Flexible Flat Panel Displays
A complete treatment of the entire lifecycle of flexible flat panel displays, from raw material selection to commercialization
In the newly revised Second Edition of Flexible Flat Panel Displays, a distinguished team of researchers delivers a completely restructured and comprehensive treatment of the field of flexible flat panel displays. With material covering the end-to-end process that includes commercial and technical aspects of the technology, the editors have included contributions that introduce the business, marketing, entrepreneurship, and intellectual property content relevant to flexible flat panel displays.
This edited volume contains a brand-new section on case studies using the Harvard Business School format that discusses current and emerging markets in flexible displays, such as an examination of the use of electronic ink and QD Vision in commercial devices.
From raw material selection to device prototyping, manufacturing, and commercialization, each stage of the flexible display business is discussed in this insightful new edition. The book also includes:
- Thorough introductions to engineered films for display technology and liquid crystal optical coatings for flexible displays
- Comprehensive explorations of organic TFT foils, metallic nanowires, adhesives, and self-healing polymer substrates
- Practical discussions of flexible glass, AMOLEDs, cholesteric displays, and electronic paper
- In-depth examinations of the encapsulation of flexible displays, flexible batteries, flexible flat panel photodetectors, and flexible touch screens
Perfect for professionals working in the field of display technology with backgrounds in science and engineering, Flexible Flat Panel Displays is also an indispensable resource for professionals with marketing, sales, and technology backgrounds, as well as senior undergraduates and graduate students in engineering and materials science.
Table of Contents
Series Editor’s Foreword xv
List of Contributors xvii
1 Introduction 1
Darran R. Cairns, Gregory P. Crawford, and Dirk J. Broer
1.1 Toward Flexible Mobile Devices 1
1.2 Flexible Display Layers 2
1.3 Other Flexible Displays and Manufacturing 2
2 Engineered Films for Display Technology 5
W.A. MacDonald
2.1 Introduction 5
2.2 Factors Influencing Film Choice 5
2.2.1 Application Area 5
2.2.2 Physical Form/Manufacturing Process 6
2.2.3 Film Property Set 7
2.2.3.1 Polymer Type 7
2.2.3.2 Optical Clarity 9
2.2.3.3 Birefringence 10
2.2.3.4 The Effect of Thermal Stress on Dimensional Reproducibility 10
2.2.3.5 Low-bloom Films 11
2.2.3.6 Solvent and Moisture Resistance 12
2.2.3.7 The Effect of Mechanical Stress on Dimensional Reproducibility 16
2.2.3.8 Surface Quality 18
2.3 Summary of Key Properties of Base Substrates 19
2.4 Planarizing Coatings 21
2.5 Examples of Film in Use 23
2.6 Concluding Remarks 24
Acknowledgments 25
3 Liquid Crystal Optical Coatings for Flexible Displays 27
Owain Parri, Johan Lub, and Dirk J. Broer
3.1 Introduction 27
3.2 LCN Technology 27
3.3 Thin-film Polarizers 29
3.3.1 Smectic Polarizers 29
3.3.2 Cholesteric Polarizers 32
3.4 Thin-film Retarders 34
3.4.1 Reactive Mesogen Retarders 35
3.4.2 Chromonic Liquid Crystal-based Retarders 37
3.4.3 Liquid Crystal Alignment and Patterned Retarders 37
3.5 Color Filters 41
3.6 Conclusion 43
4 Large Area Flexible Organic Field-effect Transistor Fabrication 47
Zachary A. Lamport, Marco Roberto Cavallari, and Ioannis Kymissis
4.1 Introduction 47
4.2 Substrates 48
4.3 Photolithography 49
4.4 Printing for Roll-to-roll Fabrication 52
4.4.1 Inkjet Printing 52
4.4.2 Gravure and Flexographic Printing 55
