Large Area and Flexible Electronics

Mario Caironi is a Tenure Track Researcher at the Center for Nano Science and Technology (CNST) in Milan, Italy, of the Istituto Italiano di Tecnologia. He obtained his PhD in 2007 from the "Politecnico di Milano" and then joined Prof. Henning Sirringhaus' group at the Cavendish Laboratory in Cambridge, UK, to work on inkjet-printed, downscaled organic field-effect transistors (OFET) and on charge injection and transport in high-mobility polymers. In 2010 he was appointed as a Team Leader at CNST and entered tenure track in 2014 in the same institution.His current research interests are on direct-writing and roll-to-roll printing processes for organic and hybrid micro- and opto-electronics, on the device physics of OFETSs and on organic thermoelectrics. Yong-Young Noh is Associate Professor in the Department of Energy and Materials Engineering at Dongguk University in Seoul, Republic of Korea. He received his PhD in 2005 from the Gwangju Institute of Science and Technology (GIST), Republic of Korea, and then worked at the Cavendish Laboratory in Cambridge, UK, as a postdoctoral associate with Prof. Henning Sirringhaus from 2005 t0 2007. Afterwards, he worked at the Electronics and Telecommunications Research Institute (ETRI), Republic of Korea, as a senior researcher from 2008 to 2009, and at Hanbat National University as assistant professor from 2010 to 2012. Yong-Young Noh has received Merck Young Scientist Award (2013) and Korea President Award (2014). He has expertise in materials, process and device physics of organic and printed electronics for flexible electronics, especially printed OFETs, carbon nanotube or oxide TFTs and OLEDs.

• List of Contributors XVOverview XXIIIPart I: Materials 11 Polymeric and Small-Molecule Semiconductors for Organic Field-Effect Transistors 3Hakan Usta and Antonio Facchetti1.1 Introduction 31.2 Organic Semiconductor Structural Design 31.3 Thin-Film Transistor Applications 61.4 p-Channel Semiconductors 81.4.1 Polymers 81.4.2 Small Molecules 261.5 n-Channel Semiconductors 371.5.1 Polymers 371.5.2 Small Molecules 511.6 Ambipolar Semiconductors 681.6.1 Polymers 691.6.2 Small Molecules 771.7 Conclusions 85References 852 Metal-Oxide Thin-Film Transistors for Flexible Electronics 101Yong-Hoon Kimand Sung Kyu Park2.1 Introduction 1012.2 Metal-Oxide TFTs 1022.2.1 Advantages and Applications 1022.2.2 Vacuum Deposition 1022.2.3 Solution Processing 1032.3 Solution-Processed MOThin Films 1032.3.1 Nanoparticle-Based Process 1032.3.2 Sol–Gel-Based Process 1042.3.3 Hybrid Type 1052.4 Low-Temperature-Processed MO TFTs for Flexible Electronics 1052.4.1 Low-Temperature-Processed MO TFTs 1062.4.1.1 Annealing Environment 1062.4.1.2 Ink Formulation 1062.4.1.3 Alternate Annealing Process 1072.4.2 Photochemical Activation of Oxide Semiconductors 1072.5 Summary 114References 1153 Carbon Nanotube Thin-Film Transistors 117Taishi Takenobu3.1 Introduction 1173.2 Individual SWCNTs and SWCNT Thin Films 1183.3 Chemical Vapor Deposition Growth of SWCNT TFTs 1183.4 Solution-Based Methods for SWCNT TFTs 1203.5 Inkjet Printing of Flexible SWCNT TFTs 1203.6 Fabrication Schemes for High-Performance Inkjet-Printed SWCNT TFTs 1223.7 Inkjet Printing of SWCNT CMOS Inverters 1243.8 Inkjet Printing of Aligned SWCNT Films 1283.9 Conclusion 129References 1294 Organic Single-Crystalline Semiconductors for Flexible Electronics Applications 133Marcos A. Reyes-Martinez, Nicholas S. Colella, and Alejandro L. Briseno4.1 Introduction 1334.2 Electronic and Structural Properties of Single Crystals 1344.2.1 Intrinsic Transport Properties 1354.2.2 