臺灣博碩士論文加值系統

本篇研究利用原子層沉積技術 (ALD) 解決有機電子元件欲商業化所面臨的關鍵議題，包括: 在有機發光材料上加入ALD薄膜，使得光微影圖樣製程可適用於有機發光二極體 (OLEDs)，並增進元件效率；開發高阻氣性ALD薄膜封裝有機太陽能電池 (OSCs)，以及開發兼具高阻氣與電子傳遞功用之ALD薄膜，使得可撓式OSCs在大氣下可保有優異之穩定性。
在OLEDs的研究中，我們在發光材料 (本研究選用MEH-PPV) 上沉積10-Å之ALD氧化鋁薄膜，阻絕製程環境中溶劑或氣體與材料之直接接觸，使材料得以使用光微影技術形成圖樣而不受到任何的損害，此ALD氧化鋁薄膜在完成後可留存在元件中做為增進元件性能的緩衝層。雖然在進行ALD的過程中反應前驅物三甲基鋁會與MEH-PPV上的乙烯基進行加成反應，但此負面效應可藉由在MEH-PPV表面上以異丙醇進行前處理而獲得解決。
在OSCs的研究中，藉由最佳化ALD製程，我們開發了一個可同時對元件進行封裝並適度退火之製程。以聚(3-己烷基噻吩) (P3HT) 混掺6,6-苯基－碳61丁酸甲酯 (PCBM) 為吸光層之電池在經過140 ºC、1個小時之ALD封裝後，元件效率達3.66%。以26-nm之ALD氧化鋁-氧化鉿多層結構薄膜封裝之元件在大氣下可達到與在無水氧環境下相近之衰退速率。氧化鋁-氧化鉿多層結構解決了單一氧化鋁薄膜在大氣下會被水解的問題。除此之外，延長前驅物的曝露時間可以有效改善ALD薄膜在P3HT:PCBM上成核不易的問題。
在可撓式OSCs之研究中，我們開發了低溫製程 (90 ºC) 之ALD氧化鋅薄膜，此氧化鋅薄膜在P3HT:PCBM為吸光層之倒置型太陽能電池中，具有阻氣層以及電子收集層的雙重功用。藉由降低製程溫度至90 ºC以及延長前驅物水蒸氣的抽氣時間 (25秒)，所製備的氧化鋅薄膜具有高載子遷移率 (9.6 cm2/V s) 以及低載子濃度(2.1×1017 cm-3)，以玻璃為基板之元件效率可達4.06%。而此條件下之氧化鋅薄膜亦具有高阻氣率: 水氣穿透率為低於10-3 g/m2 day，氦氣氣體穿透率為5.03 cc/m2 day。高度吸濕性之聚(亞乙基二氧硫代酚)-聚(磺酸苯乙烯) (PEDOT:PSS) 是造成倒置型太陽能電池在大氣下衰退的主因，而藉由氧化鋅薄膜所提供優異之阻水特性可避免上述問題產生。以70-nm之ALD氧化鋅薄膜與26-nm ALD氧化鋁-氧化鉿多層結構薄膜封裝可撓曲之OSCs，元件效率起始效率為2.77%。元件在大氣下之衰退速率與元件在無水氧環境下相近，在經過1800個小時、65 ºC/60%相對溼度之加速環境下，可維持73%之起始效率。
本論文之研究成果對於OLEDs、OSCs，或是其他對於精細圖樣、電極界面改質或是阻氣封裝有需求之有機電子元件，具有高度參考價值，有利於促進有機電子元件之實用性。

This study utilized atomic layer deposition (ALD) to develop solutions to critical problems of organic electronics, including patterning-enabling and electron-injection- enhancing dual-functioning films for organic light-emitting diodes (OLEDs), gas-permeation barriers for the thin-film encapsulation of organic solar cells (OSCs), and permeation-blocking and electron-collecting dual-functioning films for flexible air-stable OSCs.
