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研究生:史梅君
研究生(外文):Mei-Chun Shih
論文名稱:上發光式白光有機發光元件之研製
論文名稱(外文):Study of White Top-emission Organic Light-emitting Diodes
指導教授:許渭州
指導教授(外文):Wei-Chou Hsu
學位類別:碩士
校院名稱:國立成功大學
系所名稱:微電子工程研究所碩博士班
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2009
畢業學年度:97
語文別:英文
論文頁數:85
中文關鍵詞:白光上發光
外文關鍵詞:top-emissionwhite
相關次數:
  • 被引用被引用:0
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摘要
本論文將製作白光元件所需的藍光發光層分為兩個發光區而得到一個色座標為(0.27,0.20)的近白光元件。接著藉由調整發光層及覆蓋層厚度,以及對陽極銀做不同時間與功率的氧化處理,最後得到一個最大效率為1.08 cd/A,最大亮度為10700 cd/m2的白光元件
我們最初的元件結構為: Ag (200 nm)/AgOx (2w, 80℃, 4 minutes)/NPB (40 nm)/TBADN:0.5 %Rubrene (30 nm)/Alq3 (10 nm)/TBADN (20 nm)/BCP (3nm)/Alq3 (4 nm)/LiF (1 nm)/Ag (20 nm)/Alq3 (20 nm),但是這樣的結構並無法有效激發出藍光,於是我們將結構做了兩個改良,一是將藍光發光層再分出另一個發光區,二是用NPB去取代Alq3,原因是NPB擁有比較大的折射率,且NPB的吸收光譜波峰小於Alq3,改良後結構如下: Ag (200 nm)/AgOx (2w, 80℃, 4 minutes)/NPB (40 nm)/TBADN1st (13 nm)/TBADN:0.5 %Rubrene (12 nm)/TBADN2nd (15 nm)/BCP (3 nm)/TBADN3rd (30 nm)/BCP (5 nm)/Alq3 (4 nm)/LiF (1 nm)/Ag (20 nm)/NPB (20 nm),在這個結構上我們得到了(0.27,0.22)的色座標,證明這個方法是可行的。
接著我們調整了覆蓋層厚度,好的覆蓋層雖然會提升出光率,然而過厚的厚度卻還是會阻礙光的產生,我們得到覆蓋層在40nm厚時所得到的效率及亮度是最佳的,因此我們的結構大致底定為: Ag (200 nm)/AgOx (2w, 80℃, 4 minutes) / NPB (40 nm)/TBADN1st (13 nm)/TBADN:0.5 %Rubrene (9 nm)/TBADN2nd (11 nm)/ Alq3 (1 nm)/BCP (3 nm)/TBADN3rd (30 nm)/BCP(5 nm)/Alq3 (4 nm)/LiF (1 nm)/Ag (20 nm)/NPB (40 nm)。
最後我們在陽極銀表面用PECVD做氧化處理,我們在實驗的一開始即用綠光元件去試驗PECVD氧化處理的功效並得到了有效的證實,在這裡我們用更多不同的參數去處理銀表面,並做成元件比較功效,同時我們也使用了ESCA去驗證了表面氧化銀的形成,最後我們得到在功率為兩瓦,溫度為攝氏八十度,處理時間為六分鐘時,元件可得到最佳的效率為1.08 cd/A,最佳亮度為10700cd/m2,色座標為(0.35,0.33),驅動電壓小於三伏特。
abstract
In this thesis, we fabricate a white top emission OLED by separating blue emitting layer to “dual-emitting blocks”, and then we optimize the structure to the best performance and modify the anode surface, finally we get the maximum efficiency of this white TOLED is 1.07 cd/A, and the maximum luminance is 10700 cd/m2.
