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研究生： 鄭郁霖
Jheng, Yu-Lin
論文名稱： 側鏈含羥乙氧乙亞胺基團聚芴的合成、鑑定及其在電洞緩衝層之應用
Synthesis, Characterization and Hole-Buffering Application of Polyfluorene with Pendant Hydroxyethoxyethylimino Groups
指導教授： 陳雲
Chen, Yun
學位類別： 碩士
Master
系所名稱： 工學院 - 化學工程學系
Department of Chemical Engineering
論文出版年： 2019
畢業學年度： 107
語文別： 中文
論文頁數： 90
中文關鍵詞： 高分子發光二極體 、電洞緩衝 、聚芴 、亞胺 、濕式製程
外文關鍵詞： PLEDs, polyfluorene, solution process, hole buffer material
相關次數： 點閱：82  下載：1 
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    • 高分子發光二極體(PLEDs)本身具有良好發光特性，其發光機制是利用電激發光，即是電子跟電洞分別從陰極與陽極注入，傳輸到發光層再結合而發光。然而大部分有機材料的電洞傳輸速率都比電子還要快，會造成發光層載子不平衡，進而影響元件效率，因此降低電洞的傳輸速率則是讓高分子發光二極體效率提升的有效方法之一。
    本研究成功利用Suzuki Coupling Reaction分別合成出主鏈含聚芴基團側鏈含羥乙氧乙亞胺基團的高分子(PFI)，以核磁共振光譜(1H-NMR)、元素分析儀(EA)鑑定其結構，並分析其熱性質、光學性質、電化學性質及成膜性質，最後將其應用於高分子發光二極體的電洞緩衝層(Hole-Buffering Layer: HBL)，測量其發光二極體的電激發光特性。
    PFI的熱裂解溫度(Td)和玻璃轉移溫度(Tg)分別為319 oC及60 oC，其具有良好的熱穩定性；PFI的溶液態和薄膜態的最大吸收波長分別為383 nm及393 nm，而溶液態和薄膜態發光波長分別在417 nm及428 nm；從循環伏安法量測出PFI的最高占有分子軌域(HOMO)能階及最低未占有分子軌域(LUMO)分別為-5.63及-2.41 eV，從其HOMO能階低於發光層的HOMO能階(-5.0 eV)得知PFI具有電洞緩衝的特性。
    將PFI利用濕式製程中旋轉塗佈的方式製備電洞緩衝層(HBL)應用於電激發光元件(ITO/PEDOT:PSS/HBL/SY-PPV/LiF/Al)，在未加入電洞緩衝層的元件其最大亮度為6,138 cd/m2，最大電流效率為1.36 cd/A；加入PFI作為電洞緩衝層之元件，最大亮度提高至11,831 cd/m2，最大電流效率為5.08 cd/A。
    研究結果顯示，以PFI作為電洞緩衝層可以提升元件性能，原因除了其具有較佳的電洞緩衝能力外，還具有電子阻擋能力，使發光層的載子更加平衡，大幅度提升元件的效能，因此PFI是具有發展潛力的電洞緩衝材料。

    Polymer light-emitting diodes (PLEDs) have attracted considerable attention for its self-emissive ability, flexibility and high efficiency. Charge balance is an essential factor to enhance device efficiency. Hole mobility is always higher than electron mobility in most conjugated organic materials. Therefore, materials with low-lying HOMO level to reduce hole mobility are effective in enhancing efficiency of PLEDs. In this study, we successfully synthesized a new polyfluorene (PFI) by the Suzuki-coupling reaction; the PFI is composed of polyfluorene core with pendant hydroxyethoxyethylimino groups. The PFI was spin coated on top of PEDOT:PSS as hole-buffering layer (HBL). The HOMO and LUMO levels of PFI were -5.63 eV and -2.41 eV, respectively, as estimated from the onset oxidation and onset reduction potentials obtained in cyclic voltammetric measurements. Multilayer PLED devices were successfully fabricated [ITO/PEDOT:PSS/PFI(HBL)/SY-PPV/LiF/Al] using PFI as HBL. Their maximum luminance and maximum current efficiency were 11,831 cd/m2 and 5.08 cd/A, respectively, superior to those of the device without HBL (6,138 cd/m2, 1.36 cd/A). Current results indicate that the PFI is a potential hole-buffering materials applicable in optoelectronic devices.