On OLEDs, we demonstrated that with a 10-Å ALD Al2O3 film overcoated on a poly[1-methoxy-4-(2’-ethyl-hexyloxy)-2,5-phenylenevinylene] (MEH-PPV) electro- luminescent layer, the OLEDs not only withstood an aggressive photolithographic patterning process without any degradation but unprecedentedly showed increased luminous efficiency. Although the ALD precursor, trimethylaluminum (TMA), was found to damage MEH-PPV through addition to MEH-PPV’s vinylene groups, its damaging effect was eliminated by pre-treating the MEH-PPV surface with isopropyl alcohol (IPA), whose hydroxyl groups scavenged TMA throughout the ALD process.
On the encapsulation of OSCs, we developed ALD processes that both prevented degradations caused by ambient gases and served as an annealing step that increased the initial power conversion efficiency (PCE) of the cells. With the ALD temperature set at 140 ºC and the deposition time set at 1 hr, OSCs based on blended poly-3- hexylthiophene (P3HT) and [6,6]-phenyl C61 butyric acid-methylester (PCBM), were optimally annealed during encapsulation, achieving a PCE of 3.66%. Encapsulating the cells with a 26-nm Al2O3/HfO2 nanolaminated film overcoated with an epoxy-resin protection layer enabled the cell to obtain an in-air degradation rate that was similar to cell stored in O2/H2O-free atmosphere. The Al2O3/HfO2 nanolaminated structure resolved the problem of hydrolysis-induced aging that occurred in single Al2O3 films, owing to the hydrophobicity of the HfO2 layers. Additionally, extended exposure of the ALD precursors during the ALD process ensured complete coverage of ALD films over the P3HT:PCBM layer at the perimeter of the cells.
On flexible air-stable OSCs, we developed low-temperature (90 ºC) ALD ZnO films as both gas barriers and electron-collection layers for P3HT:PCBM-based inverted OSCs. By utilizing a long purge time (25-s) and a low deposition temperature (90 ºC) in the ALD process, we obtained high electron mobility (9.6 cm2/V s) and low carrier concentration (2.1×1017 cm-3) in the ZnO films, thereby optimizing their electron- collecting function and achieving 4.06% PCE in the resultant inverted OSCs. Moreover, when deposited on poly(ethylene terephthalate) (PET) substrates, the ALD ZnO films at 70 nm of thickness showed excellent barrier properties: water vapor transmission rate (WVTR) < 10-3 g/m2 day and helium transmission rate (HeTR) of 5.03 cc/m2 day. This moisture-blocking capability was crucial for achieving air-stable inverted OSCs, as we determined that air-induced degradations of inverted OSCs mainly originated from moisture uptake by the poly(3,4-ethylene-dioxythiophene):polystyrene sulfonate (PEDOT:PSS) layer. Using an 70 nm ALD ZnO film for the electron-collection/barrier dual functions as well as a 26-nm Al2O3/HfO2 nanolaminate as the encapsulation layer, we demonstrated flexible OSCs on PET substrates with initial PCE of 2.77% and with negligible air-induced degradation: the OSCs showed near identical degradation rate as the control devices stored in an O2/H2O-free environment, and they retained 73% of their initial PCE over 1800 hr of storage under a 65 ºC/60% RH accelerated aging condition.
The results of my study will facilitate the practical applications of OLEDs and OSCs, as well as other types of organic electronics that require precise patterning, interface engineering and hermetic sealing.

