Printed Electronics

Prof Zheng Cui, Chinese Academy of Sciences, ChinaZheng Cui obtained a PhD in electronic engineering in 1988 and became a Visiting Fellow at the Microelectronics Research Center, Cambridge University, UK, in 1989. Cui joined the Rutherford Appleton Laboratory, UK, in 1993 and subsequently became a Principal Scientist and group leader there in 1999. In October 2009, after working in the UK for 20 years, Cui returned to China and founded the Printable Electronics Research Center at the Suzhou Institute of Nanotech, which was the first research center dedicated to printed electronics R&D in China.CONTRIBUTORSDr Song Qiu, Chinese Academy of Sciences, ChinaSong Qiu received a B.S. Polymer Materials and Engineering in 2000, followed by a PhD in Polymer Chemistry and Physics?from Jilin University in 2005.Dr Jian Lin, Chinese Academy of Sciences, ChinaJian Lin received his PhD degree in Polymer Chemistry and Physics from Changchun Institute of Applied Chemistry, Chinese Academy of Sciences in 2008.Dr. Jianwen Zhao, Chinese Academy of Sciences, ChinaJianwen Zhao received his PhD degree in Technical Institute of Physics and Chemistry, Chinese Academic of Science, in 2008.Dr. Chang-Qi Ma, Chinese Academy of Sciences, ChinaChang-Qi Ma received his bachelor's degree in Chemistry from Beijing Normal University in 1998. In 2003 he obtained his PhD degree at the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences in Beijing with Professor B.-W. Zhang.Dr. Zheng Chen, Chinese Academy of Sciences, ChinaZheng Chen received the B.S. degree in materials physics and PhD degree in condensed matter physics from the University of Science and Technology of China, in 2002 and 2007, respectively.Dr. Wenming Su, Chinese Academy of Sciences, ChinaWenming Su is anAssociate professor of Printable Electronics Research Center, Suzhou Institute of Nanotech, Chinese Academy of Sciences.

• Preface xii1 Introduction 1Zheng Cui1.1 What is Printed Electronics? 11.2 The Importance of Developing Printed Electronics 111.3 Multidisciplinary Nature of Printed Electronics 151.4 Structure and Content of the Book 17References 192 Organic Printable Electronic Materials 21Song Qiu and Chunshan Zhou2.1 Introduction 212.2 Organic Conductive Materials 222.2.1 Characteristics of Organic Conductive Materials 222.2.2 History of Organic Conductive Materials 232.2.3 Conductive Polymer 232.2.3.1 Structural Conductive Polymer 232.2.3.2 Composite Conductive Polymer 252.2.4 PEDOT 252.3 Printable Organic Small Molecular Semiconductors 272.3.1 Fused Aromatic Compounds 282.3.2 Heterocyclic Sulfur Compounds and Oligothiophenes 302.3.3 Other Materials with High Mobility 332.4 Printable Polymeric Semiconductor 342.4.1 P‐type Polymer Semiconductors 352.4.1.1 Sulfur‐containing Heterocyclic Polymeric Semiconductors 352.4.1.2 Phenyl‐containing Polymeric Semiconductors 372.4.1.3 Other p‐type Polymeric Semiconductors 392.4.2 N‐type Polymer Semiconductors 392.4.3 Ambipolar Transistor and Related Polymer Materials 412.4.4 Outlook 432.5 Other Printable Organic Electronic Materials 442.5.1 Organic Insulating Materials 442.5.2 Organic Materials for Sensors 472.6 Summary 49References 493 Inorganic Printable Electronic Materials 54Zheng Chen3.1 Introduction 543.2 Metallic Materials 563.2.1 Metallic Ink 563.2.2 Post‐printing Process 633.2.3 Metal Nanowire 643.3 Transparent Oxide 663.3.1 Transparent Oxide Semiconductor and Conductor 663.3.2 Low Temperature Solution Processing 683.3.3 Doped Transparent Oxide Nanoparticles 713.4 Single‐wall Carbon Nanotube 723.4.1 Preparation and Selective Chemistry of SWNT 723.4.2 Purification of SWNT 763.4.3 Metallic SWNT Thin Film 773.4.4 Semiconducting SWNT Thin Film 793.5 Graphene 833.6 Silicon and Germanium 863.7 Metal Chalcogenides Semiconductor and Quantum Dots 