臺灣博碩士論文加值系統

在本論文中，我們提出幾種可以有效提昇有機發光二極體效率與色純度之元件結構，包括下發光式白光元件、上發光式綠光元件，以及上發光式白光元件等。其中我們使用螢光材料TBADN作為藍光主體材料，使用螢光材料rubrene作為黃色?雜材料，並藉由兩者依適當之?雜比例來獲得具高色純度之白光元件。另一方面我們使用螢光材料Alq3作為綠光主體材料，搭配具高量子效率之綠光?雜材料C545T，在適當的?雜比例下可以獲得理想之綠光元件。在下發光式白光元件之製作中，由於藍光主體材料(TBADN)之HOMO能階與電子傳輸層(Alq3)之HOMO能階幾乎相同，所以無法有效讓載子於發光層進行再結合。對此我們利用一Alq3薄層將發光層隔成兩部份，再藉由電洞阻隔層(BCP)之使用，可以將元件之效率從4.26 cd/A提升至5.44 cd/A。但由於BCP層之LUMO能階較接近Rubrene之LUMO能階，造成電子較容易注入Rubrene材料，進而使元件之色度明顯偏向黃光。對此我們再將各發光層拆為?雜與未?雜等兩部份，實驗結果顯示元件之色度已有所改善。最後我們再嚐試將發光層之間的Alq3替換成TPBi材料，由於TPBi材料具有較大之HOMO能階，可以有效將電洞阻擋於發光層中，因此元件之效率可以提升至6.09 cd/A，同時元件於9伏操作電壓之CIE座標為(0.32, 0.32)，顯示元件具有相當理想之色純度表現。我們亦使用TBADN藍光主體材料與Rubrene黃光?雜材料於上發光式白光元件，其元件結構為Ag(200 nm)/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)。其中由於TBADN之螢光效率偏低，且藍光對於銀薄膜之穿透率較低，所以我們於元件中設計三層不同厚度之藍光發光層，並用電洞阻隔層(BCP)來提升載子於TBADN層之再結合率，進而補強藍光之發光亮度。元件於5伏操作電壓之CIE座標為(0.35, 0.33)，顯示其具有很理想之白光色度表現。對於上發光式元件之製作，我們採用了銀金屬作為發光元件之陽極，並使用兩種不同之氧化製程來進行銀金屬之表面處理，包括紫外線-臭氧和化學氣相沉積法。其中使用紫外線-臭氧之處理方式，我們發現隨著曝照時間之增加，銀金屬之表面功函數也隨之增加；但同時其表面電阻也會隨之增加，且其表面反射率也會隨之降低，因此我們找到最佳之曝照時間為3分鐘。另一方面，使用化學氣相沉積法之表面處理方式，於不同操作功率以及氧化時間下，發光元件之電性會有明顯之變化，且最佳處理條件為2瓦之操作功率以及6分鐘之氧化時間。在上發光式綠光元件之製作中，我們於Alq3主體材料中?入高量子效率之C545T材料，同時於元件加入厚度為2 nm之電洞阻隔層(BCP)。由於BCP材料之LUMO能階較接近C545T之LUMO能階，可以提升C545T之發光效率，進而提升綠光元件之整體效率。於1%之?雜濃度下，綠光元件之電流效率可以從5.19 cd/A有效地提升至19.43 cd/A。另一方面，對於上發光式白光元件之製作，藉由銀陽極之表面氧化處理，元件之電流效率可以從0.56 cd/A提升至1.08 cd/A，且元件於5伏操作電壓下之CIE座標為(0.35, 0.33)，顯示元件具有相當理想之白光色純度表現。

This dissertation presents various organic light-emitting diode (OLED) structures with high efficiency and high color purity, including those with bottom-emission white light, top-emission green light, and top-emission white light. In the design of a white light device, TBADN is used as the blue host and rubrene is used as the yellow dopant. Alq3 is used as the green host, doped with C545T fluorescent material, to obtain a high-performance green light device. The carriers do not recombine effectively in the emission layer because the HOMO energy level of the blue host (TBADN) is almost the same as that of the electron transporting layer (Alq3). The emission layer is divided into two layers by another thin Alq3 layer, and a hole-blocking layer (BCP) is inserted between the emission layer and the electron transporting layer. The current efficiency of white light device was thus improved from 4.26 cd/A to 5.44 cd/A. However, the yellow emission of the device is enhanced by the small energy barrier of LUMO between BCP and rubrene, affecting the color purity of the white light device. The emission layer is divided into a doped layer and an undoped layer, and the experimental results reveal that the color purity of white light is significantly improved. The TBADN and rubrene are also used for top-emission white-OLEDs with the device structure Ag(200 nm)/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). Since TBADN has low efficiency and the Ag film has low transparency to blue emission, three blue-emitting layers of different thickness and a hole-blocking layer are applied to enhance the blue emission in this work. The CIE coordinate of the device at 5 V indicates that it has high color purity. To fabricate a top-emission device, Ag was used as the anode and two methods of oxidation were utilized to treat the Ag surface. They were the UV-ozone method and PECVD. The work function of Ag increases with the period of exposure in UV-ozone treatment. However, such treatment also increases the sheet resistance and degrades the surface reflectance. The optimal exposure time was around 3 minutes in the experiment performed in this study. However, the performance of an OLED device that has undergone PECVD treatment is determined by the operating power and the oxidation time. The optimal conditions were 2 W for 6 minutes in the experiment herein.