Acknowledgement i
Abstract (Chinese) ii
Abstract (English) iv
Table of Contents vii
List of Figures xii
List of Tables xiii

Chapter 1 Introduction 1
1.1 Background 1
1.2 Motivations 3
1.3 Introduction to OLEDs 3
1.3.1 Overview 3
1.3.2 Concept of Buffer Layer 6
1.4 Introduction to OSCs 8
1.4.1 Overview 8
1.4.2 Bulk-Heterojunction (BHJ) Solar Cell 12
1.4.3 Instability Issues of OSCs 12
1.4.4 Inverted Structure of OSCs 14
1.5 Introduction to Atomic Layer Deposition (ALD) 16
1.6 Review of Patterning Technologies 22
1.6.1 Shadow-mask patterning 22
1.6.2 Inkjet printing 23
1.6.3 Screen printing 24
1.6.4 Dry etching 25
1.6.5 Photo-bleaching 26
1.6.6 Photolithography 27
1.7 Review of Encapsulation Methods 30
1.7.1 Glass Lid Encapsulation 31
1.7.2 Thin-Film Encapsulation 32
1.8 Objective Statement 36
1.9 Dissertation Organization 37
References 38
Chapter 2 Enhanced OLED Performance upon Photolithographic Patterning by Using an ALD Buffer Layer 48
2.1 Introduction 48
2.2 Experimental 51
2.2.1 Device Fabrication and Characterization 52
2.2.2 Spectral Characterization and Contact Angle Measurement 53
2.2.3 Atomic Layer Deposition 54
2.2.4 Photo-Patterning Process 55
2.3 Results and Discussion 56
2.3.1 Minimum Effective Thickness of ALD Film 56
2.3.2 Device Characteristics with ALD Buffer Layer 58
2.3.3 Adverse Effect of ALD on Devices Characteristics 60
2.3.4 IPA Pretreatment in ALD Process 65
2.3.5 Device Characteristics with Modified PEDOT:PSS Layer 73
2.3.6 Multi-Color OLEDs 74
2.4 Summary 76
References 77
Chapter 3 Thin-Film Encapsulation of Polymer-Based Bulk-Heterojunction Solar Cells by ALD 80
3.1 Introduction 80
3.2 Experimental 81
3.2.1 Device Fabrication and Characterization 82
3.2.2 Atomic Layer Deposition 83
3.2.3 Surface Characterization 84
3.2.4 Helium Permeation Measurement 85
3.3 Results and Discussion 87
3.3.1 Effect of ALD Encapsulation on PCEs 87
3.3.2 Degradation of OSCs under O2/H2O-free environment 91
3.3.3 Encapsulation Effectiveness of ALD Films 94
3.4 Summary 106
References 107

Chapter 4 Air-Stable, Polymer Bulk-Heterojunction Solar Cells on Plastic Substrate by Using ALD Encapsulation Layer 113
4.1 Introduction 113
4.2 Experimental 114
4.2.1 Device Fabrication and Characterization 115
4.2.2 Atomic Layer Deposition 117
4.2.3 Spectral Characterization 118
4.2.4 Gas Permeation Measurement 118
4.2.5 Hall-Effect Measurement 118
4.2.6 Conductivity Measurement 119
4.3 Results and Discussion 120
4.3.1 Effect of ALD Temperature on PCEs 120
4.3.2 Effect of ALD Temperature on Gas Permeability 125
4.3.3 Carrier Mobility Improvement 126
4.3.4 Degradation Mechanism of Non-Encapsulated Cell 131
4.3.5 Encapsulation Effectiveness of ALD Films 136
4.4 Summary 140
References 141
Chapter 5 Conclusion and Future Work 145
5.1 Conclusion 145
5.2 Directions for Future Research 148
5.2.1 Improve the Performance of Patterned OLEDs 148
5.2.2 Replace PEDOT:PSS with ALD p-Type Metal Oxide 149
Appendix 150

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[63]P. F. Carcia, R. S. McLean, M. H. Reilly, M. D. Groner and S. M. George, “Ca test of Al2O3 gas diffusion barriers grown by atomic layer deposition on polymers”, Appl. Phys. Lett., vol. 89, pp. 031915 (2006).
[64]A. P. Ghosh, L. J. Gerenser, C. M. Jarman and J. E. Fornalik, “Thin-lm encapsulation of organic light-emitting devices”, Appl. Phys. Lett., vol. 86, pp. 223503 (2005).
[65]S.-H. K. Park, J. Oh, C.-S. Hwang, J.-I. Lee, Y. S. Yang and H. Y. Chu, “Ultrathin film encapsulation of an OLED by ALD”, Electrochem. Solid-State Lett. vol. 8, pp. H21 (2005).
[66]W. J. Potscavage, S. Yoo, B. Domercq and B. Kippelen, “Encapsulation of pentacene/C60 organic solar cells with Al2O3 deposited by atomic layer deposition”, Appl. Phys. Lett., vol. 90, pp. 253511 (2007).

Chapter 2:
[1]A. DeFranco, B. S. Schmidt, M. Lipson and G. G. Malliaras, “Photolithographic patterning of organic electronic materials”, Org. Electron., vol. 7, pp. 22 (2006).