Crystal Dimensionality 1364.3 Crystallization Techniques 1384.3.1 Growth from Vapor Phase 1384.3.2 Growth from Solution 1384.4 Single-Crystal Flexible Electronic Devices 1394.4.1 Fundamental Mechanics for Flexible Electronics 1394.4.2 Mechanical Versatility of Organic Single Crystals 1414.4.3 Importance of Mechanical Properties Knowledge 1424.4.4 The Elastic Constants of Rubrene Single Crystals 1444.5 Strategies for Flexible Organic Single-Crystal Device Fabrication 1494.5.1 Discrete Ultrathin Single-Crystal Transistor 1504.5.2 Transistor Arrays Based on Micropatterned Single Crystals 1504.5.3 Flexible Single-Crystal Nanowire Devices 1564.6 Conclusions 158Acknowledgments 159References 1595 Solution-Processable Quantum Dots 163Hongbo Li, Vladimir Lesnyak, and Liberato Manna5.1 Introduction 1635.2 Optimization of the Colloidal Synthesis of Quantum Dots by Selection of Suitable Solvents, Ligands, and Precursors 1645.3 Large-Scale Synthesis of Quantum Dots 1665.4 Surface Chemistry of Quantum Dots 1695.5 Post-Synthetic Chemical Modification of Nanocrystals 1745.6 Conclusions and Outlook 179References 1796 Inorganic Semiconductor Nanomaterials for Flexible Electronics 187Houk Jang,Wonho Lee,Min-Soo Kim, and Jong-Hyun Ahn6.1 Introduction 1876.2 Characteristics and Synthesis of Inorganic Semiconducting NMs 1886.2.1 Characteristics of Inorganic NMs 1886.2.1.1 Mechanical Properties of Inorganic NMs in Bending and Stretching 1886.2.1.2 Optoelectrical Properties 1916.2.2 Fabrication of Inorganic NMs for Flexible Electronics 1936.2.2.1 Selective Etching 1936.2.2.2 Anisotropic Etching 1946.2.2.3 Mass Production of Inorganic NMs 1956.2.2.4 Transfer Process 1976.3 Applications in Flexible Electronics 1986.3.1 Flexible Electronics 1986.3.1.1 Flexible Solar Cell 1986.3.1.2 Flexible Memory 2016.3.1.3 Flexible High-Frequency Transistor 2026.3.1.4 Foldable Transistor Using Ultrathin Si NMs 2036.3.2 Conformal Device 2056.3.2.1 Conformal Biomonitoring System 2066.3.3 Stretchable Electronics 2076.3.3.1 Stretchable Logic Circuit 2076.3.3.2 Stretchable Light-Emitting Diode 2116.3.3.3 Photodetector 2116.3.4 Utilizing Deformation of NMs 2156.3.4.1 Nanogenerator and Actuator 2176.3.4.2 RF Device Using Strained NMs 2186.3.5 Transparent Transistor 2196.4 Concluding Remarks 221References 2217 Dielectric Materials for Large-Area and Flexible Electronics 225Sungjun Park, Sujin Sung,Won-June Lee, andMyung-Han Yoon7.1 Introduction 2257.2 General Polymer Dielectrics 2267.3 Cross-Linked Polymer Dielectrics 2277.4 High-k Polymer Dielectrics 2287.5 Electrolyte Gate Dielectrics 2307.6 Self-Assembled Molecular Layer Dielectrics 2347.7 Hybrid Dielectrics 2377.7.1 Organic–Inorganic Laminated Bilayers/Multilayers 2377.7.2 Organic Polymeric/Inorganic Nanoparticle and Nanocomposites 2387.7.3 Hybrid Dielectrics Based on Organosiloxane and Organozirconia 2407.8 Sol–Gel High-k Inorganic Dielectrics 2437.9 Summary and Outlook 246References 2478 Electrolyte-Gating Organic Thin Film Transistors 253Moon Sung Kang, Jeong Ho Cho, and Se Hyun Kim8.1 Introduction 2538.2 Electrolyte-Gated OTFT OperationMechanisms 2558.3 Electrolyte Materials 2578.4 OTFTs Gated with Electrolyte Dielectrics 2608.5 Circuits Based on Electrolyte-Gated OTFTs 2638.6 Conclusions 267References 2679 Vapor Barrier Films for Flexible Electronics 275Seok-Ju Kang, Chuan Liu, and Yong-Young Noh9.1 Introduction 2759.2 Thin-Film Permeation Barrier Layers 2779.3 Permeation through Inorganic Thin Films 2809.4 Time-Resolved Measurements on Barrier Layers 2839.5 Mechanical Limitations of Inorganic Films 2849.6 Mechanics of Films on Flexible Substrates 2849.7 