In the fabrication a top-emission OLED, C545T, which has high quantum efficiency, was doped into an Alq3 host and a 2nm-thick hole-blocking layer (BCP) was used deposited on the host. The LUMO of BCP is close to that of C545T and hence increasing the C545T emission and device efficiency. The current efficiency of the green-OLED is improved from 5.19 cd/A to 19.43 cd/A under a 1% doping concentration. The current efficiency of a top-emission white-OLED is improved from 0.56 cd/A to 1.08 cd/A using Ag-anode oxidation. The CIE coordinate of the device at 5 V is (0.35, 0.33), indicating the good color purity of the white-OLED.

Abstract (In Chinese)
Abstract (In English)
Contents I
Table Captions III
Figure Captions IV

Chapter 1 Introduction
1.1 Background 1
1.2 Overview of the dissertation 3

Chapter 2 Improved Organic Light-emitting Diodes with Modified Dual-emission- layer Designs
2.1 Introduction 6
2.2 Device structure and fabrication 7
2.3 Experimental results and discussion 9
2.4 Summary 15

Chapter 3 Efficiency Improvement of Top-emission Organic Light-emitting Diode by Using UV-ozone, Doped Emission Layer, and Hole-blocking Layer
3.1 Introduction 16
3.2 Device structure and fabrication 17
3.3 Experimental results and discussion 18
3.4 Summary 23

Chapter 4 Improved Efficiency and High Color Purity of Top-emission White Organic Light Emitting Diode by Anode Oxidation Technique
4.1 Introduction 25
4.2 Device structure and fabrication 26
4.3 Experimental results and discussion 28
4.4 Summary 34

Chapter 5 Conclusion and future works
5.1 Conclusion 35
5.2 Future works 36

References 38

[1]C. Y. Lee, D. E. Lee, Y. K. Hong, J. H. Shim, C. K. Jeong, J. Joo, D. S. Zang, M. G. Shim, J. J. Lee, J. K. Cha, and H. G. Yang, “Matrix formalism of electromagnetic wave propagation through multiple layers in the near-field region: Application to the flat panel display, Phys. Rev. E, vol. 67, p. 046605, 2003.
[2]S. Z. Deng, K. Wang, Jun Chen, Y. Q. Zhang, and N. S. Xu, “Study of a microprocessor-based technique for improving the uniformity of a field-emission flat-panel display, J. Vac. Sci. Technol. B, vol. 21, p. 523, 2003.
[3]S. O. Kim, “Protective layer using plasma polymerized thin films in ac-plasma display panel, J. Vac. Sci. Technol. B, vol. 21, p. 233, 2003.
[4]T. J. Vink, A. R. Balkenende, R. G. F. A. Verbeek, H. A. M. van Hal, and S. T. de Zwart, “Materials with a high secondary-electron yield for use in plasma displays, Appl. Phys. Lett., vol. 80, p. 2216, 2002.
[5]Y. Asao, H. Yoshinaga, H. Mori, H. Munakata, R. Isobe, H. Mizuno, T. Togano, N. Nishida, and Y. Hanyu, “Dot Inversion Spontaneous Polarization Structure in the Half-V-shaped Switching Ferroelectric Liquid Crystal Mode, Jpn. J. Appl. Phys., vol. 42, p. 554, 2003.
[6]Y. Iwamoto and Y. Iimura, “Transmitted Light Enhancement of Electric-Field-Controlled Multidomain Vertically Aligned Liquid Crystal Displays Using Circular Polarizers and a Cholesteric Liquid Crystal Film, Jpn. J. Appl. Phys., vol. 42, p. 51, 2003.