4.4.3 Screen Printing 56
4.4.4 Aerosol Jet Printing 56
4.4.5 Contact Printing 58
4.4.6 Meniscus Dragging 60
4.5 Conclusions 62
5 Metallic Nanowires, Promising Building Nanoblocks for Flexible Transparent Electrodes 67
Jean-Pierre Simonato
5.1 Introduction 67
5.2 TEs Based on Metallic Nanowires 68
5.2.1 Metallic Nanowires, New Building Nanoblocks 68
5.2.2 Random Network Fabrication 69
5.2.3 Optical Characterization 70
5.2.4 Electrical Characterization 71
5.2.5 Mechanical Aspect 73
5.3 Application to Flexible Displays 73
5.3.1 Touch Screens 73
5.3.2 Light-emitting Diodes Displays 74
5.3.3 Electrochromic Flexible Displays 76
5.3.4 Other Displays 77
5.4 Conclusions 78
6 Optically Clear Adhesives for Display Assembly 85
Albert I. Everaerts
6.1 Introduction 85
6.2 OCA Definition and General Performance Specifications 86
6.3 Application Examples and Challenges 89
6.3.1 Outgassing Tolerant Adhesives 90
6.3.2 Anti-whitening Adhesives 91
6.3.3 Non-corrosive OCAs 92
6.3.4 Compliant OCAs for High Ink-step Coverage and Mura-free Assembly of LCD Panels 94
6.3.5 Reworkable OCAs 102
6.3.6 Barrier Adhesives 103
6.4 Summary and Remaining Challenges 104
7 Self-healing Polymer Substrates 107
Progyateg Chakma, Zachary A. Digby, and Dominik Konkolewicz
7.1 Introduction 107
7.2 General Classes of Self-healing Polymers 108
7.2.1 Types of Dynamic Bonds in Self-healing Polymers 109
7.2.2 Supramolecularly Crosslinked Self-healing Polymers 109
7.2.2.1 Hydrogen Bonding 110
7.2.2.2 π-π Stacking 110
7.2.2.3 Ionic Interactions 111
7.2.3 Dynamic-covalently Crosslinked Self-healing Polymers 111
7.2.3.1 Cycloaddition Reactions 111
7.2.3.2 Disulfides-based Reversible Reactions 112
7.2.3.3 Acylhydrazones 113
7.2.3.4 Boronate Esters 113
7.3 Special Considerations for Flexible Self-healing Polymers 114
7.4 Incorporation of Electrically Conductive Components 115
7.4.1 Metallic Conductors 115
7.4.2 Conductive Polymers 116
7.4.3 Carbon Materials 118
7.4.4 Polymerized Ionic Liquids 119
7.5 Additional Possibilities Enabled by Three-dimensional Printing 119
7.6 Concluding Remarks 121
8 Flexible Glass Substrates 129
Armin Plichta, Andreas Habeck, Silke Knoche, Anke Kruse, Andreas Weber, and Norbert Hildebrand
8.1 Introduction 129
8.2 Display Glass Properties 129
8.2.1 Overview of Display Glass Types 129
8.2.2 Glass Properties 130
8.2.2.1 Optical Properties 130
8.2.2.2 Chemical Properties 130
8.2.2.3 Thermal Properties 131
8.2.2.4 Surface Properties 132
8.2.2.5 Permeability 133
8.3 Manufacturing of Thin “Flexible’’ Glass 134
8.3.1 Float and Downdraw Technology for Special Glass 134
8.3.2 Limits 135
8.3.2.1 Thickness Limits for Production 135
8.3.2.2 Surface Quality Limits for Production 136
8.4 Mechanical Properties 137
8.4.1 Thin Glass and Glass/Plastic Substrates 137
8.4.2 Mechanical Test Methods for Flexible Glasses 137
8.5 Improvement in Mechanical Properties of Glass 140
8.5.1 Reinforcement of Glass Substrates 140
8.5.1.1 Principal Methods of Reinforcement 141
8.5.1.2 Materials for Reinforcement Coatings 141
8.6 Processing of Flexible Glass 142
8.6.1 Cleaning 143
8.6.2 Separation 143
8.7 Current Thin Glass Substrate Applications and Trends 144
8.7.1 Displays 145
8.7.2 Touch Panels 145
8.7.3 Sensors 145
8.7.4 Wafer-level Chip Size Packaging 146
9 Toward a Foldable Organic Light-emitting Diode Display 149
Meng-Ting Lee, Chi-Shun Chan, Yi-Hong Chen, Chun-Yu Lin, Annie Tzuyu Huang, Jonathan HT Tao, and Chih-Hung Wu
9.1 Panel Stack-up Comparison: Glass-based and Plastic-based Organic Light-emitting Diode 149
9.1.1 Technology for Improving Contrast Ratio of OLED Display 151
9.2 CF-OLED for Achieving Foldable OLED Display 153
