List of Contributors XV
Overview XXIII
Part I: Materials 1
1 Polymeric and Small-Molecule Semiconductors for Organic Field-Effect Transistors 3
Hakan Usta and Antonio Facchetti
1.1 Introduction 3
1.2 Organic Semiconductor Structural Design 3
1.3 Thin-Film Transistor Applications 6
1.4 p-Channel Semiconductors 8
1.4.1 Polymers 8
1.4.2 Small Molecules 26
1.5 n-Channel Semiconductors 37
1.5.1 Polymers 37
1.5.2 Small Molecules 51
1.6 Ambipolar Semiconductors 68
1.6.1 Polymers 69
1.6.2 Small Molecules 77
1.7 Conclusions 85
References 85
2 Metal-Oxide Thin-Film Transistors for Flexible Electronics 101
Yong-Hoon Kimand Sung Kyu Park
2.1 Introduction 101
2.2 Metal-Oxide TFTs 102
2.2.1 Advantages and Applications 102
2.2.2 Vacuum Deposition 102
2.2.3 Solution Processing 103
2.3 Solution-Processed MOThin Films 103
2.3.1 Nanoparticle-Based Process 103
2.3.2 Solâ"Gel-Based Process 104
2.3.3 Hybrid Type 105
2.4 Low-Temperature-Processed MO TFTs for Flexible Electronics 105
2.4.1 Low-Temperature-Processed MO TFTs 106
2.4.1.1 Annealing Environment 106
2.4.1.2 Ink Formulation 106
2.4.1.3 Alternate Annealing Process 107
2.4.2 Photochemical Activation of Oxide Semiconductors 107
2.5 Summary 114
References 115
3 Carbon Nanotube Thin-Film Transistors 117
Taishi Takenobu
3.1 Introduction 117
3.2 Individual SWCNTs and SWCNT Thin Films 118
3.3 Chemical Vapor Deposition Growth of SWCNT TFTs 118
3.4 Solution-Based Methods for SWCNT TFTs 120
3.5 Inkjet Printing of Flexible SWCNT TFTs 120
3.6 Fabrication Schemes for High-Performance Inkjet-Printed SWCNT TFTs 122
3.7 Inkjet Printing of SWCNT CMOS Inverters 124
3.8 Inkjet Printing of Aligned SWCNT Films 128
3.9 Conclusion 129
References 129
4 Organic Single-Crystalline Semiconductors for Flexible Electronics Applications 133
Marcos A. Reyes-Martinez, Nicholas S. Colella, and Alejandro L. Briseno
4.1 Introduction 133
4.2 Electronic and Structural Properties of Single Crystals 134
4.2.1 Intrinsic Transport Properties 135
4.2.2 Crystal Dimensionality 136
4.3 Crystallization Techniques 138
4.3.1 Growth from Vapor Phase 138
4.3.2 Growth from Solution 138
4.4 Single-Crystal Flexible Electronic Devices 139
4.4.1 Fundamental Mechanics for Flexible Electronics 139
4.4.2 Mechanical Versatility of Organic Single Crystals 141
4.4.3 Importance of Mechanical Properties Knowledge 142
4.4.4 The Elastic Constants of Rubrene Single Crystals 144
4.5 Strategies for Flexible Organic Single-Crystal Device Fabrication 149
4.5.1 Discrete Ultrathin Single-Crystal Transistor 150
4.5.2 Transistor Arrays Based on Micropatterned Single Crystals 150
4.5.3 Flexible Single-Crystal Nanowire Devices 156
4.6 Conclusions 158
Acknowledgments 159
References 159
5 Solution-Processable Quantum Dots 163
Hongbo Li, Vladimir Lesnyak, and Liberato Manna
5.1 Introduction 163
5.2 Optimization of the Colloidal Synthesis of Quantum Dots by Selection of Suitable Solvents, Ligands, and Precursors 164
5.3 Large-Scale Synthesis of Quantum Dots 166
5.4 Surface Chemistry of Quantum Dots 169
5.5 Post-Synthetic Chemical Modification of Nanocrystals 174
5.6 Conclusions and Outlook 179
References 179
6 Inorganic Semiconductor Nanomaterials for Flexible Electronics 187
Houk Jang,Wonho Lee,Min-Soo Kim, and Jong-Hyun Ahn
6.1 Introduction 187