[7]Y. Iwamoto and Y. Iimura, “Transmittance Enhancement for Randomly Aligned Liquid Crystal Displays with Circular Polarizers, Jpn. J. Appl. Phys., vol. 41, p. 1383, 2002.
[8]T. Y. Yoon, J. H. Park, J. Sim, and S. D. Lee, “Self-formation of microdomains by the topographical and fringe field effects in a liquid crystal display with dielectric surface gratings, Appl. Phys. Lett., vol. 81, p. 2361, 2002.
[9]T. Tsujimura and A. Makita, “Molybdenum/aluminum stacked metal taper etching for high-resolution thin-film transistor liquid-crystal display, J. Vac. Sci. Technol. B, vol. 20, p. 1907, 2002.
[10]C. W. Tang and S. A. VanSlyke, “Organic electroluminescent diodes, Appl. Phys. Lett., vol. 51, p. 913, 1987.
[11]C. W. Tang and S. A. VanSlyke, “Electroluminescence of doped organic thin films, J. Appl. Phys., vol. 65, p. 3610, 1989.
[12]A. Bernanose, “Electroluminescense of organic compounds, Brit. J. Phys. Suppl., vol. 4, p. 54, 1955.
[13]M. Pope, H. Kallmann, P. Magnant, “Electroluminescence in organic crystals, J. Chem. Phys., vol. 38, p. 2042, 1963.
[14]W. helfrich and W. G. Schneider, “Recombination radiation in anthracene crystals, Phys. Rev. Lett., vol. 140, p. 229, 1965.
[15]D. F. Williams and M. Schadt, “A simple organic electroluminescence diode, Proc. IEEE Lett., vol. 58, p. 476, 1970.
[16]P. S. Vincent, W. A. Barlow, R. A. Hann, G. G. Roberts, “Electrical conduction and low voltage blue electroluminescence in vacuum-deposited organic films, Thin Solid Films, vol. 94, p. 476, 1982.
[17]G. G. Roberts, M. McGinnity, P. S. Vincett, W. A. Barlow, “Electroluminescence photoluminescence and electroabsorption of a lightly substituted anthracene langumuir film, Solid State Commun., vol. 32, p. 683, 1979.
[18]C. Adachi, M. A. Baldo, S. R. Forrest, and M. E. Thompson, “High-efficiency organic electrophosphorescent devices with tris (2- phenylpyridine) iridium doped into electron-transporting materials, Appl. Phys. Lett., vol. 77, p. 904, 2000.
[19]M. A. Baldo, S. Lamansky, P. E. Burrows, M. E. Thompson, and S. R. Forrest, “Very high-efficiency green organic light-emitting devices based on electro- phosphorescence, Appl. Phys. Lett., vol. 75, p. 4, 1999.
[20]S. Tokito, T. Tsutsui, and Y. Taga, “Microcavity organic light-emitting diodes for strongly directed pure red, green, and blue emissions, J. Appl. Phys., vol. 86, p. 2407, 1999.
[21]S. E. Shaheen, G. E. Jabbour, M. M. Morrell, Y. Kawabe, B. Kippelen, “Bright blue organic light-emitting diode with improved color purity using a LiF/Al cathode, J. Appl. Phys., vol. 84, p. 2324, 1998.
[22]K. H. Weinfurtner, H. Fujikawa, S. Tokito, and Y. Taga, “Highly efficient pure blue electroluminescence from polyfluorene: Influence of the molecular weight distribution on the aggregation tendency, Appl. Phys. Lett., vol. 76, p. 2502, 2000.
[23]C. C. Wu, Y. T. Lin, H. H. Chiang, T. Y. Cho, C. W. Chen, K. T. Wong, Y. L. Liao, G. H. Lee, and S. M. Peng, “Highly bright blue organic light-emitting devices using spirobifluorene-cored conjugated compounds, Appl. Phys. Lett., vol. 81, p. 577, 2002.
[24]A. Shoustikov, Y. You, and P. E. Burrows, “Orange and redorganic light emitting devices using aluminum tris (5-hydroxyquinoxaline), Synthetic Metals, vol. 91, p. 217, 1997.
[25]J. Lam, T. C. Gorjanc, Y. Tao, and M. D'lorio “Selective doping of multilayer organic light emitting devices, J. Vac. Sci. Technol. A, vol. 18, p. 593, 2000.