[2]J. Huang, R. Xia, Y. Kim, X. Wang, J. Dane, O. Hofmann, A. Mosley, A. J. de Mello, J. C. de Mello and D. D. C. Bradley, “Patterning of organic devices by interlayer lithography”, J. Mater. Chem., vol. 17, pp. 1043 (2007).
[3]S.-C. Chang, J. Bharathan, Y. Yang, R. Helgeson, F. Wudl, M. B. Ramey and J. R. Reynolds, “Dual-color polymer light-emitting pixels processed by hybrid inkjet printing”, Appl. Phys. Lett., vol. 73, pp. 2561 (1998).
[4]Y. Yang, S.-C. Chang, J. Bharathan and J. Liu, “Organic/polymeric electroluminescent devices processed by hybrid ink-jet printing”, J. Mater. Sci.: Mater. Electron., vol. 11, pp. 89 (2000).
[5]P. F. Tian, P. E. Burrows and S. R. Forrest, “Photolithographic patterning of vacuum-deposited organic light emitting devices”, Appl. Phys. Lett., vol. 71, pp. 3197 (1997).
[6] D. G. Lidzey, M. A. Pate, M. S. Weaver, T. A. Fisher and D. D. C. Bradley, “Photoprocessed and micropatterned conjugated polymer LEDs", Synth. Met., vol. 82, pp. 141 (1996).
[7] U. Wolf and H. Bässler , “Enhanced electron injection into light-emitting diodes via interfacial tunneling”, Appl. Phys. Lett., vol. 74, pp. 3848 (1999).
[8] S. T. Zhang, Y. C. Zhou, J. M. Zhao, Y. Q. Zhan, Z. J. Wang, Y. Wu, X. M. Ding and X. Y. Hou, “Role of hole playing in improving performance of organic light-emitting devices with an Al2O3 layer inserted at the cathode-organic interface”, Appl. Phys. Lett., vol. 89, pp. 043502 (2006).
[9] R. L. Puurunen, “Surface chemistry of atomic layer deposition: A case study for the trimethylaluminum/water process”, J. Appl. Phys., vol. 97, pp. 121301 (2005).
[10]M. D. Groner, F. H. Fabreguette, J. W. Elam and S. M. George, “Low-temperature Al2O3 atomic layer deposition”, Chem. Mater., vol. 16, pp. 639 (2004).
[11]C. J. Tonzola, M. M. Alam, W. Kaminsky and S. A. Jenekhe, “New n-type organic semiconductors: synthesis, single crystal structures, cyclic voltammetry, photophysics, electron transport, and electroluminescence of a series of diphenylanthrazolines”, J. Am. Chem. Soc., vol. 125, pp. 13548 (2003).
[12]R. Yang, H. Wu, Y. Cao and G. C. Bazan, “Control of cationic conjugated polymer performance in light emitting diodes by choice of counterion”, J. Am. Chem. Soc., vol. 128, pp. 14422 (2006).
[13]S.-H. Jin, S.-Y. Kang, M.-Y. Kim, Y. U. Chan, J. Y. Kim, K. Lee and Y.-S. Gal, “Synthesis and electroluminescence properties of poly(9,9-di-n-octyl- fluorenyl-2,7-vinylene) derivatives for light-emitting display”, Macromolecules, vol. 36, pp. 3841 (2003).
[14]M. M. Frank, Y. J. Chabal, M. L. Green, A. Delabie, B. Brijs, G. D. Wilk and M.-Y. Ho, “Enhanced initial growth of atomic-layer-deposited metal oxides on hydrogen-terminated silicon”, Appl. Phys. Lett., vol. 83, pp. 740 (2003).
[15]J. Huang, P. F. Miller, J. S. Wilson, A. J. de Mello, J. C. de Mello and D. D. C. Bradley, “Investigation of the effects of doping and post-deposition treatments on the conductivity, morphology, and work function of poly(3,4- ethylenedioxythiophene)/poly(styrene sulfonate) films”, Adv. Func. Mater., vol. 15, pp. 290 (2005).
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[17]S. T. Zhang, Y. C. Zhou, J. M. Zhao, Y. Q. Zhan, Z. J. Wang, Y. Wu, X. M. Ding and X. Y. Hou, “Role of hole playing in improving performance of organic light-emitting devices with an Al2O3 layer inserted at the cathode-organic interface,” Appl. Phys. Lett., vol. 89, pp. 043502 (2006).