903.7.1 Metal Chalcogenides Semiconductor 903.7.2 Quantum Dots 903.8 Nanoparticle/Polymer Dielectric Composites 923.9 Summary 95References 964 Printing Processes and Equipments 106Jian Lin4.1 Introduction 1064.2 Jet Printing 1084.2.1 Inkjet Printing 1084.2.1.1 Working Principles 1084.2.1.2 Pattern Preparation 1084.2.1.3 Application in Printed Electronics 1104.2.2 Aerosol Jet Printing 1114.2.2.1 Working Principle 1124.2.2.2 Pattern Preparation 1124.2.2.3 Advantages and Challenges 1134.2.3 Electrohydrodynamic Jet Printing 1144.2.4 Advantages and Disadvantages 1144.3 Direct Replicate Printing 1154.3.1 Screen Printing 1164.3.1.1 Working Principle 1164.3.1.2 Screen Mask 1174.3.1.3 Advantages and Disadvantages 1184.3.1.4 Applications 1184.3.2 Gravure Printing 1184.3.2.1 Principle and System 1184.3.2.2 Gravure Plate 1204.3.2.3 Advantages and Disadvantages 1204.3.2.4 Applications in Printed Electronics 1214.3.3 Flexographic Printing 1224.3.3.1 Principle and System 1224.3.3.2 Printing Plate 1234.3.3.3 Advantages and Disadvantages 1234.3.3.4 Applications in Printed Electronics 1254.4 Indirect Replicate Printing 1254.4.1 Offset Printing 1254.4.2 Gravure Offset Printing 1264.4.3 Pad Printing 1284.5 Pre‐printing Processes 1294.5.1 Pattern Design 1294.5.2 Modification of Surface Energy 1304.5.3 Surface Coating 1314.5.4 Embossing and Nanoimprinting 1314.6 Post‐printing Processes 1344.6.1 Sintering 1344.6.2 UV Curing 1354.6.3 Annealing 1354.7 Summary 136References 1375 Printed Thin Film Transistors 145Jianwen Zhao5.1 Introduction 1455.2 Types of Transistors 1465.3 Working Principles of Transistors 1475.3.1 Basic Mechanism of MOSFETs 1475.3.2 Charge Carriers and Carrier Mobility 1495.3.3 Basic Parameters of TFT 1495.3.3.1 Effective Mobility 1495.3.3.2 Operating Voltage 1515.3.3.3 Device Capacitance 1515.3.3.4 Threshold Voltage (Vt) 1535.3.3.5 Subthreshold Swing (SS) 1555.3.3.6 On/off Current Ratio (Ion /Ioff) 1555.3.3.7 Hysteresis 1565.3.3.8 Transconductance (gm) 1575.3.3.9 Stability 1575.4 Structures and Fabrication of TFTs 1575.4.1 Structures of TFTs 1575.4.2 Characteristics of TFTs 1595.4.3 Fabrication of TFTs 1605.4.3.1 Fabrication of Electrodes 1605.4.3.2 Fabrication of Active Layer 1635.4.3.3 Fabrication of Dielectric Layers 1675.5 Fully Printed TFTs 1725.5.1 Printability of Electronic Materials 1725.5.2 Influence of Surface Morphology 1735.5.3 Interface Effect of Printed TFTs 1735.5.3.1 Effect of Semiconductor/Dielectric Interface 1755.5.3.2 Effect of Semiconductor/Semiconductor Interface 1765.5.3.3 Effect of Semiconductor/Electrode Interface 1775.5.4 Effect of Channel Length 1785.5.5 Summary of Issues in Printing TFTs 1795.5.5.1 Printable Inks and Printing Processes 1795.5.5.2 Printed Electrodes 1805.5.5.3 Printed Dielectric Thin Films 1805.6 Advances in Printed TFTs 1805.6.1 Printed Inorganic TFTs 1815.6.1.1 SWCNT TFTs 1815.6.1.2 Metal Oxide TFTs 1825.6.1.3 Metal Dichalcogenide and Graphene TFTs 1845.6.2 Printed Organic TFTs 1875.7 Basics of Printed Logic Circuits 1895.7.1 NAND and NOR Gates 1905.7.2 Inverter 1905.7.3 Ring Oscillator 1905.7.4 Flip‐flop 1935.7.5 Backplane Driving Circuits for Display 1945.8 Summary 196References 1976 Printed Organic Thin Film Solar Cells 201Changqi Ma6.1 Introduction 2016.1.1 Solar Energy and its Utilization 2016.1.2 Classification of Solar Cells 2026.1.3 A Brief History of Organic Thin‐Film Solar Cells 2036.2 Working Principles and Characterization of Organic Solar Cells 2056.2.1 Physical Processes 2056.2.2 Basic Structure 2066.2.3 Characterization 2086.2.3.1 I‐V Characteristics 2086.2.3.2 Spectrum Response 2096.2.4 The Main Factors Influencing Device Performance 2096.2.4.1 Photon Absorption Ability of Organic Semiconductors 2106.2.4.2 Energy Level Arrangement of Donor and Acceptor 2106.2.4.3 Morphology of Photoactive