Flexible Flat Panel Displays

Darran R. Cairns, PhD, is a member of the Faculty in the School of Science & Engineering at University of Missouri - Kansas City, USA. His research interests include solution-based processing of composite materials including sol-gel materials, nano-composite materials, and liquid crystalline materials and composites. Dirk J. Broer, is a Polymer Chemist specialized in polymer structuring and self-organizing polymer networks. This entails the development of polymers with new functionalities and integrating them into devices to meet industrial and societal challenges in the fields of sustainable energy, water-management, healthcare and personal comfort. Gregory P. Crawford, PhD, is President of Miami University, USA, and Professor of Physics. His research interests include liquid crystal and polymer materials for display and biotechnology applications. He is the editor of the first edition of Flexible Flat Panel Displays (2005).

• Series Editor’s Foreword xvList of Contributors xvii1 Introduction 1Darran R. Cairns, Gregory P. Crawford, and Dirk J. Broer1.1 Toward Flexible Mobile Devices 11.2 Flexible Display Layers 21.3 Other Flexible Displays and Manufacturing 22 Engineered Films for Display Technology 5W.A. MacDonald2.1 Introduction 52.2 Factors Influencing Film Choice 52.2.1 Application Area 52.2.2 Physical Form/Manufacturing Process 62.2.3 Film Property Set 72.2.3.1 Polymer Type 72.2.3.2 Optical Clarity 92.2.3.3 Birefringence 102.2.3.4 The Effect of Thermal Stress on Dimensional Reproducibility 102.2.3.5 Low-bloom Films 112.2.3.6 Solvent and Moisture Resistance 122.2.3.7 The Effect of Mechanical Stress on Dimensional Reproducibility 162.2.3.8 Surface Quality 182.3 Summary of Key Properties of Base Substrates 192.4 Planarizing Coatings 212.5 Examples of Film in Use 232.6 Concluding Remarks 24Acknowledgments 253 Liquid Crystal Optical Coatings for Flexible Displays 27Owain Parri, Johan Lub, and Dirk J. Broer3.1 Introduction 273.2 LCN Technology 273.3 Thin-film Polarizers 293.3.1 Smectic Polarizers 293.3.2 Cholesteric Polarizers 323.4 Thin-film Retarders 343.4.1 Reactive Mesogen Retarders 353.4.2 Chromonic Liquid Crystal-based Retarders 373.4.3 Liquid Crystal Alignment and Patterned Retarders 373.5 Color Filters 413.6 Conclusion 434 Large Area Flexible Organic Field-effect Transistor Fabrication 47Zachary A. Lamport, Marco Roberto Cavallari, and Ioannis Kymissis4.1 Introduction 474.2 Substrates 484.3 Photolithography 494.4 Printing for Roll-to-roll Fabrication 524.4.1 Inkjet Printing 524.4.2 Gravure and Flexographic Printing 554.4.3 Screen Printing 564.4.4 Aerosol Jet Printing 564.4.5 Contact Printing 584.4.6 Meniscus Dragging 604.5 Conclusions 625 Metallic Nanowires, Promising Building Nanoblocks for Flexible Transparent Electrodes 67Jean-Pierre Simonato5.1 Introduction 675.2 TEs Based on Metallic Nanowires 685.2.1 Metallic Nanowires, New Building Nanoblocks 685.2.2 Random Network Fabrication 695.2.3 Optical Characterization 705.2.4 Electrical Characterization 715.2.5 Mechanical Aspect 735.3 Application to Flexible Displays 735.3.1 Touch Screens 735.3.2 Light-emitting Diodes Displays 745.3.3 Electrochromic Flexible Displays 765.3.4 Other Displays 775.4 Conclusions 786 Optically Clear Adhesives for Display Assembly 85Albert