6.2 Characteristics and Synthesis of Inorganic Semiconducting NMs 188
6.2.1 Characteristics of Inorganic NMs 188
6.2.1.1 Mechanical Properties of Inorganic NMs in Bending and Stretching 188
6.2.1.2 Optoelectrical Properties 191
6.2.2 Fabrication of Inorganic NMs for Flexible Electronics 193
6.2.2.1 Selective Etching 193
6.2.2.2 Anisotropic Etching 194
6.2.2.3 Mass Production of Inorganic NMs 195
6.2.2.4 Transfer Process 197
6.3 Applications in Flexible Electronics 198
6.3.1 Flexible Electronics 198
6.3.1.1 Flexible Solar Cell 198
6.3.1.2 Flexible Memory 201
6.3.1.3 Flexible High-Frequency Transistor 202
6.3.1.4 Foldable Transistor Using Ultrathin Si NMs 203
6.3.2 Conformal Device 205
6.3.2.1 Conformal Biomonitoring System 206
6.3.3 Stretchable Electronics 207
6.3.3.1 Stretchable Logic Circuit 207
6.3.3.2 Stretchable Light-Emitting Diode 211
6.3.3.3 Photodetector 211
6.3.4 Utilizing Deformation of NMs 215
6.3.4.1 Nanogenerator and Actuator 217
6.3.4.2 RF Device Using Strained NMs 218
6.3.5 Transparent Transistor 219
6.4 Concluding Remarks 221
References 221
7 Dielectric Materials for Large-Area and Flexible Electronics 225
Sungjun Park, Sujin Sung,Won-June Lee, andMyung-Han Yoon
7.1 Introduction 225
7.2 General Polymer Dielectrics 226
7.3 Cross-Linked Polymer Dielectrics 227
7.4 High-k Polymer Dielectrics 228
7.5 Electrolyte Gate Dielectrics 230
7.6 Self-Assembled Molecular Layer Dielectrics 234
7.7 Hybrid Dielectrics 237
7.7.1 Organicâ"Inorganic Laminated Bilayers/Multilayers 237
7.7.2 Organic Polymeric/Inorganic Nanoparticle and Nanocomposites 238
7.7.3 Hybrid Dielectrics Based on Organosiloxane and Organozirconia 240
7.8 Solâ"Gel High-k Inorganic Dielectrics 243
7.9 Summary and Outlook 246
References 247
8 Electrolyte-Gating Organic Thin Film Transistors 253
Moon Sung Kang, Jeong Ho Cho, and Se Hyun Kim
8.1 Introduction 253
8.2 Electrolyte-Gated OTFT OperationMechanisms 255
8.3 Electrolyte Materials 257
8.4 OTFTs Gated with Electrolyte Dielectrics 260
8.5 Circuits Based on Electrolyte-Gated OTFTs 263
8.6 Conclusions 267
References 267
9 Vapor Barrier Films for Flexible Electronics 275
Seok-Ju Kang, Chuan Liu, and Yong-Young Noh
9.1 Introduction 275
9.2 Thin-Film Permeation Barrier Layers 277
9.3 Permeation through Inorganic Thin Films 280
9.4 Time-Resolved Measurements on Barrier Layers 283
9.5 Mechanical Limitations of Inorganic Films 284
9.6 Mechanics of Films on Flexible Substrates 284
9.7 Summary 286
References 287
10 Latest Advances in Substrates for Flexible Electronics 291
William A. MacDonald
10.1 Introduction 291
10.2 Factors Influencing Film Choice 292
10.2.1 Application Area 292
10.2.2 Physical Form/Manufacturing Process 292
10.3 Film Property Set 293
10.3.1 Polymer Type 293
10.3.2 Optical Clarity 295
10.3.3 Birefringence 296
10.3.4 The Effect of Thermal Stress on Dimensional Reproducibility 296
10.3.5 Cyclic Oligomers 298
10.3.6 Solvent and Moisture Resistance 299
10.3.7 The Effect of Mechanical Stress on Dimensional Reproducibility 302
10.3.8 Surface Quality 303
10.3.8.1 Inherent Surface Smoothness 303
10.3.8.2 Surface Cleanliness 305
10.4 Summary of Key Properties of Base Substrates 306
10.5 Planarizing Coatings 308
10.6 Examples of Film in Use 310
10.7 Concluding Remarks 312
Acknowledgments 312
References 312
Part II: Devices and Applications 315