    目錄 摘要 I 誌謝 XIV 目錄 XVIII 圖目錄 XX 表目錄 XXIII 第一章 緒論 1 1-1. 前言 1 1-2. 基礎理論 4 1-2-1. 有機材料的共軛導電特性 4 1-2-2. 螢光理論 5 1-2-3. 影響螢光強度之重要因素 8 1-2-4. 能量傳遞機制 10 1-2-5. 分子間激發子(Interchain Excitons)和分子內激發子(Intrachain Excitons) 12 1-3. 元件發光原理 14 1-3-1. 光激發光 14 1-3-2. 電激發光 15 1-4. 元件結構 17 1-4-1. 單層元件 17 1-4-2. 多層元件 19 第二章 文獻回顧 21 2-1. 有機電激發光材料的分類 21 2-1-1. 共軛高分子發光材料 22 2-1-2. 電子傳輸/電洞阻擋材料(ETM/HBM) 23 2-1-3. 電洞注入/傳輸材料(HIM/HTM) 24 2-1-4. 電洞緩衝材料(HBM) 25 2-2. 有機發光二極體的效率 27 2-2-1. 有機發光二極體效率的影響因素 27 2-2-2. 增進載子平衡的方法 28 2-3. 濕式製程 31 2-4. 希夫鹼的發現與應用 33 2-5. Suzuki-Miyaura Coupling Reaction 34 2-6. 研究動機 35 第三章 實驗內容 37 3-1. 實驗裝置與設備 37 3-2. 鑑定儀器 39 3-3. 物性與光電測量儀器 41 3-4. 實驗藥品與材料 51 3-5. 反應步驟與結果 53 3-6. 元件的製作與測量 56 3-6-1. 元件製作流程與清洗 56 3-6-2. 電洞注入層、電洞緩衝層、發光層的製作 57 3-6-3. Hole-Only元件製備 58 3-6-4. 蒸鍍系統 58 3-6-5. 元件測量 59 第四章 結果與討論 60 4-1. 化合物的合成與鑑定 60 4-1-1. 核磁共振光譜(NMR) 60 4-1-2. 元素分析儀(EA) 63 4-2. 高分子熱性質分析 64 4-2-1. 熱重分析(TGA) 64 4-2-2. 微差式掃描熱卡計分析(DSC) 65 4-3. 高分子光學性質分析 67 4-3-1. UV-Vis吸收光譜與PL發光光譜 67 4-4. 高分子電化學性質分析 70 4-5. 高分子成膜性質分析 73 4-6. 高分子發光二極體元件特性 76 4-6-1. 元件結構與能階 76 4-6-2. 元件電激發光性質 78 4-6-3. Hole-Only元件(HOD) 83 第五章 結論 85 參考資料 87 圖目錄 Fig. 1-2 1 共軛雙鍵鍵結。 4 Fig. 1 2-2 導體、半導體及絕緣體共價帶與傳導帶的能階分佈。 5 Fig. 1-2-3 基態、單重機發態與三重激發態中電子自旋的情形。 6 Fig. 1-2-4 分子能階示意圖。 7 Fig. 1-2-5 輻射能量轉移(輻射再吸收)。 10 Fig. 1-2-6 Förster非輻射能量轉移(庫倫作用力形式)。 11 Fig. 1-2-7 Dexter非輻射能量轉移(電子交換形式)。 11 Fig. 1-2-8 Donor與Acceptor光譜重疊[J (λ)為光譜重疊的程度]。 12 Fig. 1-2-9 (a) Interactions of AB collision pairs and A-*-B Exciplex. (b) Energy surface interpretation of Excimer or Exciplex emission. 13 Fig. 1-3-1 光激發光示意圖。 14 Fig. 1-3-2 電激發光示意圖。 15 Fig. 1-3-3 單重激發態與三重激發態轉換過程示意圖。 16 Fig. 1-4-1 單層元件結構示意圖。 18 Fig. 1-4-2 多層元件結構示意圖。 19 Fig. 1-4-3 常見的電子/電洞注入和傳輸層材料。 20 Fig. 2-1-1 有機電激發光材料結構之分類。 21 Fig. 2-1-2 常用的共軛高分子發光材料結構。 22 Fig. 2-1-3 常用的電子傳輸材料。 24 Fig. 2-1-4 PEDOT:PSS的結構示意圖。 25 Fig. 2-1-5 (a) CuPc之結構；(b)以CuPc做為電洞緩衝層之電流-電壓圖。 26 Fig. 2-2-1 為外部量子效率與元件發光機制圖。 28 Fig. 2-2-2 (a) BCP，(b) TPBi，(c) TmPyPB. 30 Fig. 2-3-1 (a)濕式製程的方法 (b)濕式製程的多層元件結構示意圖。 32 Fig. 2-4-1 希夫鹼結構與反應機制。 33 Fig. 2-5-1 A cycle for Suzuki Coupling Reaction. 34 Fig. 2-6-1 Structure of PFI. 36 Fig. 3-3-1 Three-electrode cells of the cyclic voltammetry. 43 Fig. 3-3-2 Schematic representation of (a) n-doping and (b) p-doping process in cyclic voltammetry. 44 Fig. 3-3-3 (a) The cyclic voltammogram of ferrocene; (b) The relative potential between the ferrocene and polymer. 45 Fig. 3-3-4 表面輪廓儀示意圖。 46 Fig. 3-3-5 AFM探針與待測樣品的作用情形。 47 Fig. 3-3-6 (a) AFM偵測方法示意圖，(b) AFM儀器簡圖。 