[18]Y.-H. Niu, H. Ma, Q. Xu and A. K.-Y. Jen, “High-efficiency light-emitting diodes using neutral surfactants and aluminum cathode,” Appl. Phys. Lett., vol. 86, pp. 083504 (2005).
[19]X. J. Wang, J. M. Zhao, Y. C. Zhou, X. Z. Wang, S. T. Zhang, Y. Q. Zhan, Z. Xu, H. J. Ding, G. Y. Zhong, H. Z. Shi, Z. H. Xiong, Y. Liu, Z. J. Wang, E. G. Obbard and X. M. Ding, “Enhancement of electron injection in organic light-emitting devices using an Ag/LiF cathode,” J. Appl. Phys, vol. 95, pp. 3828 (2004).
[20]E. Ahlswede, W. Mühleisen, M. W. Wahi, J. Hanisch and M. Powalla, “Highly effcient organic solar cells with printable low-cost transparent contacts”, Appl. Phys. Lett., vol. 92, pp. 143307 (2008).

Chapter 3:
[1]M. Jorgensen, K. Norrman and F. C. Krebs, “Stability/degradation of polymer solar cells”, Sol. Energy Mater. Sol. Cells, vol. 92, pp. 686 (2008).
[2]K. Kawano, R. Pacios, D. Poplavskyy, J. Nelson, D. D. C. Bradley and J. R. Durrant, “Degradation of organic solar cells due to air exposure”, Sol. Energy Mater. Sol. Cells, vol. 90, pp. 3520 (2006).
[3]D. Gupta, M. Bag and K. S. Narayana, “Correlating reduced ll factor in polymer solar cells to contact effects”, Appl. Phys. Lett., vol. 92, pp. 093301 (2008).
[4]B. Paci, A. Generosi, V. R. Albertini, P. Perfetti, R. de Bettignies, M. Firon, J. Leroy and C. Sentein, “In situ energy dispersive x-ray reectometry measurements on organic solar cells upon working”, Appl. Phys. Lett., vol. 87, pp. 194110 (2005).
[5]B. Paci, A. Generosi, V.R. Albertini, P. Perfetti, R. de Bettignies, J. Leroy, M. Firon and C. Sentein, “Controlling photoinduced degradation in plastic photovoltaic cells: A time-resolved energy dispersive x-ray reectometry study”, Appl. Phys. Lett., vol. 89, pp. 043507 (2006).
[6]K. Norrman, N. B. Larsen and F. C. Krebs, “Lifetimes of organic photovoltaics: Combining chemical and physical characterisation techniques to study degradation mechanisms”, Sol. Energy Mater. Sol. Cells, vol. 90, pp. 2793 (2006).
[7]M. Drees, H. Hoppe, C. Winder, H. Neugebauer, N. S. Sariciftci, W. Schwinger, F. Schaeffler, C. Topf, M.C. Scharber, Z. Zhu and R. Gaudiana, “Stabilization of the nanomorphology of polymer–fullerene bulk heterojunction blends using a novel polymerizable fullerene derivative”, J. Mater. Chem., vol. 15, pp. 5158 (2005).
[8]C. H. Woo, B. C. Thompson, B. J. Kim, M.F. Toney and J. M. J. Fréchet, “The inuence of poly(3-hexylthiophene) regioregularity on fullerene-composite solar cell performance”, J. Am. Chem. Soc., vol. 130, pp. 16324 (2008).
[9]S. Bertho, G. Janssen, T.J. Cleij, B. Conings, W. Moons, A. Gadisa, J. D’Haen, E. Goovaerts, L. Lutsen, J. Manca and D. Vanderzande,. “Effect of temperature on the morphological and photovoltaic stability of bulk heterojunction polymer:fullerene solar cells”, Sol. Energy Mater. Sol. Cells, vol. 92, pp. 753 (2008).
[10]M. S. Weaver, L. A. Michalski, K. Rajan, M. A. Rothman, J. A. Silvernail, J. J. Brown, P. E. Burrows, G. L. Graff, M. E. Gross, P. M. Martin, M. Hall, E. Mast, C. Bonham, W. Bennett and M. Zumhoff,. “Organic light-emitting devices with extended operating lifetimes on plastic substrates”, Appl. Phys. Lett., vol. 81, pp. 2929 (2002).