[26]G. Y. Zhong, J. He, S. T. Zhang, Z. Xu, Z. H. Xiong, H. Z. Shi, and X. M. Ding, “In situ photoluminescence investigation of doped Alq, Appl. Phys. Lett., vol. 80, p. 4846, 2002.
[27]P. Ranke, I. Bleyl, J. Simmerer, and D. Haarer “Electroluminescence and electron transport in a perylene dye, Appl. Phys. Lett., vol. 71, p. 1332, 1997.
[28]T. Mori, H. G. Kim, T. Mizutani, and D. C. Lee “Electroluminescent Properties in Organic Light-Emitting Diode Doped with Two Guest Dyes, Jpn. J. Appl. Phys., vol. 40, p. 5346, 2001.
[29]R. Banerjee, S. Ray, N. Basu, A. K. Batabyal, and A. K. Barua, “Degradation of tin-doped indium-oxide film in hydrogen and argon plasma, J. Appl. Phys., vol. 62, p. 912, 1987.
[30]S. Major, S. Kumar, M. Bhatnagar, and K. L. Chopra, “Effect of hydrogen plasma treatment on transparent conducting oxides, Appl. Phys. Lett., vol. 49, p. 394, 1986.
[31]A. Misra, P. Kumar, M. N. Kamalasanan, and S. Chandra, “White organic LEDs and their recent advancements, Semicond. Sci. Technol., vol. 21, p. 35, 2006.
[32]R. F. Service, “Organic LEDs look forward to a bright, white future, Science, vol. 310, p. 1762, 2005.
[33]B. W. D’Andrade and S. R. Forrest, “White organic light-emitting devices for solid-state lighting, Adv. Mater., vol. 16, p. 1585, 2004.
[34]J. H. Jou, M. H. Wu, C. P. Wang, Y. S. Chiu, P. H. Chiang, H. C. Hu, “Efficient fluorescent white organic light-emitting diodes using co-host/emitter dual-role possessed di(triphenyl-amine)-1,4-divinyl- naphthalene, Org. Elect., vol. 8, p. 735, 2007.
[35]F. Wei, X. Zhang, J. Cao, M. A. Khan, W. Q. Zhu, X. Y. Jiang, and Z. L. Zhang, “Highly efficient styrylamine-doped blue and white organic electroluminescent devices, Displays, vol. 28, p. 186, 2007.
[36]J. H. Jou, Y. S. Chiu, C. P. Wang, R. Y. Wang, and C. Hu, “Efficient, color-stable fluorescent white organic light-emitting diodes with single emission layer by vapor deposition from solvent premixed deposition source, Appl. Phys. Lett., vol. 88, p. 193501, 2006.
[37]Y. C. Tsai and J. H. Jou, “Long-lifetime, high-efficiency white organic light-emitting diodes with mixed host composing double emission layers, Appl. Phys. Lett., vol. 89, p. 243521, 2006.
[38]C. H. Chuen, Y. T. Tao, and C. F. Shu, “White organic light-emitting diodes based on 2,7-bis(2,2-diphenylvinyl)-9,9 '-spirobifluorene: Improvement in operational lifetime, Appl. Phys. Lett., vol. 85, p. 4609, 2004.
[39]G. Li and J. Shinar, “Combinatorial fabrication and studies of bright white organic light-emitting devices based on emission from rubrene-doped 4,4 '-bis(2,2 '-diphenylvinyl)-1,1 '-biphenyl, Appl. Phys. Lett., vol. 83, p. 5359, 2003.
[40]K. O. Cheon and J. Shinar, “Bright white small molecular organic light-emitting devices based on a red-emitting guest-host layer and blue-emitting 4,4(')-bis(2,2(')-diphenylvinyl)-1,1 '-biphenyl, Appl. Phys. Lett., vol. 81, p. 1738, 2002.
[41]C. H. Chuen and Y. T. Tao, “Highly-bright white organic light-emitting diodes based on a single emission layer, Appl. Phys. Lett., vol. 81, p. 4499, 2002.
[42]Y. S. Huang, J. H. Jou, W. K. Weng, and J. M. Liu, “High-efficiency white organic light-emitting devices with dual doped structure, Appl. Phys. Lett., vol. 80, p. 2782, 2002.
[43]C. W. Ko and Y. T. Tao, “Bright white organic light-emitting diode, Appl. Phys. Lett., vol. 79, p. 4234, 2001.
[44]M. D. Joswick, I. H. Campbell, N. N. Barashkov, and J. P. Ferraris, “Systematic investigation of the effects of organic film structure on light emitting diode performance, J. Appl. Phys., vol. 80, p. 2883, 1996.
