臺灣博碩士論文加值系統

高分子有機電激發光二極體 ( PLED ) 因擁有釵h優點而廣泛受到各界矚目，目前國內外有釵h研究機構致力於製程改良及改善載子傳輸效率以增進元件之效能，但針對載子傳輸效率的相關研究多僅止於材料開發及合成，鮮少探討元件各層界面形貌對其光電性能的影響。
本論文針對 ITO / MEH-PPV 的接觸界面進行探討，以原子力顯微鏡量測ITO 的表面形貌並以表面粗度參數描述之，其後運用表面接觸力學探討不同的 ITO 表面型貌所造成其與MEH-PPV薄膜層間之接觸面積的改變，將其與元件性能的變化做一比較並加以分析，結果顯示 ITO 之Rq ( Root Mean Square，表面均方根粗度值 ) 會對元件於低電壓時由電洞穿隧所主宰之電流密度造成影響。Rq也會影響到電洞於MEH-PPV薄膜中的移動率。而 ITO 與 MEH-PPV 的接觸面積則會影響電洞欲穿隧過ITO / MEH-PPV 界面時所需克服的能障高度。

Polymer Light Emitting Diodes ( PLED ) become a subject of intensive research because it holds great promises to overcome many deficiencies of other display technology. Recent studies on the device efficiency of PLED indicate that there is an imminent need to understand the effect of interface morphology.
This research focuses on the interface of ITO / MEH-PPV. The surface morphology of ITO is characterized by Scanning probe microscopy (SPM). The mechanical property of ITO and MEH-PPV is measured using nanoindentation technique. The testings for device efficiency include I-V characteristics, barrier height and hole transmission. Our findings show that surface roughness as described by the Rq (root mean square of surface height) of ITO surface affects the current density dominated by hole tunneling under low voltage. The Rq of ITO surface also influences the hole mobility. While the contact area between ITO and MEH-PPV affects barrier height for hole to tunnel through the interface of ITO / MEH-PPV.

目錄
致謝………………………………………………………………… Ⅰ
中文摘要…………………………………………………………… Ⅱ
英文摘要…………………………………………………………… Ⅲ
目錄………………………………………………………………… Ⅳ
表目錄……………………………………………………………… Ⅶ
圖目錄……………………………………………………………… Ⅷ
第一章 緒論……………………………………………………… 1
1-1 前言…………………………………………………… 1
1-2 研究動機……………………………………………… 4
1-3 論文架構……………………………………………… 6
第二章 文獻回顧………………………………………………… 8
2-1 高分子電激發光原理………………………………… 8
2-2 高分子發光二極體之電性理論………………………… 11
2-3 高分子發光二極體的元件結構………………………… 18
2-4 高分子電激發光元件的發展沿革……………………… 21
2-5 奈米壓痕量測理論……………………………………… 25
2-5-1 硬度……………………………………………………… 25
2-5-2 楊氏係數………………………………………………… 26
2-6 粗度理論回顧…………………………………………… 28
2-7 表面接觸力學理論回顧………………………………… 32
第三章 實驗方法………………………………………………… 37
3-1 實驗設計與流程………………………………………… 37
3-2 實驗儀器與設備………………………………………… 39
3-3 實驗藥品與材料………………………………………… 44
3-4 PLED元件製備…………………………………………… 45
第四章 結果討論…………………………………………………… 47
4-1 單層PLED ( ITO/MEH-PPV/Al )元件的製程參數選擇…47
4-2 ITO與MEH-PPV薄膜硬度及楊氏係數之量測.………… 48
4-3 MEH-PPV與ITO間接觸面積之估算概念………………… 49
4-3-1 ITO與MEH-PPV的材料性質……………………………… 49
4-3-2 MEH-PPV及Al陰極所施加於ITO上的荷重……………… 49
4-3-3 ITO薄膜上尖峰的型態及其分佈密度…………………… 50
4-4 Indium Tin Oxide 經KOH 蝕刻後對其表面之影響……51
4-5 PLED電性分析…………………………………………………52
4-5-1 Thermionic Emission 與 ITO 表面Rq 值及薄膜間接觸
面積之相關性………………………………………… 52
4-5-2 F-N Tunneling與ITO表面 Rq 值及薄膜間接觸面積之相
關性…………………………………………………… 53
4-5-3 SCLC 及 Hole Mobility 與 ITO 表面 Rq 值及薄膜間接
觸面積之相關性……………………………………… 55
第五章 總結………………………………………………………… 57
第六章 未來展望…………………………………………………… 59
參考文獻……………………………………………………………… 60