[11]J. S. Lewis and M. S. Weaver, “Thin-film permeation-barrier technology for flexible organic light-emitting devices”, IEEE J. Sel. Top. Quantum Electron., vol. 10, pp. 45 (2004).
[12]G. L. Graff, R. E. Williford and P. E. Burrows, “Mechanisms of vapor permeation through multilayer barrier films: Lag time versus equilibrium permeation”, J. Appl. Phys., vol. 96, pp. 1840 (2004).
[13]J. Granstrom, J. S. Swensen, J. S. Moon, G. Rowell, J. Yuen and A. J. Heeger, “Encapsulation of organic light-emitting devices using a peruorinated polymer”, Appl. Phys. Lett., vol. 93, pp. 193304 (2008).
[14]M. D. Groner, S. M. George, R. S. McLean and P. F. Carcia, “Gas diffusion barriers on polymers using Al2O3 atomic layer deposition”, Appl. Phys. Lett., vol. 88, pp. 051907 (2006).
[15]P. F. Carcia, R. S. McLean, M. H. Reilly, M. D. Groner and S. M. George, “Ca test of Al2O3 gas diffusion barriers grown by atomic layer deposition on polymers”, Appl. Phys. Lett., vol. 89, pp. 031915 (2006).
[16]A. P. Ghosh, L. J. Gerenser, C. M. Jarman and J. E. Fornalik, “Thin-lm encapsulation of organic light-emitting devices”, Appl. Phys. Lett., vol. 86, pp. 223503 (2005).
[17]S.-H. K. Park, J. Oh, C.-S. Hwang, J.-I. Lee, Y. S. Yang and H. Y. Chu, “Ultrathin film encapsulation of an OLED by ALD”, Electrochem. Solid-State Lett. vol. 8, pp. H21 (2005).
[18]W. J. Potscavage, S. Yoo, B. Domercq and B. Kippelen, “Encapsulation of pentacene/C60 organic solar cells with Al2O3 deposited by atomic layer deposition”, Appl. Phys. Lett., vol. 90, pp. 253511 (2007).
[19]A. P. Ghosh, L. J. Gerenser, C. M. Jarman and J. E. Fornalik, “Thin-lm encapsulation of organic light-emitting devices”, Appl. Phys. Lett., vol. 86, pp. 223503 (2005).
[20]S.-H. K. Park, J. Oh, C.-S. Hwang, J.-I. Lee, Y. S. Yang and H. Y. Chu, “Ultrathin film encapsulation of an OLED by ALD”, Electrochem. Solid-State Lett. vol. 8, pp. H21 (2005).
[21]R. L. Puurunen, “Surface chemistry of atomic layer deposition: A case study for the trimethylaluminum/water process”, J. Appl. Phys., vol. 97, pp. 121301 (2005).
[22]F.-Y. Tsai, E. L. Alfonso, D. R. Harding and S. H. Chen, “Processing vapour-deposited polyimide”, J. Phys. D: Appl. Phys., vol. 34, pp. 3011 (2001).
[23]W. Ma, C. Yang, X. Gong, K. Lee and A. J. Heeger, “Thermally stable, efficient polymer solar cells with nanoscale control of the interpenetrating network morphology”, Adv. Funct. Mater., vol. 15, pp. 1617 (2005).
[24]M. Reyes-Reyes, K. Kim and D. L. Carroll, “High-efciency photovoltaic devices based on annealed poly(3-hexylthiophene) and 1-(3-(methoxycarbonyl)- propyl-1-phenyl-(6,6)C61 blends”, Appl. Phys. Lett., vol. 87, pp. 083506 (2005).
[25]K. Inoue, R. Ulbricht, P. C. Madakasira, W. M. Sampson, S. Lee, J. Gutierrez, J. P. Ferraris and A. A. Zakhidov, “Temperature and time dependence of heat treatment of RR-P3HT/PCBM solar cell”, Synth. Met., vol. 154, pp. 41 (2005).