[45]X. Y. Jiang, Z. L. Zhang, W. Q. Zhu, and S. H. Xu, “Study of blue organic light emitting diode by inserting a red dye ultra thin layer at the emitting layer, J. Phys. D, vol. 38, p. 4153, 2005.
[46]S. L. Tao, Z. R. Hong, Z. K. Peng, W. G. Ju, X. H. Zhang, P. F. Wang, S. K. Wu, and S. T. Lee, “Anthracene derivative for a non-doped blue-emitting organic electroluminescence device with both excellent color purity and high efficiency, Chem. Phys. Lett., vol. 397, p. 1, 2004.
[47]M. A. Khan, W. Xu, J. Cao, Y. Bal, W. Q. Zhu, X. Y. Jiang, and Z. L. Zhang, “Spectral studies of white organic light-emitting devices based on multi-emitting layers, Displays, vol. 28, p. 26, 2007.
[48]J. J. Lih, C. I. Chao, and C. C. Lee, “Novel pixel design for high-resolution AMOLED displays with a shadow mask, J. SID, vol. 15, p. 3, 2007.
[49]R. F. Service, “Organic LEDs look forward to a bright, white future, Science, vol. 310, p. 1762, 2005.
[50]R. J. Tseng, R. C. Chiechi, F. Wudl, and Y. Yang, “Highly efficient 7,8,10-triphenylfluoranthene-doped blue organic light-emitting diodes for display application, Appl. Phys. Lett., vol. 88, p. 093512, 2006.
[51]R. Q. Brown, R. Hewitt, K. Rajan, J. Silvernail, K. Urbanik, M. Hack, and J. J. Brown, “Flexible active-matrix OLED displays: Challenges and progress, J. SID, vol. 16, p. 169, 2008.
[52]C. W. Han, M. K. Han, W. J. Nam, S. J. Bae, and I. B. Kang, “A top-emitting organic light-emitting diode employing a top-cathode connected to amorphous silicon TFTs, J. Electro. Soci., vol. 154, p. 306, 2007.
[53]M. H. Lu, M. S. Weaver, T. X. Zhou, M. Rothman, R. C. Kwong, M. Hack, and J. J. Brown, “High-efficiency top-emitting organic light-emitting devices, Appl. Phys. Lett., vol. 81, p. 3921, 2002.
[54]C. J. Yang, S. H. Liu, H. H. Hsieh, C. C. Liu, T. Y. Cho,and C. C. Wu, “Microcavity top-emitting organic light-emitting devices integrated with microlens arrays: Simultaneous enhancement of quantum efficiency, cd/A efficiency, color performances, and image resolution, Appl. Phys. Lett., vol. 91, p. 253508, 2007.
[55]T. F. Guo, F. S. Yang, Z. J. Tsai, G. W. Feng, T. C. Wen, S. N. Hsieh, C. T. Chung, and C. I. Wu, “High-brightness top-emissive polymer light-emitting diodes utilizing organic oxide/Al/Ag composite cathode, Appl. Phys. Lett., vol. 89, p. 051103, 2006.
[56]Q. Huang, K. Walzer, M. Pfeiffer, V. Lyssenko, G. F. He, and K. Leo, “Highly efficient top emitting organic light-emitting diodes with organic outcoupling enhancement layers, Appl. Phys. Lett., vol. 88, p. 113515, 2006.
[57]S. F. Chen, Y. Zhao, G. Cheng, J. Li, C. L. Liu, Z. Y. Zhao, Z. H. Jie, and S. Y. Liu, “Improved light outcoupling for phosphorescent top-emitting organic light-emitting devices, Appl. Phys. Lett., vol. 88, p. 153517, 2006.
[58]C. W. Chen, P. Y. Hsieh, H. H. Chiang, C. L. Lin, H. M. Wu, and C. C. Wu, “Top-emitting organic light-emitting devices using surface-modified Ag anode, Appl. Phys. Lett., vol. 83, p. 5127, 2003.
[59]H. W. Choi, S. Y. Kim, K. B. Kim, Y. H. Tak, and J. L. Lee, “Enhancement of hole injection using O-2 plasma-treated Ag anode for top-emitting organic light-emitting diodes, Appl. Phys. Lett., vol. 86, p. 012104, 2005.