Layer 2126.3 Materials for Organic Solar Cells 2136.3.1 Transparent Substrate 2146.3.2 Transparent Conductive Electrode 2146.3.2.1 Metal Oxide Film 2146.3.2.2 Conductive Polymer Film 2156.3.2.3 Thin Metal Film and Metal Grid 2156.3.2.4 Carbon‐rich Materials 2176.3.3 Organic Semiconductor Materials 2186.3.3.1 p‐Type Organic Semiconductors 2186.3.3.2 n‐Type Organic Semiconductors 2236.3.4 Inorganic Semiconductors 2276.3.5 Other Functional Materials 2296.4 Inverted and Tandem Organic Solar Cells 2296.4.1 Inverted Organic Solar Cells 2296.4.2 Tandem Organic Solar Cells 2316.4.3 Inverted Tandem Organic Solar Cells 2316.5 Fabrication Methods 2326.5.1 Spin Coating 2336.5.2 Doctor Blading 2356.5.3 Screen Printing 2356.5.4 Inkjet Printing 2376.5.5 Other Thin Film Deposition Techniques 2376.6 Roll‐to‐roll Processing 2376.7 Printable Perovskite Solar Cells 2396.8 Summary and Outlook 239References 2407 Printed Organic Light Emission and Display 251Wenming Su7.1 Introduction 2517.1.1 Overview of Lighting and Display 2527.1.2 Overview of Organic Light Emitting Diodes (OLEDs) 2537.2 Mechanism of Organic Light Emission 2547.2.1 Charge Injection and Transport 2557.2.2 Exciton Formation and Light Emission 2567.2.3 Characterization of OLED Performance 2567.2.3.1 Luminous Efficacy 2567.2.3.2 Quantum Efficiency 2577.2.3.3 Color 2577.2.3.4 Three Primary Colors 2587.3 Structures and Materials of OLED 2597.3.1 Small Molecular OLED 2597.3.1.1 Typical Structure 2597.3.1.2 Electrode Materials 2597.3.1.3 Fabrication Process 2607.3.2 Polymer OLEDs 2627.3.3 General OLED Materials 2627.3.3.1 Charge Injection Materials 2637.3.3.2 Charge Transport Materials 2637.3.3.3 Emitter Materials 2647.3.4 Soluble OLED Materials 2657.3.4.1 Printable Polymer OLEDs 2667.3.4.2 Printable Small Molecular OLEDs 2667.3.4.3 Cross‐linking Materials for Printable OLEDs 2677.4 White Lighting OLEDs 2677.4.1 White Light Emission Mechanism 2677.4.2 Important Parameters 2727.4.2.1 CRI 2727.4.2.2 Efficiency and Light Extraction 2737.4.2.3 Lifetime 2757.4.3 Investment in OLED Lighting 2757.5 Fabrication of OLED by Printing 2777.5.1 Spin and Slot Die Coating 2777.5.2 Inkjet Printing 2787.5.3 Screen Printing 2787.5.4 Roll‐to‐roll Printing 2797.5.5 Current Status of the Printed OLED Industry 2807.6 Summary 281References 2828 Encapsulation Technology for Organic Electronic Devices 287Wenming Su8.1 Introduction 2878.2 Aging of Organic Electronic Devices 2888.2.1 Characteristics and Mechanisms of Aging 2888.2.2 Requirements for Organic Electronics Encapsulation 2908.3 Principle of Encapsulation 2918.3.1 Water/oxygen Penetration Mechanism through Thin Films 2918.3.2 Organic/inorganic Multilayer Encapsulation 2928.3.3 Measurement of Encapsulation Property 2938.4 Thin‐film Encapsulation Technology 2968.4.1 History of Thin‐film Encapsulation 2978.4.2 Single Layer Thin‐film Encapsulation 2988.4.3 Multilayer Thin‐film Encapsulation 2988.4.4 BarixTM Thin‐film Encapsulation 3008.4.5 Thin Film Deposition Methods 3018.4.5.1 PECVD 3018.4.5.2 ALD 3038.4.5.3 Parylene Deposition 3038.4.6 Flexibility of Encapsulation Thin Film 3048.4.7 Trends of Thin‐film Encapsulation 3068.5 Applications of Thin‐film Encapsulation 3078.5.1 Encapsulation of Flexible OLED 3078.5.2 Encapsulation of Flexible OPV 3098.6 Summary 313References 3149 Applications and Future Prospects of Printed Electronics 316Zheng Cui9.1 Introduction 3169.2 Application Areas of Printed Electronics 3179.2.1 Organic Photovoltaic 3179.2.2 Flexible Display 3219.2.3 Organic Lighting 3249.2.4 Electronics and Components 3269.2.5 Integrated Smart Systems 3319.3 Challenges for Printed Electronics 3339.3.1 Materials 3339.3.2 Printing Process and Equipment 3359.3.3 Encapsulation 3359.3.4 Design Methodology and Standardization 3369.4 Summary and Outlook 336References 337Index 339