Wong / Salleo Flexible Electronics

Materials and Applications
1. Auflage 2009
ISBN: 978-0-387-74363-9
Verlag: Springer
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, Band 11, 462 Seiten

Reihe: Electronic Materials: Science & Technology

This excellent volume covers a range of materials used for flexible electronics, including semiconductors, dielectrics, and metals. The functional integration of these different materials is treated as well. Fundamental issues for both organic and inorganic materials systems are included. A corresponding overview of technological applications, based on each materials system, is presented to give both the non-specialist and the researcher in the field relevant information on the status of the flexible electronics area.

William Wong received his B.S. from the University of California, Los Angeles, in 1990, his M.S. from the University of California, San Diego, in 1995 and his Ph.D. from the University of California, Berkeley, in 1999.  He was an associated research engineer for Siemens Solar Industries in Camarillo, CA, form 1990-1992. Since 2000, he has been a senior member of the research staff at the Palo Alto Research Center. Alberto Salleo received his physics degree in 1994 from Ecole Polytechnique in France; his M.S. from the University of California, Berkeley in 1998; and his Ph.D. from the University of California, Berkeley, in 2001.  He has held several positions such as visiting scholar and graduate student researcher and currently is a researcher in the Electronic  Materials Laboratory at the Palo Alto Research Center. In January, 2006, he will become an Assistant Professor for the Department of Materials Science and Engineering at Stanford University.

Autoren/Hrsg.

Salleo, Alberto

Wong, William S.