[26]B. Paci, A. Generosi, V.R. Albertini, R. Generosi, P. Perfetti, R. de Bettignies and C. Sentein, “Time-resolved morphological study of bulk heterojunction films for efficient organic solar devices”, J. Phys. Chem. C, vol. 112, pp. 9931 (2008).
[27]B. Paci, A. Generosi, V.R. Albertini, P. Perfetti, R. de Bettignies, C. Sentein, “Photo-degradation and stabilization effects in operating organic photovoltaic devices by joint photo-current and morphological monitoring”, Sol. Energy Mater. Sol. Cells, vol. 92, pp. 799 (2008).
[28]C. W. T. Bulle-Lieuwma, W. J. H. van Gennip, J. K. J. van Duren, P. Jonkheijm, R. A. J. Janssen and J. W. Niemantsverdriet, “Characterization of polymer solar cells by TOF-SIMS depth profiling”, Appl. Surf. Sci., vol. 203, pp. 547 (2003).
[29]M. O. Reese, A. J. Morfa, M. S. White, N. Kopidakis, S. E. Shaheen, G. Rumbles, and D. S. Ginley, “Pathways for the degradation of organic photovoltaic P3HT:PCBM based devices”, Sol. Energy Mater. Sol. Cells, vol. 92, pp. 746 (2008).
[30]F. C. Krebs, “Encapsulation of polymer photovoltaic prototypes”, Sol. Energy Mater. Sol. Cells, vol. 90, pp. 3633 (2006).
[31]C. A. Wilson, R. K. Grubbs and S. M. George, “Nucleation and growth during Al2O3 atomic layer deposition on polymers”, Chem. Mater., vol. 17, pp. 5625 (2005).
[32]B. C. Bunker, G. C. Nelson, K.R. Zavadil, J. C. Barbour, F. D. Wall, J. P. Sullivan, C. F. Windisch, M. H. Engelhardt and D.R. Baer, “Hydration of passive oxide films on aluminum”, J. Phys. Chem. B, vol. 106, pp. 4705 (2002).
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[34]T. Nishide, S. Honda, M. Matsuda and M. Ide, “Surface, structural and optical properties of sol-gel derived HfO2 lms”, Thin Solid Films, vol. 371, pp. 61 (2000).
[35]S. J. Ding, D. W. Zhang and L.-K. Wang, “Atomic-layer-deposited Al2O3-HfO2 laminated and sandwiched dielectrics for metal–insulator–metal capacitors”, J. Phys. D: Appl. Phys., vol. 40, pp. 1072 (2007).
[36]M. S. Joo, B. J. Cho, C. C. Yeo, D. S. Chan, S. J. Whoang, S. Mathew, L. K. Bera, N. Balasubramanian and D. L. Kwong, “Formation of hafnium– aluminum–oxide gate dielectric using single cocktail liquid source in MOCVD process”, IEEE Trans. Electron Devices, vol. 50, pp. 2088 (2003).
[37]E. Langereis, M. Creatore, S. B. S. Heil, M. C. M. van de Sanden and W. M. M. Kessels, “Plasma-assisted atomic layer deposition of Al2O3 moisture permeation barriers on polymers”, Appl. Phys. Lett., vol. 89, pp. 081915 (2006).

Chapter 4:
[1]M. S. White, D. C. Olson, S. E. Shaheen, N. Kopidakis and D. S. Ginley, “Inverted bulk-heterojunction organic photovoltaic device using a solution- derived ZnO underlayer”, Appl. Phys. Lett., vol. 89, pp. 143517 (2006).
[2]B. Zimmermann, U. Würfel and M. Niggemann, Sol. Energy Mater. Sol. Cells, “Longterm stability of efficient inverted P3HT:PCBM solar cells”, vol. 93, pp. 491 (2009).
[3]A. K. K. Kyaw, X. W. Sun, C. Y. Jiang, G. Q. Lo, D. W. Zhao and D. L. Kwong, “An inverted organic solar cell employing a sol-gel derived ZnO electron selective layer and thermal evaporated MoO3 hole selective layer”, Appl. Phys. Lett., vol. 93, pp. 221107 (2008).
[4]J. S. Lewis and M. S. Weaver, “Thin-film permeation-barrier technology for flexible organic light-emitting devices”, IEEE J. Sel. Top. Quantum Electron., vol. 10, pp. 45 (2004).