11 Inkjet Printing Process for Large Area Electronics 317
Sungjune Jung, Steve D. Hoath, Graham D. Martin, and Ian M. Hutchings
11.1 Introduction 317
11.2 Dynamics of Jet Formation 318
11.3 Ink Rheology: Non-Newtonian Liquids 322
11.4 Dynamics of Drop Impact and Spreading 327
11.5 Applications of Inkjet Printing for Large-Area Electronics 333
11.5.1 Light-Emitting Diodes 333
11.5.2 Thin-Film Transistors 335
11.5.3 Solar Cells 339
11.6 Summary 340
References 341
12 Inkjet-Printed Electronic Circuits Based on Organic Semiconductors 345
Kang-Jun Baeg and Yong-Young Noh
12.1 Printed Organic Electronics 345
12.1.1 Printed Electronic Devices 345
12.1.2 Inkjet Printing Technology 347
12.2 CMOS Technology 349
12.2.1 CMOS Inverters 350
12.2.2 Ring Oscillators 353
12.3 High-Speed Organic CMOS Circuits 355
12.3.1 High-Mobility Printable Semiconductors 356
12.3.2 Downscaling of Channel Length 358
12.3.3 Reducing Contact Resistance 359
12.3.4 Reducing Parasitic Overlap Capacitance 359
12.4 Conclusions 361
References 362
13 Large-Area, Printed Organic Circuits for Ambient Electronics 365
Tsuyoshi Sekitani, Tomoyuki Yokota, and Takao Someya
13.1 Introduction 365
13.2 Manufacturing Process and Electrical Characteristics 366
13.2.1 Materials and Methods 366
13.2.2 Organic Transistors Manufactured Using Printing Technologies 366
13.2.2.1 Manufacturing Process for DNTT Transistors 369
13.2.2.2 Electrical Performance of DNTT Transistors 369
13.2.2.3 Manufacturing Process for All-Printed Transistors 369
13.2.2.4 Electrical Performance of All-Printed Transistors 369
13.2.3 Mechanical Characteristics 370
13.2.4 Inverter Circuits and Ring Oscillator Using Printed Transistors 371
13.2.5 Printed Organic Floating-Gate Transistors 371
13.2.5.1 Manufacturing Process 373
13.2.5.2 Electrical Performance 373
13.3 Demonstration 376
13.3.1 Organic Active-Matrix LED Pixel Circuits 376
13.3.2 Large-Area Flexible Pressure Sensor Sheet 376
13.3.3 Intelligent Sensor Catheter for Medical Diagnosis 378
13.4 Future Prospects 378
Acknowledgments 378
References 379
14 Polymer and Organic Nonvolatile Memory Devices 381
Seung-Hoon Lee, Yong Xu, and Yong-Young Noh
14.1 Introduction 381
14.2 Resistive Switching Memories 384
14.2.1 Fundamentals of Resistive Switching Principles 384
14.2.2 Mechanisms of Resistive Switching 386
14.2.2.1 Filamentary Conduction 386
14.2.2.2 Space Charge and Traps 387
14.2.2.3 Charge Transfer 388
14.2.2.4 Ionic Conduction 388
14.2.3 The Role of Ï-Conjugated Material in Switching Process 388
14.2.4 Recent Flexible RRAM Based on Organicâ"Inorganic Bistable Materials 389
14.3 Charge Storage in Transistor Gate Dielectric 390
14.3.1 Operation of Charge-Storage OFET Memory Devices 391
14.3.2 Charge Storage in Polymer Electrets 392
14.3.3 Nanoparticle-Embedded Gate Dielectrics 394
14.4 Polymer Ferroelectric Devices 396
14.4.1 Materials 399
14.4.2 Principles of Memory Operation 401
14.4.2.1 Capacitor 402
14.4.2.2 Field-Effect Transistor 402
14.5 Conclusions 407
References 407
15 Flexible Displays 411
Chung-kun Song and Gi-Seong Ryu
15.1 Introduction 411
15.2 Flexible Substrates 412
15.2.1 Thermal Stability 413
15.2.2 Optical Transparency 414
15.2.3 Permeation of Oxygen and Moisture 414
15.2.4 Chemical Resistance 415
15.2.5 Surface Roughness 415