I. Everaerts6.1 Introduction 856.2 OCA Definition and General Performance Specifications 866.3 Application Examples and Challenges 896.3.1 Outgassing Tolerant Adhesives 906.3.2 Anti-whitening Adhesives 916.3.3 Non-corrosive OCAs 926.3.4 Compliant OCAs for High Ink-step Coverage and Mura-free Assembly of LCD Panels 946.3.5 Reworkable OCAs 1026.3.6 Barrier Adhesives 1036.4 Summary and Remaining Challenges 1047 Self-healing Polymer Substrates 107Progyateg Chakma, Zachary A. Digby, and Dominik Konkolewicz7.1 Introduction 1077.2 General Classes of Self-healing Polymers 1087.2.1 Types of Dynamic Bonds in Self-healing Polymers 1097.2.2 Supramolecularly Crosslinked Self-healing Polymers 1097.2.2.1 Hydrogen Bonding 1107.2.2.2 π–π Stacking 1107.2.2.3 Ionic Interactions 1117.2.3 Dynamic-covalently Crosslinked Self-healing Polymers 1117.2.3.1 Cycloaddition Reactions 1117.2.3.2 Disulfides-based Reversible Reactions 1127.2.3.3 Acylhydrazones 1137.2.3.4 Boronate Esters 1137.3 Special Considerations for Flexible Self-healing Polymers 1147.4 Incorporation of Electrically Conductive Components 1157.4.1 Metallic Conductors 1157.4.2 Conductive Polymers 1167.4.3 Carbon Materials 1187.4.4 Polymerized Ionic Liquids 1197.5 Additional Possibilities Enabled by Three-dimensional Printing 1197.6 Concluding Remarks 1218 Flexible Glass Substrates 129Armin Plichta, Andreas Habeck, Silke Knoche, Anke Kruse, Andreas Weber, and Norbert Hildebrand8.1 Introduction 1298.2 Display Glass Properties 1298.2.1 Overview of Display Glass Types 1298.2.2 Glass Properties 1308.2.2.1 Optical Properties 1308.2.2.2 Chemical Properties 1308.2.2.3 Thermal Properties 1318.2.2.4 Surface Properties 1328.2.2.5 Permeability 1338.3 Manufacturing of Thin “Flexible’’ Glass 1348.3.1 Float and Downdraw Technology for Special Glass 1348.3.2 Limits 1358.3.2.1 Thickness Limits for Production 1358.3.2.2 Surface Quality Limits for Production 1368.4 Mechanical Properties 1378.4.1 Thin Glass and Glass/Plastic Substrates 1378.4.2 Mechanical Test Methods for Flexible Glasses 1378.5 Improvement in Mechanical Properties of Glass 1408.5.1 Reinforcement of Glass Substrates 1408.5.1.1 Principal Methods of Reinforcement 1418.5.1.2 Materials for Reinforcement Coatings 1418.6 Processing of Flexible Glass 1428.6.1 Cleaning 1438.6.2 Separation 1438.7 Current Thin Glass Substrate Applications and Trends 1448.7.1 Displays 1458.7.2 Touch Panels 1458.7.3 Sensors 1458.7.4 Wafer-level Chip Size Packaging 1469 Toward a Foldable Organic Light-emitting Diode Display 149Meng-Ting Lee, Chi-Shun Chan, Yi-Hong Chen, Chun-Yu Lin, Annie Tzuyu Huang, Jonathan HT Tao, and Chih-Hung Wu9.1 Panel Stack-up Comparison: Glass-based and Plastic-based Organic Light-emitting Diode 1499.1.1 Technology for Improving Contrast Ratio of OLED Display 1519.2 CF–OLED for Achieving Foldable OLED Display 1539.2.1 Mechanism of the AR coating in CF–OLED 1549.2.2 Optical Performance of CF–OLED 1559.3 Mechanical Performance of CF–OLED 1579.3.1 Bi-directional Folding Performance and Minimum Folding Radius of SPS Cf–oled 1599.4 Touch Panel Technology of CF–OLED 1609.5 Foldable Application 1629.5.1 Foldable Technology Summary 1629.5.1.1 Polymer Substrates and Related Debonding Technology 1629.5.1.2 Alternative TFT Types to LTPS 1629.5.1.3 Encapsulation Systems to Protect Devices