Properties 84 5-3 Mobility Measurements of Terfluorenes 86 5-3.1 TOF Results of E3 87 5-3.2 TOF Results of B3 89 5-3.3 TOF Results of T3 91 5-4 Results and Discussions 93 5-4.1 Nondispersive Bipolar Carrier Transport of Terfluorenes 93 5-4.2 Comparison of E3, B3, T3 95 Chapter 6: TOF Mobility Measurement Employing Terfluorene as Charge-Generation Layer 122 6-1 Introduction 122 6-2 Principles of Charge-Generation-Layer TOF 123 6-3 Results and Discussions 125 6-3.1 Mobility of ADN (Emitting Host) 125 6-3.2 Mobility of TPBE (Emitting Guest) 127 6-3.3 Mobility of TPBI (Electron Transport Material) 129 Chapter 7: Charge Transport in Terflourene -Dispersed Polymer Systems 147 7-1 Introduction 147 7-2 Preparation and Mobility Measurements of E3-dispersed Polymers with Different Concentrations 149 7-2.1 Polycarbonate dispersed with 66 wt.% E3 151 7-2.2 Polycarbonate dispersed with 50 wt.% E3 153 7-2.3 Polycarbonate dispersed with 40 wt.% E3 155 7-3 Results and Discussions 157 7-3.1 Comparison with MDP Systems in Conventional OPCs 157 7-3.2 Concentration Dependence 158 Chapter 8: Summary and Future Direction 185 8-1 Summary 185 8-2 Future Direction 1871910571 bytesapplication/pdfen-US載子傳輸有機半導體遷移率Organic SemiconductorsCharge TransportMobilityTOFthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/50647/1/ntu-94-D89941005-1.pdf