9.2.1 Mechanism of the AR coating in CF-OLED 154
9.2.2 Optical Performance of CF-OLED 155
9.3 Mechanical Performance of CF-OLED 157
9.3.1 Bi-directional Folding Performance and Minimum Folding Radius of SPS Cf-oled 159
9.4 Touch Panel Technology of CF-OLED 160
9.5 Foldable Application 162
9.5.1 Foldable Technology Summary 162
9.5.1.1 Polymer Substrates and Related Debonding Technology 162
9.5.1.2 Alternative TFT Types to LTPS 162
9.5.1.3 Encapsulation Systems to Protect Devices against Moisture 163
9.5.2 Novel and Next-generation Display Technologies 163
10 Flexible Reflective Display Based on Cholesteric Liquid Crystals 167
Deng-Ke Yang, J. W. Shiu, M. H. Yang, and Janglin Che
10.1 Introduction to Cholesteric Liquid Crystal 167
10.2 Reflection of CLC 169
10.3 Bistable CLC Reflective Display 171
10.4 Color Design of Reflective Bistable CLC Display 173
10.4.1 Mono-color Display 173
10.4.2 Full-color Display 173
10.5 Transitions between Cholesteric States 175
10.5.1 Transition from Planar State to Focal Conic State 175
10.5.2 Transition from Focal Conic State to Homeotropic State 177
10.5.3 Transition from Homotropic State to Focal Conic State 177
10.5.4 Transition from Homeotropic State to Transient Planar State 178
10.5.5 Transition from Transient Planar State to Planar State 179
10.6 Driving Schemes 181
10.6.1 Response to Voltage Pulse 181
10.6.2 Conventional Driving Scheme 183
10.6.3 Dynamic Driving Scheme 183
10.6.4 Thermal Driving Scheme 185
10.6.5 Flow Driving Scheme 186
10.7 Flexible Bistable CLC Reflective Display 187
10.8 Bistable Encapsulated CLC Reflective Display 188
10.9 Production of Flexible CLC Reflective Displays 189
10.9.1 Color e-Book with Single-layered Structure 191
10.9.2 Roll-to Roll E-paper and Applications 195
10.10 Conclusion 202
11 Electronic Paper 207
Guofu Zhou, Alex Henzen, and Dong Yuan
11.1 Introduction 207
11.2 Electrophoretic Display 210
11.2.1 Development History and Working Principle 210
11.2.2 Materials 212
11.2.2.1 Colored Particles/Pigments 212
11.2.2.2 Capsule Shell Materials 213
11.2.2.3 Suspending Medium (Mobile Phase) 213
11.2.2.4 Charge Control Agents 213
11.2.2.5 Stabilizers 213
11.2.3 Device Fabrication 214
11.2.4 Flexible EPD 215
11.3 Electrowetting Displays 216
11.3.1 Development History and Working Principle 216
11.3.2 Materials 218
11.3.2.1 Absorbing (Dyed) Hydrophobic Liquid 218
11.3.3 Device Fabrication 220
11.3.4 Flexible EWD 221
11.4 Other E-paper Display Technologies and Feasibility of Flexibility 222
11.4.1 Pcd 222
11.4.2 Lpd 223
11.5 Cholesteric (Chiral Nematic) LCDs 224
11.6 Electrochromic Displays 224
11.7 MEMS Displays 226
12 Encapsulation of Flexible Displays: Background, Status, and Perspective 229
Lorenza Moro and Robert Jan Visser
12.1 Introduction 229
12.2 Background 230
12.3 Multilayer TFE Technology 234
12.3.1 Multilayer Approach 234
12.3.2 Inorganic Layer Deposition Techniques 237
12.3.3 Organic Layer Deposition Techniques 238
12.4 Current Technology Implementation 242
12.5 Future Developments 246
12.6 Conclusions 249
Acknowledgments 250
13 Flexible Battery Fundamentals 255
Nicholas Winch, Darran R. Cairns, and Konstantinos A. Sierros
13.1 Introduction 255
13.2 Structural and Materials Aspects 256
13.2.1 Shape 257
13.2.2 One-dimensional Batteries 257
13.2.3 Two-dimensional Planar Batteries 258
13.2.4 Solid versus Liquid Electrolyte 259
13.2.5 Carbon Additives 259
13.3 Examples of Flexible Batteries 260
13.4 Future Perspectives 266
14 Flexible and Large-area X-ray Detectors 271
Gerwin Gelinck
14.1 Introduction 271
14.2 Direct and Indirect Detectors 272
14.3 Thin-film Photodiode Sensors for Indirect-conversion Detectors 273