against Moisture 1639.5.2 Novel and Next-generation Display Technologies 16310 Flexible Reflective Display Based on Cholesteric Liquid Crystals 167Deng-Ke Yang, J. W. Shiu, M. H. Yang, and Janglin Che10.1 Introduction to Cholesteric Liquid Crystal 16710.2 Reflection of CLC 16910.3 Bistable CLC Reflective Display 17110.4 Color Design of Reflective Bistable CLC Display 17310.4.1 Mono-color Display 17310.4.2 Full-color Display 17310.5 Transitions between Cholesteric States 17510.5.1 Transition from Planar State to Focal Conic State 17510.5.2 Transition from Focal Conic State to Homeotropic State 17710.5.3 Transition from Homotropic State to Focal Conic State 17710.5.4 Transition from Homeotropic State to Transient Planar State 17810.5.5 Transition from Transient Planar State to Planar State 17910.6 Driving Schemes 18110.6.1 Response to Voltage Pulse 18110.6.2 Conventional Driving Scheme 18310.6.3 Dynamic Driving Scheme 18310.6.4 Thermal Driving Scheme 18510.6.5 Flow Driving Scheme 18610.7 Flexible Bistable CLC Reflective Display 18710.8 Bistable Encapsulated CLC Reflective Display 18810.9 Production of Flexible CLC Reflective Displays 18910.9.1 Color e-Book with Single-layered Structure 19110.9.2 Roll-to Roll E-paper and Applications 19510.10 Conclusion 20211 Electronic Paper 207Guofu Zhou, Alex Henzen, and Dong Yuan11.1 Introduction 20711.2 Electrophoretic Display 21011.2.1 Development History and Working Principle 21011.2.2 Materials 21211.2.2.1 Colored Particles/Pigments 21211.2.2.2 Capsule Shell Materials 21311.2.2.3 Suspending Medium (Mobile Phase) 21311.2.2.4 Charge Control Agents 21311.2.2.5 Stabilizers 21311.2.3 Device Fabrication 21411.2.4 Flexible EPD 21511.3 Electrowetting Displays 21611.3.1 Development History and Working Principle 21611.3.2 Materials 21811.3.2.1 Absorbing (Dyed) Hydrophobic Liquid 21811.3.3 Device Fabrication 22011.3.4 Flexible EWD 22111.4 Other E-paper Display Technologies and Feasibility of Flexibility 22211.4.1 Pcd 22211.4.2 Lpd 22311.5 Cholesteric (Chiral Nematic) LCDs 22411.6 Electrochromic Displays 22411.7 MEMS Displays 22612 Encapsulation of Flexible Displays: Background, Status, and Perspective 229Lorenza Moro and Robert Jan Visser12.1 Introduction 22912.2 Background 23012.3 Multilayer TFE Technology 23412.3.1 Multilayer Approach 23412.3.2 Inorganic Layer Deposition Techniques 23712.3.3 Organic Layer Deposition Techniques 23812.4 Current Technology Implementation 24212.5 Future Developments 24612.6 Conclusions 249Acknowledgments 25013 Flexible Battery Fundamentals 255Nicholas Winch, Darran R. Cairns, and Konstantinos A. Sierros13.1 Introduction 25513.2 Structural and Materials Aspects 25613.2.1 Shape 25713.2.2 One-dimensional Batteries 25713.2.3 Two-dimensional Planar Batteries 25813.2.4 Solid versus Liquid Electrolyte 25913.2.5 Carbon Additives 25913.3 Examples of Flexible Batteries 26013.4 Future Perspectives 26614 Flexible and Large-area X-ray Detectors 271Gerwin Gelinck14.1 Introduction 27114.2 Direct and Indirect Detectors 27214.3 Thin-film Photodiode Sensors for Indirect-conversion Detectors 27314.3.1 Performance Parameters 27314.3.2 Photodiode Materials on Plastic Substrates 27514.3.2.1 Amorphous Silicon 27514.3.2.2 Organic Semiconductor Materials 27514.4 TFT Array 27714.4.1 Pixel Architecture and Transistor