Summary 286References 28710 Latest Advances in Substrates for Flexible Electronics 291William A. MacDonald10.1 Introduction 29110.2 Factors Influencing Film Choice 29210.2.1 Application Area 29210.2.2 Physical Form/Manufacturing Process 29210.3 Film Property Set 29310.3.1 Polymer Type 29310.3.2 Optical Clarity 29510.3.3 Birefringence 29610.3.4 The Effect of Thermal Stress on Dimensional Reproducibility 29610.3.5 Cyclic Oligomers 29810.3.6 Solvent and Moisture Resistance 29910.3.7 The Effect of Mechanical Stress on Dimensional Reproducibility 30210.3.8 Surface Quality 30310.3.8.1 Inherent Surface Smoothness 30310.3.8.2 Surface Cleanliness 30510.4 Summary of Key Properties of Base Substrates 30610.5 Planarizing Coatings 30810.6 Examples of Film in Use 31010.7 Concluding Remarks 312Acknowledgments 312References 312Part II: Devices and Applications 31511 Inkjet Printing Process for Large Area Electronics 317Sungjune Jung, Steve D. Hoath, Graham D. Martin, and Ian M. Hutchings11.1 Introduction 31711.2 Dynamics of Jet Formation 31811.3 Ink Rheology: Non-Newtonian Liquids 32211.4 Dynamics of Drop Impact and Spreading 32711.5 Applications of Inkjet Printing for Large-Area Electronics 33311.5.1 Light-Emitting Diodes 33311.5.2 Thin-Film Transistors 33511.5.3 Solar Cells 33911.6 Summary 340References 34112 Inkjet-Printed Electronic Circuits Based on Organic Semiconductors 345Kang-Jun Baeg and Yong-Young Noh12.1 Printed Organic Electronics 34512.1.1 Printed Electronic Devices 34512.1.2 Inkjet Printing Technology 34712.2 CMOS Technology 34912.2.1 CMOS Inverters 35012.2.2 Ring Oscillators 35312.3 High-Speed Organic CMOS Circuits 35512.3.1 High-Mobility Printable Semiconductors 35612.3.2 Downscaling of Channel Length 35812.3.3 Reducing Contact Resistance 35912.3.4 Reducing Parasitic Overlap Capacitance 35912.4 Conclusions 361References 36213 Large-Area, Printed Organic Circuits for Ambient Electronics 365Tsuyoshi Sekitani, Tomoyuki Yokota, and Takao Someya13.1 Introduction 36513.2 Manufacturing Process and Electrical Characteristics 36613.2.1 Materials and Methods 36613.2.2 Organic Transistors Manufactured Using Printing Technologies 36613.2.2.1 Manufacturing Process for DNTT Transistors 36913.2.2.2 Electrical Performance of DNTT Transistors 36913.2.2.3 Manufacturing Process for All-Printed Transistors 36913.2.2.4 Electrical Performance of All-Printed Transistors 36913.2.3 Mechanical Characteristics 37013.2.4 Inverter Circuits and Ring Oscillator Using Printed Transistors 37113.2.5 Printed Organic Floating-Gate Transistors 37113.2.5.1 Manufacturing Process 37313.2.5.2 Electrical Performance 37313.3 Demonstration 37613.3.1 Organic Active-Matrix LED Pixel Circuits 37613.3.2 Large-Area Flexible Pressure Sensor Sheet 37613.3.3 Intelligent Sensor Catheter for Medical Diagnosis 37813.4 Future Prospects 378Acknowledgments 378References 37914 Polymer and Organic Nonvolatile Memory Devices 381Seung-Hoon Lee, Yong Xu, and Yong-Young Noh14.1 Introduction 38114.2 Resistive Switching Memories 38414.2.1 Fundamentals of Resistive Switching Principles 38414.2.2 Mechanisms of Resistive Switching 38614.2.2.1 Filamentary Conduction 38614.2.2.2 Space Charge and Traps 38714.2.2.3 Charge Transfer 38814.2.2.4 Ionic Conduction 38814.2.3 The Role of π-Conjugated Material in Switching Process 38814.2.4 Recent Flexible RRAM Based on Organic–Inorganic Bistable Materials 38914.3 Charge Storage in Transistor Gate Dielectric 39014.3.1 Operation of Charge-Storage OFET Memory Devices 39114.3.2 Charge Storage in Polymer Electrets 39214.3.3 Nanoparticle-Embedded Gate Dielectrics 39414.4 Polymer Ferroelectric Devices 