表目錄

表 1 PLED與OLED之間的主要差異………………………………… 64
表 2 PLED亮度實驗的實驗計畫…………………………………… 65
表 3 能障高度與ITO之Rq值及ITO / MEH-PPV之接觸面積
的關係…………………………………………………………… 65
表 4 載子移動率與ITO之Rq值及ITO / MEH-PPV之接觸面積的
關係……………………………………………………………… 66





圖目錄

Fig 1. 接觸情形示意圖…………………………………………… 67
Fig 2. p軌域重疊的π-π鍵結形成雙鍵………………………… 67
Fig 3. 高分子電激發光二極體示意圖…………………………… 68
Fig 4. 元件能階及電激發光示意圖……………………………… 68
Fig 5. 螢光與磷光的形成示意圖………………………………… 69
Fig 6. 電子與電洞在高分子發光體中經再結合後的能量分配
……………………………………………………………… 69
Fig 7. 表現Fowler-Nordhiem Tunneling 機制的能帶圖…… 70
Fig 8. (a)單層型元件 (b)雙層型元件之一 (c)雙層型元件之二
(d)三層型元件之一 (e)三層型元件二…………………… 70
Fig 9. 美國Kodak公司於1887年首創採用異質接面之元件結構圖
…………………………………………………………… 73
Fig 10. 英國Cambridge大學Cavendish實驗室利用PPV製備而成
的單層有機電激發光元件結構圖………………………… 73
Fig 11. 相同Ra值，不同的表面粗糙分佈情況…………………… 74
Fig 12. 參數RSk對表面的敏感程度……………………………… 74
Fig 13. 參數RKU對表面的敏感程度……………………………… 75
Fig 14. 單一粗糙波峰的變形情況………………………………… 75
Fig 15. 橢圓峰端彈性變形接觸幾何示意圖……………………… 76
Fig 16. 接觸表面示意圖…………………………………………… 76
Fig 17. 超音波震盪機 ( Ultrasonic Cleaner ) ………… 77
Fig 18. 旋轉塗佈機 ( Spin-Coater ) ……………………… 77
Fig 19. 真空烤箱 ( Vacuum Oven ) ………………………… 78
Fig 20. 蒸鍍機 ( Thermal Evaporator ) ………………… 78
Fig 21. 原子力顯微鏡工作原理示意圖…………………………… 79
Fig 22. 原子力顯微鏡 ( Atomic force microscope，AFM ) …… 79
Fig 23. Nano-indenter 主要組成結構圖……………………………… 80
Fig 24. Nano-indenter 之壓痕器結構圖……………………………… 80
Fig 25. 轉換器之結構示意圖……………………………………………… 81
Fig 26. 奈米壓痕量測儀 ( Nanoindenter ) ………………………… 81
Fig 27. 輝度計 ( Luminance meter ) ……………………………… 82
Fig 28. 電源電壓供應器 ( Source meter ) ………………………… 82
Fig 29. PLED元件結構示意圖……………………………………………… 83
Fig 30. PLED亮度實驗中相關因子的反應圖……………………………… 83
Fig 31. 參數設計後的PLED元件之L-V Curve…………………………… 84
Fig 32. 參數設計後的PLED元件之I-V Curve…………………………… 84
Fig 33. Force vs Penetration of ITO Thin Film……………… 85
Fig 34. Force vs Penetration of MEH-PPV Thin Film ………… 85
Fig 35. Hardness vs Force of ITO Thin Film…………………… 86
Fig 36. Hardness vs Penetration of ITO Thin Film…………… 86
Fig 37. Young’s Modulus vs Force of ITO Thin Film………… 87
Fig 38. Young’s Modulus vs Penetration of ITO Thin Film… 87
Fig 39. Hardness vs Force of MEH-PPV Thin Film……………… 88
Fig 40. Hardness vs Penetration of MEH-PPV Thin Film……… 88
Fig 41. Young’s Modulus vs Force of MEH-PPV Thin Film…… 89
Fig 42. Young’s Modulus vs Penetration of MEH-PPV Thin Film… 89
Fig 43. (a)(b)(c)(d)(e) ITO經KOH+Isopropanol 蝕刻後的表面形貌
……………………………………………………………………………… 90
Fig 44. LogJ vs LogV Plot with Different Surface Morphology……… 92
Fig 45. Fowler-Nordheim Tunneling Plot with Different Surface
Morphology…………………………………………………………………… 93
Fig 46. Barrier Height vs Contact Area Plot……………………………… 93
Fig 47. 粗糙界面之電傳導示意圖……………………………………………………… 94
Fig 48. LogJ vs LogV Plot with Different Surface Morphology……… 94
Fig 49. Hole Mobility VS Rq Plot……………………………………… 95

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