14.3.1 Performance Parameters 273
14.3.2 Photodiode Materials on Plastic Substrates 275
14.3.2.1 Amorphous Silicon 275
14.3.2.2 Organic Semiconductor Materials 275
14.4 TFT Array 277
14.4.1 Pixel Architecture and Transistor Requirements 277
14.4.2 Flexible Transistor Arrays 278
14.5 Medical-grade Detector 282
14.6 Summary and Outlook 283
15 Interacting with Flexible Displays 287
Darran R. Cairns and Anthony S. Weiss
15.1 Introduction 287
15.2 Touch Technologies in Non-Flexible Displays 287
15.2.1 Resistive Touch Sensors 287
15.2.2 4-Wire Resistive 288
15.2.3 5-Wire Resistive 289
15.2.4 Capacitive Sensing 290
15.2.5 Surface Capacitive 291
15.2.6 Projected Capacitive 291
15.2.7 Infrared Sensing 293
15.2.8 Surface Acoustic Wave 293
15.2.9 Bending Wave Technologies 294
15.3 Touch Technologies in Flexible Displays 294
15.4 Summary 299
16 Mechanical Durability of Inorganic Films on Flexible Substrates 301
Yves Leterrier
16.1 Introduction 301
16.2 Flexible Display Materials 302
16.2.1 Property Contrast between Coating and Substrate Materials 302
16.2.2 Determination of Mechanical Properties of Inorganic Coatings 302
16.3 Stress and Strain Analyses 304
16.3.1 Intrinsic, Thermal, and Hygroscopic Stresses and Strains 304
16.3.2 Strain Analysis of Multilayer Films under Bending 307
16.3.3 Critical Radius of Curvature 308
16.4 Failure Mechanics of Brittle Films 309
16.4.1 Damage Phenomenology under Tensile and Compressive Loading 309
16.4.2 Experimental Methods 310
16.4.3 Fracture Mechanics Analysis 311
16.4.4 Role of Internal Stresses 312
16.4.5 Influence of Film Thickness on Critical Strain 312
16.5 Durability Influences 313
16.5.1 Influence of Temperature 313
16.5.2 Fatigue 314
16.5.3 Corrosion 315
16.6 Toward Robust Layers 317
16.7 Final Remarks 317
Acknowledgments 318
Nomenclature 318
17 Roll-to-roll Production Challenges for Large-area Printed Electronics 325
Dr. Grzegorz Andrzej Potoczny
17.1 Introduction 325
17.2 Infrastructure 327
17.3 Equipment 328
17.4 Materials 329
17.5 Processing 331
17.6 Summary 334
18 Direct Ink Writing of Touch Sensors and Displays: Current Developments and Future Perspectives 337
Konstantinos A. Sierros and Darran R. Cairns
18.1 Introduction 337
18.2 DIW and Ink Development 338
18.3 Applications of DIW for Displays and Touch Sensors 343
18.4 Future Challenges and Opportunities 347
19 Flexible Displays for Medical Applications 351
Uwadiae Obahiagbon, Karen S. Anderson, and Jennifer M. Blain Christen
19.1 Introduction 351
19.1.1 Flexible Displays in Medicine 351
19.1.2 A Brief Historical Perspective 351
19.1.3 Application of Flexible Displays for Biochemical Analysis 352
19.1.4 OLEDs and Organic Photodiodes as Optical Excitation Sources and Detectors 352
19.1.5 Device Integration 354
19.1.6 Fluorescence, Photoluminescence Intensity, and Decay-time Sensing 355
19.2 Flexible OLEDs for Oxygen Sensors 356
19.3 Glucose Sensing Using Flexible Display Technology 358
19.4 POC Disease Diagnosis and Pathogen Detection Using Flexible Display Optoelectronics 359
19.5 Flexible Display Technology for Multi-analyte Sensor Array Platforms 364
19.5.1 Integrated LOC and Flexible Display Devices 364
19.5.2 Multiplexed Sensor Platforms 364
19.6 Medical Diagnostic Displays 366
19.7 Wearable Health Monitoring Devices Based on Flexible Displays 366
19.7.1 Monitoring Vital Signs Using Flexible Display Technology 367
19.7.2 Flexible Display Technology for Phototherapy 369
19.7.3 Smart Clothing Using Flexible Display Technology 370
19.8 Competing Technologies, Challenges, and Future Trends 371
19.9 Conclusion 372
Acknowledgment 373
Conflicts of Interest 373
Index 379