39614.4.1 Materials 39914.4.2 Principles of Memory Operation 40114.4.2.1 Capacitor 40214.4.2.2 Field-Effect Transistor 40214.5 Conclusions 407References 40715 Flexible Displays 411Chung-kun Song and Gi-Seong Ryu15.1 Introduction 41115.2 Flexible Substrates 41215.2.1 Thermal Stability 41315.2.2 Optical Transparency 41415.2.3 Permeation of Oxygen and Moisture 41415.2.4 Chemical Resistance 41515.2.5 Surface Roughness 41515.3 Display Mode 41515.4 Thin-Film Transistor 41815.4.1 a-Si TFT 41915.4.2 LTPS TFT 42015.4.3 Oxide TFT 42015.4.4 OTFT 42215.5 AMOLED Panel with Printing Technology 42615.5.1 Design and Fabrication of OTFT Backplane 42615.5.2 Screen Printing of the Gate Electrodes and Scan Bus Lines 42815.5.3 Inkjet Printing of TIPS-Pentacene for OTFTs 43115.6 Fabrication of the OLED and AMOLED Panel 43315.7 Future Prospects 435References 43516 Flexible Organic Solar Cells for Scalable, Low-Cost Photovoltaic Energy Conversion 439Seunghyup Yoo, Jongjin Lee, Donggeon Han, and Hoyeon Kim16.1 Overview of Organic Photovoltaic (OPV) Cells 43916.1.1 Motivation for OPV Cells 43916.1.2 Fundamentals of OPV Technologies 44116.1.2.1 General Operation of PV Cells 44116.1.2.2 Working Principle of OPV Cells 44216.1.2.3 Major Components and Various Configuration of OPV Cells 44416.2 Efforts toward Realization of Flexible OSCs 44916.2.1 Overview 44916.2.2 Transparent Electrodes (TEs) for Flexible OSCs 44916.2.2.1 Metal Grids Combined with Other Transparent Electrodes 45016.2.2.2 Other Flexible Transparent Electrodes 45116.2.3 Encapsulation Issues 45416.3 Flexible OSCs for High-Throughput Production: A Printing-Based Approach to Low-Cost Solar Energy Conversion 45516.3.1 Printing Technology Overview 45516.3.2 Review of Printing Technologies Used for OSCs 45616.3.2.1 Screen Printing 45616.3.2.2 Droplet Coating and Printing 45616.3.2.3 Blade/Knife Edge Coating and Slot-Die Printing 45816.3.2.4 Gravure Printing 46016.3.2.5 Other Coating/Printing Methods 46016.3.3 Issues in Module Fabrication 46216.4 Summary and Outlook 463References 46317 Flexible Inorganic Photovoltaics 469Zhuoying Chen17.1 Introduction 46917.2 Thin Crystalline Solar Cells Transferred onto Flexible Substrates 47017.3 Thin-Film Solar Cells Grown Directly onto Flexible Substrates by Vapor Deposition 47217.4 Solution-ProcessedThin-Film Solar Cells Deposited Directly onto Flexible Substrates 47717.5 Summary 480References 48018 Scalable and Flexible Bioelectronics and Its Applications to Medicine 485Salvatore Iannotta, Pasquale D’Angelo, Agostino Romeo, and Giuseppe Tarabella18.1 Biosensing and Bioelectronics: A Fast Growing Field and a Challenging Research Area 48518.2 Inorganic and Silicon-Based Flexible Electronics for Biosensing Devices 49018.2.1 Inorganic Semiconductors for Flexible Electronics: From Hybrids and Inorganic Semiconducting Composites to Silicon 49118.2.2 Bioapplications: From Cell–Silicon Junctions Toward Neuroprosthesis and Neuromedicine 49618.3 EGOFETs for Flexible Biosensing 50718.3.1 EGOFET: Architecture,Working Principle, and Materials 50818.3.2 Biochemical Sensing 51218.3.3 Interfacing with Neural Tissue 51718.3.4 Opportunities and Challenges 51918.4 OECTs for Biosensing and Biomonitoring 52018.4.1 OECT Architecture andWorking Principle 52018.4.2 The Applications of OECT as a Biological Sensor 52218.4.2.1 Drug Nanocarriers for Drug Delivery 52218.4.2.2 Dopamine and Eumelanin Sensing 52318.4.2.3 Sensing Cell and Bacterial Activity 52618.4.2.4 DNA 52818.4.2.5 Biosensing Toward e-Textile Applications 52918.4.3 Organic Electronic Ion Pumps (OEIPs) 52918.5 Conclusions and Outlook 531References 533Index 541