[5]G. L. Graff, R. E. Williford and P. E. Burrows, “Mechanisms of vapor permeation through multilayer barrier films: Lag time versus equilibrium permeation”, J. Appl. Phys., vol. 96, pp. 1840 (2004).
[6]M. D. Groner, S. M. George, R. S. McLean and P. F. Carcia, “Gas diffusion barriers on polymers using Al2O3 atomic layer deposition”, Appl. Phys. Lett., vol. 88, pp. 051907 (2006).
[7]C.-Y. Chang, F.-Y. Tsai, S.-J. Jhuo and M.-J. Chen, “Enhanced OLED performance upon photolithographic patterning by using an atomic-layer- deposited buffer layer”, Org. Elec., vol. 9, pp. 667 (2008).
[8]M.-Y. Tsai and J.-C. Lin, “Preconditioning gold substrates influences organothiol self-assembled monolayer (SAM) formation”, J. Colloid Interface Sci., vol. 238, pp.259 (2001).
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[10]M. D. Groner, S. M. George, R. S. McLean and P. F. Carcia, “Gas diffusion barriers on polymers using Al2O3 atomic layer deposition”, Appl. Phys. Lett., vol. 88, pp. 051907 (2006).
[11]A. S. da Silva Sobrinho, G. Czeremuszkin, M. Latrèche and M. R. Wertheimer, “Defect-permeation correlation for ultrathin transparent barrier coatings on polymers”, J. Vac. Sci. Technol. A, vol. 18, pp. 149 (2000).
[12]N. Huby, S. Ferrari, E. Guziewicz, M. Godlewski and V. Osinniy, “Longterm stability of efficient inverted P3HT:PCBM solar cells”, Appl. Phys. Lett., vol. 92, pp. 023502 (2008).
[13]R. L. Puurunen, “Surface chemistry of atomic layer deposition: A case study for the trimethylaluminum/water process”, J. Appl. Phys., vol. 97, pp. 121301 (2005).
[14]T. Ameri, G. Dennler, C. Waldauf, P. Denk, K. Forberich, M. C. Scharber, C. J. Brabec and K. Hingerl, “Realization, characterization, and optical modeling of inverted bulk-heterojunction organic solar cells”, J. Appl. Phys., vol. 103, pp. 084506 (2008).
[15]D. C. Olson, S. E. Shaheen, R. T. Collins and D. S. Ginley, “The effect of atmosphere and ZnO morphology on the performance of hybrid poly(3-hexylthiophene)/ZnO nanofiber photovoltaic devices”, J. Phys. Chem. C, vol. 111, pp. 16670 (2007).
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[18]Z. Liang, A. Nardes, D. Wang, J. J. Berry and B. A. Gregg, “Defect Engineering in π-Conjugated Polymers”, Chem. Mater., vol. 21, pp. 4914 (2009).
[19]M. Jørgensen, K. Norrman and F.C. Krebs, “Stability/degradation of polymer solar cells”, Sol. Energy Mater. Sol. Cells, vol. 92, pp. 686 (2008).
[20]S. Chambon, A. Rivaton, J.-L. Gardette and M. Firon, “Photo- and thermal degradation of MDMO-PPV:PCBM blends”, Sol. Energy Mater. Sol. Cells, vol. 91, pp. 394 (2007).
[21]X. Crispin, S. Marciniak, W. Osikowicz, G. Zotti, A. W. Denier Vander Gon, F. Louwet, M. Fahlman, L. Groenendaal, F. Deschryver and W. R. Salaneck, “Conductivity, morphology, interfacial chemistry, and stability of poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate): A photoelectron spectroscopy study”, J. Polym. Sci. B:Polym. Phys., vol. 41, pp. 2561 (2003).
[22]M. Kuş and S. Okur, “Electrical characterization of PEDOT:PSS beyond humidity saturation”, Sens. Actuators B, vol. 143, pp. 177 (2009).
[23]T. J. Savenije, J. E. Kroeze, X.Yang and J. Loos, “The formation of crystalline P3HT fibrils upon annealing of a PCBM:P3HT bulk heterojunction”, Thin Solid Films, vol. 511–512, pp. 2 (2006).