Requirements 27714.4.2 Flexible Transistor Arrays 27814.5 Medical-grade Detector 28214.6 Summary and Outlook 28315 Interacting with Flexible Displays 287Darran R. Cairns and Anthony S. Weiss15.1 Introduction 28715.2 Touch Technologies in Non-Flexible Displays 28715.2.1 Resistive Touch Sensors 28715.2.2 4-Wire Resistive 28815.2.3 5-Wire Resistive 28915.2.4 Capacitive Sensing 29015.2.5 Surface Capacitive 29115.2.6 Projected Capacitive 29115.2.7 Infrared Sensing 29315.2.8 Surface Acoustic Wave 29315.2.9 Bending Wave Technologies 29415.3 Touch Technologies in Flexible Displays 29415.4 Summary 29916 Mechanical Durability of Inorganic Films on Flexible Substrates 301Yves Leterrier16.1 Introduction 30116.2 Flexible Display Materials 30216.2.1 Property Contrast between Coating and Substrate Materials 30216.2.2 Determination of Mechanical Properties of Inorganic Coatings 30216.3 Stress and Strain Analyses 30416.3.1 Intrinsic, Thermal, and Hygroscopic Stresses and Strains 30416.3.2 Strain Analysis of Multilayer Films under Bending 30716.3.3 Critical Radius of Curvature 30816.4 Failure Mechanics of Brittle Films 30916.4.1 Damage Phenomenology under Tensile and Compressive Loading 30916.4.2 Experimental Methods 31016.4.3 Fracture Mechanics Analysis 31116.4.4 Role of Internal Stresses 31216.4.5 Influence of Film Thickness on Critical Strain 31216.5 Durability Influences 31316.5.1 Influence of Temperature 31316.5.2 Fatigue 31416.5.3 Corrosion 31516.6 Toward Robust Layers 31716.7 Final Remarks 317Acknowledgments 318Nomenclature 31817 Roll-to-roll Production Challenges for Large-area Printed Electronics 325Dr. Grzegorz Andrzej Potoczny17.1 Introduction 32517.2 Infrastructure 32717.3 Equipment 32817.4 Materials 32917.5 Processing 33117.6 Summary 33418 Direct Ink Writing of Touch Sensors and Displays: Current Developments and Future Perspectives 337Konstantinos A. Sierros and Darran R. Cairns18.1 Introduction 33718.2 DIW and Ink Development 33818.3 Applications of DIW for Displays and Touch Sensors 34318.4 Future Challenges and Opportunities 34719 Flexible Displays for Medical Applications 351Uwadiae Obahiagbon, Karen S. Anderson, and Jennifer M. Blain Christen19.1 Introduction 35119.1.1 Flexible Displays in Medicine 35119.1.2 A Brief Historical Perspective 35119.1.3 Application of Flexible Displays for Biochemical Analysis 35219.1.4 OLEDs and Organic Photodiodes as Optical Excitation Sources and Detectors 35219.1.5 Device Integration 35419.1.6 Fluorescence, Photoluminescence Intensity, and Decay-time Sensing 35519.2 Flexible OLEDs for Oxygen Sensors 35619.3 Glucose Sensing Using Flexible Display Technology 35819.4 POC Disease Diagnosis and Pathogen Detection Using Flexible Display Optoelectronics 35919.5 Flexible Display Technology for Multi-analyte Sensor Array Platforms 36419.5.1 Integrated LOC and Flexible Display Devices 36419.5.2 Multiplexed Sensor Platforms 36419.6 Medical Diagnostic Displays 36619.7 Wearable Health Monitoring Devices Based on Flexible Displays 36619.7.1 Monitoring Vital Signs Using Flexible Display Technology 36719.7.2 Flexible Display Technology for Phototherapy 36919.7.3 Smart Clothing Using Flexible Display Technology 37019.8 Competing Technologies, Challenges, and Future Trends 37119.9 Conclusion 372Acknowledgment 373Conflicts of Interest 373Index 379