15.3 Display Mode 415
15.4 Thin-Film Transistor 418
15.4.1 a-Si TFT 419
15.4.2 LTPS TFT 420
15.4.3 Oxide TFT 420
15.4.4 OTFT 422
15.5 AMOLED Panel with Printing Technology 426
15.5.1 Design and Fabrication of OTFT Backplane 426
15.5.2 Screen Printing of the Gate Electrodes and Scan Bus Lines 428
15.5.3 Inkjet Printing of TIPS-Pentacene for OTFTs 431
15.6 Fabrication of the OLED and AMOLED Panel 433
15.7 Future Prospects 435
References 435
16 Flexible Organic Solar Cells for Scalable, Low-Cost Photovoltaic Energy Conversion 439
Seunghyup Yoo, Jongjin Lee, Donggeon Han, and Hoyeon Kim
16.1 Overview of Organic Photovoltaic (OPV) Cells 439
16.1.1 Motivation for OPV Cells 439
16.1.2 Fundamentals of OPV Technologies 441
16.1.2.1 General Operation of PV Cells 441
16.1.2.2 Working Principle of OPV Cells 442
16.1.2.3 Major Components and Various Configuration of OPV Cells 444
16.2 Efforts toward Realization of Flexible OSCs 449
16.2.1 Overview 449
16.2.2 Transparent Electrodes (TEs) for Flexible OSCs 449
16.2.2.1 Metal Grids Combined with Other Transparent Electrodes 450
16.2.2.2 Other Flexible Transparent Electrodes 451
16.2.3 Encapsulation Issues 454
16.3 Flexible OSCs for High-Throughput Production: A Printing-Based Approach to Low-Cost Solar Energy Conversion 455
16.3.1 Printing Technology Overview 455
16.3.2 Review of Printing Technologies Used for OSCs 456
16.3.2.1 Screen Printing 456
16.3.2.2 Droplet Coating and Printing 456
16.3.2.3 Blade/Knife Edge Coating and Slot-Die Printing 458
16.3.2.4 Gravure Printing 460
16.3.2.5 Other Coating/Printing Methods 460
16.3.3 Issues in Module Fabrication 462
16.4 Summary and Outlook 463
References 463
17 Flexible Inorganic Photovoltaics 469
Zhuoying Chen
17.1 Introduction 469
17.2 Thin Crystalline Solar Cells Transferred onto Flexible Substrates 470
17.3 Thin-Film Solar Cells Grown Directly onto Flexible Substrates by Vapor Deposition 472
17.4 Solution-ProcessedThin-Film Solar Cells Deposited Directly onto Flexible Substrates 477
17.5 Summary 480
References 480
18 Scalable and Flexible Bioelectronics and Its Applications to Medicine 485
Salvatore Iannotta, Pasquale DâAngelo, Agostino Romeo, and Giuseppe Tarabella
18.1 Biosensing and Bioelectronics: A Fast Growing Field and a Challenging Research Area 485
18.2 Inorganic and Silicon-Based Flexible Electronics for Biosensing Devices 490
18.2.1 Inorganic Semiconductors for Flexible Electronics: From Hybrids and Inorganic Semiconducting Composites to Silicon 491
18.2.2 Bioapplications: From Cellâ"Silicon Junctions Toward Neuroprosthesis and Neuromedicine 496
18.3 EGOFETs for Flexible Biosensing 507
18.3.1 EGOFET: Architecture,Working Principle, and Materials 508
18.3.2 Biochemical Sensing 512
18.3.3 Interfacing with Neural Tissue 517
18.3.4 Opportunities and Challenges 519
18.4 OECTs for Biosensing and Biomonitoring 520
18.4.1 OECT Architecture andWorking Principle 520
18.4.2 The Applications of OECT as a Biological Sensor 522
18.4.2.1 Drug Nanocarriers for Drug Delivery 522
18.4.2.2 Dopamine and Eumelanin Sensing 523
18.4.2.3 Sensing Cell and Bacterial Activity 526
18.4.2.4 DNA 528
18.4.2.5 Biosensing Toward e-Textile Applications 529
18.4.3 Organic Electronic Ion Pumps (OEIPs) 529
18.5 Conclusions and Outlook 531
References 533
Index 541