At first, we got the experimental results that prove O2 plasma by PECVD can improve the performance of green TOLED, so we used the best parameter among those devices to treat on Ag anode as the foundation of our white TOLED
Second, we started from a basic structure: Ag (200 nm)/AgOx (2w, 80℃, 4 minutes)/NPB (40 nm)/TBADN:0.5 %Rubrene (30 nm)/Alq3 (10 nm)/TBADN (20 nm)/BCP (3nm)/Alq3 (4 nm)/LiF (1 nm)/Ag (20 nm)/Alq3 (20 nm), due to its weak blue emission, we not only separated the blue emitting layer to dual-emitting blocks but also changed the capping layer, because NPB has larger refractive index to improve out-coupling, and it has less blue absorption than Alq3, after several times modulations, we achieve a white TOLED which CIE coordinate is (0.35,0.33),and its maximum efficiency and luminance is 0.953 cd/a and 5720 cd/m2 .
After fabricating a white TOLED, we try to optimize the thickness of capping layer to improve out-coupling, and then we get the appropriate thickness is 40 nm, it can improve the luminance to 9640 cd/m2 .
Thirdly, we use different of rf power and time to treat on Ag anode, then we get the best performance occurred at 2w, 80℃, 6 minutes oxidation treatment, the best white TOLED structure is: Ag (200 nm)/AgOx (2w, 80℃, 6 minutes)/NPB (40 nm)/ TBADN (13 nm)/TBADN:0.5 %Rubrene (9 nm)/TBADN (11 nm)/Alq3 (1 nm)/BCP (3 nm)/TBADN (30 nm)/BCP (5 nm)/Alq3 (4 nm)/LiF (1 nm)/Ag (20 nm)/NPB (40 nm), the CIE coordinate is (0.35,0.33) and turn-on voltage is less than 3 V. At last, we use AFM and ESCA to prove the function of O2 plasma treatment on Ag.
CHAPTER 1 INTRODUCTION 1
1-1 HISTORY OF ORGANIC ELECTROLUMINESCENT DEVICES 1
1-2 THE MERITS OF TOP-EMISSION ORGANIC LIGHT EMITTING DIODES. 3
1-3 THESIS MOTIVATION 3
CHAPTER 2 ORGANIC LIGHT-EMITTING DEVICES 5
2-1 THE ORGANIC LIGHT-EMITTING THEOREMS 5
2-2 MECHANISM OF EMITTING LIGHT 7
2-3 OPTICAL PROCESSES IN OLEDS 9
2-3-1 Light generation 9
2-3-2 Light out-coupling 10
2-4 DESIGN OF ORGANIC LIGHT-EMITTING DIODES 10
2-4-1 Anode and cathode 11
2-4-2 Organic layer 14
2-5 BASICS OF MICROCAVITY 16
CHAPTER 3 FABRICATION AND MEASUREMENT 17
3-1 DEVICE FABRICATION PROCURE 17
3-1-1 Substrate cleaning 17
3-1-2 O2 plasma treatment on glass 17
3-1-3 Deposition of Ag anode 18
3-1-4 Oxidation treatment of Ag by PECVD 18
3-1-5 Deposition of organic thin films 19
3-1-6 Deposition of Ag cathode 19
3-2 MEASUREMENT SYSTEM 20
3-2-1 Measurement of light emission 20
3-2-2 Current-voltage measurement 22
3-2-3 Optical measurement 22
CHAPTER 4 EXPERIMENTAL RESULTS 24
4-1 OXIDATION BY PECVD 24
4-1-1 Device structure 25
4-1-2 Experimental results 25
4-2 WHITE TOP EMISSION OLEDS 27
4-2-1 Basic structure (device 1 and 2) 28
4-2-2 Device structure (device 3~6) 30
4-2-3 Device structure (device 7 and 8) 32
4-2-4 Device structure (device 8 and 9) 33
4-2-5 Device structure (device 8, 10, 11) 35
4-2-6 Device structure (device 10, 12, 13) 36
4-2-7 Device structure (device 10, 14, 15, 16, 17) 38
CHAPTER 5 DISCUSSION AND CONCLUSION 40
5-1 REFLECTION 40
5-2 ROUGHNESS 40
5-3 THE RATIO OF O:AG 41
5-4 CONCLUSION 42
REFERENCE 44
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