47 Fig. 3-3-7 AFM force distance curve plots the deflection of the force-sensing cantilever during tip approach and retraction. 49 Fig. 3 6-1 Diagram illustration of the evaporation system. 58 Fig. 3-6-2 元件測量示意圖。 59 Fig. 4-1 1 1H-NMR spectrum of M1. 61 Fig. 4-1 2 1H-NMR spectrum of PFA. 61 Fig. 4-1 3 1H-NMR spectrum of PFI. 62 Fig. 4-2 1 Thermogravimetric curves of PFI at heating rate of 20 oC/min. 66 Fig. 4-2 2 Differential scanning calorimetric curves of PFI at a heating rate of 10 oC/min. 66 Fig. 4-3 1 Normalized UV/Vis absorption spectra and normalized photoluminescence spectra of PFI in CHCl3 solution and at film state. 69 Fig. 4-4 1 Cyclic voltammogram of PFI in 0.1 M (n-Bu)4NClO4; scan rate: 100 mV/s. 71 Fig. 4-4 2 (a) HOMO and (b) LUMO (c) LUMO+1 distributions of PFI repeating unit, obtained from simulation using Gaussian 09 software. [DFT-B3LYP/6-311G(d, p) level]. 72 Fig. 4-5 1 AFM images of the surface morphology of (a) PEDOT:PSS film cast on top of ITO and (b) PEDOT:PSS film by washing with DMF. (c-f) PFI films spin-coated on top of the PEDOT:PSS layer by using different spin rate: (c) 1000 rpm, (d) 2000 rpm, (e) 3000 rpm, (f) 4000 rpm. 75 Fig. 4-6 1 Chemical structure of PDY-132(SY-PPV). 77 Fig. 4-6 2 Energy level diagram of EL devices. 77 Fig. 4-6-3 Luminance versus voltage characteristics of EL devices. Device structure: ITO/PEDOT:PSS/PFI(x nm)/SY-PPV/LiF/Al. 80 Fig. 4-6-4 Current efficiency versus current density characteristics of EL devices. Device structure: ITO/PEDOT:PSS/PFI(x nm)/SY-PPV/LiF/Al. 80 Fig. 4-6-5 Current efficiency versus current density characteristics of EL devices. Device structure: ITO/PEDOT:PSS/PFI(x nm)/SY-PPV/LiF/Al. 81 Fig. 4-6-6 Luminous power efficiency versus current density characteristics of EL devices. Device structure: ITO/PEDOT:PSS/PFI(x nm)/SY-PPV/LiF/Al. 81 Fig. 4-6-7 EL spectrum of PLEDs. Device structure: ITO/PEDOT:PSS/PFI (x nm)/SY-PPV/LiF/Al. 82 Fig. 4-6-8 Current density versus voltage characteristics of the hole-only EL devices. Device structure: ITO/PEDOT:PSS/[with/without PFI (x nm)]/SY-PPV/LiF/Au. 84 表目錄 Table 1-1 1 Comparison between OLED and PLED 3 Table 1-2 1取代基對螢光波長與強度的影響 9 Table 2-2 1各種金屬的功函數 30 Table 4-1 1 Elemental analysis and reaction yields of polymers. 63 Table 4-2 1 Thermal properties of PFI 65 Table 4-3 1 Optical properties of PFI. 68 Table 4-4 1 Electrochemical properties of PFI. 71 Table 4-5 1 Root mean square roughness of polymer films. 74 Table 4-6 1 Electroluminescent properties of the devices with PFI. 79

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