[60]H. J. Peng, J. X. Sun, X. L. Zhu, X. M. Yu, M. Wong, H. S. Kwok, “High-efficiency microcavity top-emitting organic light-emitting diodes using silver anode, Appl. Phys. Lett., vol. 88, p. 073517, 2006.
[61]C. J. Lee, R. B. Pode, D. G. Moon, and J. I. Han, “Realization of an efficient top emission organic light-emitting device with novel electrodes, Thin Solid Films, vol. 467, p. 201, 2004.
[62]S. F. Hsu, C. C. Lee, S. W. Hwang, and C. H. Chen, “Highly efficient top-emitting white organic electroluminescent devices, Appl. Phys. Lett., vol. 86, p. 253508, 2005.
[63]B. W. D’Andrade and S. R. Forrest, “White organic light-emitting devices for solid-state lighting, Adv. Mater., vol. 16, p. 1585, 2004.
[64]B. Geffroy, R. P. Le, C. Prat, “Organic light-emitting diode (OLED) technology: materials, devices and display technologies, Polym. Int., vol. 55, p. 572, 2006.
[65]K. Hong and J. L. Lee, “Inverted top-emitting organic light-emitting diodes using transparent silver oxide anode formed by oxygen plasma, Electrochem. Solid ST., vol. 11, p. 29, 2008.
[66]J. T. Lim, C. H. Jeong, J. H. Lee, G. Y. Yeom, E. C. Shin, E. H. Lee, and T. W. Kim, “Inverted top-emitting organic light-emitting diodes using transparent silver oxide anode formed by oxygen plasma, J. Electrochem. Soc., vol. 154, p. 302, 2007.
[67]Q. Huang, K. Walzer, M. Pfeiffer, V. Lyssenko, G. F. He, and K. Leo, “Highly efficient top emitting organic light-emitting diodes with organic outcoupling enhancement layers, Appl. Phys. Lett., vol. 88, p. 113515, 2006.
[68]T. Ishibashi, J. Yamada, T. Hirano, Y. Iwase, Y. Sato, R. Nakagawa, M. Sekiya, T. Sasaoka, and T. Urabe, “Active matrix organic light emitting diode display based on Super Top Emission technology, Jpn. J. Appl. Phys., vol. 45, p. 4392, 2006.
[69]C. W. Chen, P. Y. Hsieh, H. H. Chiang, C. L. Lin, H. M. Wu, and C. C. Wu, “Top-emitting organic light-emitting devices using surface-modified Ag anode, Appl. Phys. Lett., vol. 83, p. 5127, 2003.
[70]M. H. Lu, M. S. Weaver, T. X. Zhou, M. Rothman, R. C. Kwong, M. Hack, and J. J. Brown, “High-efficiency top-emitting organic light-emitting devices, Appl. Phys. Lett., vol. 81, p. 3921, 2002.
[71]J. J. Huang, H. Y. Ueng, Y. K. Su, S. J. Lin, and F. S. Juang, “Thickness for Optimizing of Organic Layer and Multi-Layer Anode on Luminance Efficiency in White-Light Top-Emission Organic Light-Emitting Diodes, J. Nanosci Nanotechno., vol. 8, p. 5176, 2008.
[72]S. F. Hsu, C. C. Lee, S. W. Hwang, and C. H. Chen, “Highly efficient top-emitting white organic electroluminescent devices, Appl. Phys. Lett., vol. 86, p. 253508, 2005.
[73]H. Kanno, Y. Sun, and S. R. Forrest, “High-efficiency top-emissive white-light-emitting organic electrophosphorescent devices, Appl. Phys. Lett., vol. 86, p. 263502, 2005.
[74]H. W. Choi, S. Y. Kim, K. B. Kim, Y. H. Tak, and J. L. Lee, “Enhancement of hole injection using O-2 plasma-treated Ag anode for top-emitting organic light-emitting diodes, Appl. Phys. Lett., vol. 86, p. 012104, 2005.
[75]H. J. Peng, J. X. Sun, X. L. Zhu, X. M. Yu, M. Wong, H. S. Kwok, “High-efficiency microcavity top-emitting organic light-emitting diodes using silver anode, Appl. Phys. Lett., vol. 88, p. 073517, 2006.
[76]Y. N. Lai, W. C. Hsu, C. S. Lee, C. W. Wang, C. S. Ho, T. Y. Lu, and W. F. Lai, “Efficiency Improvement of Top-Emission Organic Light Emitting Diode by Using UV-Ozone, Doped Emission Layer, and Hole-Blocking Layer, J. Electrochem. Soc., vol. 157, p. 25, 2010.