Inhaltsverzeichnis

1;Flexible Electronics: Materials and Applications;2
2;Preface;6
3;Contents;9
4;Contributors;16
5;to 1 Overview of Flexible Electronics Technology;18
5.1;1.1 History of Flexible Electronics;18
5.2;1.2 Materials for Flexible Electronics;19
5.2.1;1.2.1 Degrees of Flexibility;20
5.2.2;1.2.2 Substrates;22
5.2.2.1;1.2.2.1 Thin Glass;23
5.2.2.2;1.2.2.2 Plastic Film;24
5.2.2.3;1.2.2.3 Metal Foil;24
5.2.3;1.2.3 Backplane Electronics;25
5.2.3.1;1.2.3.1 Silicon Thin-Film Transistors;26
5.2.3.2;1.2.3.2 Organic Thin-Film Transistors;27
5.2.3.3;1.2.3.3 Transparent Thin-Film Transistors;27
5.2.3.4;1.2.3.4 Materials for Interconnects and Contacts;28
5.2.4;1.2.4 Frontplane Technologies;29
5.2.4.1;1.2.4.1 Liquid Crystal Displays;29
5.2.4.2;1.2.4.2 Electrophoretic Displays;30
5.2.4.3;1.2.4.3 Organic Light-Emitting Displays;31
5.2.4.4;1.2.4.4 Sensors;32
5.2.4.5;1.2.4.5 Actuators;33
5.2.4.6;1.2.4.6 Electronic Textiles;33
5.2.5;1.2.5 Encapsulation;33
5.3;1.3 Fabrication Technology for Flexible Electronics;35
5.3.1;1.3.1 Fabrication on Sheets by Batch Processing;35
5.3.2;1.3.2 Fabrication on Web by Roll-to-Roll Processing;36
5.3.3;1.3.3 Additive Printing;37
5.4;1.4 Outlook;37
6;to 2 Mechanical Theory of the Film-on-Substrate-Foil Structure: Curvature and Overlay Alignment in Amorphous Silicon Thin-Film Devices Fabricated on Free-Standing Foil Substrates;46
6.1;2.1 Introduction;46
6.2;2.2 Theory;49
6.2.1;2.2.1 The Built-in Strain 0 bi ;52
6.3;2.3 Applications;53
6.3.1;2.3.1 Strain in the Substrate, 0 s (T d ), and the Film, 0 f (T d ), at the Deposition Temperature T d ;53
6.3.2;2.3.2 Strain in the Substrate, 0 s (T r ), and the Film, 0 f (T r ), at Room Temperature T r ;55
6.3.3;2.3.3 Radius of Curvature R of the Workpiece;59
6.3.4;2.3.4 Strain of the Substrate and the Curvature of the Workpiece for a Three-Layer Structure;63
6.3.5;2.3.5 Experimental Results for a-Si:H TFTs Fabricated on Kapton;64
6.4;2.4 Conclusions;67
7;to 3 Low-temperature Amorphous and Nanocrystalline Silicon Materials and Thin-film Transistors;69
7.1;3.1 Introduction;69
7.2;3.2 Low-temperature Amorphous and Nanocrystalline Silicon Materials;71
7.2.1;3.2.1 Fundamental Issues for Low-temperature Processing;71
7.2.2;3.2.2 Low-temperature Amorphous Silicon;72
7.2.3;3.2.3 Low-temperature Nanocrystalline Silicon;72
7.3;3.3 Low-temperature Dielectrics;73
7.3.1;3.3.1 Characteristics of Low-temperature Dielectric Thin-film Deposition;73
7.3.2;3.3.2 Low-temperature Silicon Nitride Characteristics;73
7.3.3;3.3.3 Low-temperature Silicon Oxide Characteristics;74
7.4;3.4 Low-temperature Thin-film Transistor Devices;75
7.4.1;3.4.1 Device Structures and Materials Processing;76
7.4.2;3.4.2 Low-Temperature a-Si:H Thin-Film Transistor Device Performance;77
7.4.3;3.4.3 Contacts to a-Si:H Thin-film Transistors;78
7.4.4;3.4.4 Low-temperature Doped nc-Si Contacts;80
7.4.5;3.4.5 Low-temperature nc-Si TFTs;82
7.5;3.5 Device Stability;83
7.6;3.6 Conclusions and Future Prospective;85
8;to 4 Amorphous Silicon: Flexible Backplane and Display Application;90
8.1;4.1 Introduction;90
8.2;4.2 Enabling Technologies for Flexible Backplanes and Displays;91
8.2.1;4.2.1 Flexible Substrate Technologies;91
8.2.1.1;4.2.1.1 Flexible Stainless Steel Substrates;91
8.2.1.2;4.2.1.2 Flexible Plastic Substrates;92
8.2.1.3;4.2.1.3 Flexible PEN Plastic Substrates;94
8.2.2;4.2.2 TFT Technologies for Flexible Backplanes;97
8.2.2.1;4.2.2.1 Low-temperature a-Si TFT;102
8.2.3;4.2.3 Display Media for Flexible Displays (LCD, Reflective-EP, OLED);104
8.2.3.1;4.2.3.1 LCD Media;104
8.2.3.2;4.2.3.2 Electrophoretic Display Media;104
8.2.3.3;4.2.3.3 OLED Display Media;105
8.2.4;4.2.4 Barrier Layers;105
8.3;4.3 Flexible Active Matrix Backplane Requirements for OLED Displays;106
8.3.1;4.3.1 Active Matrix Addressing;107
8.3.1.1;4.3.1.1 Voltage Programming;107
8.3.1.2;4.3.1.2 Current Programming;109
8.4;4.4 Flexible AMOLED Displays Using a-Si TFT Backplanes;110
8.4.1;4.4.1 Backplane Fabrication Using PEN Plastic Substrates;110
8.4.2;4.4.2 Flexible OLED Display Fabrication;113
8.4.3;4.4.3 Flexible AMOLED Display Fabrication with Thin-film Encapsulation;115
8.5;4.5 Flexible Electrophoretic Displays Fabricated using a-Si TFT Backplanes;117
8.6;4.6 Outlook for Low-Temperature a-Si TFT for Flexible Electronics Manufacturing;117
9;to 5 Flexible Transition Metal Oxide Electronics and Imprint Lithography;122
9.1;5.1 Introduction;122
9.2;5.2 Previous Work;123
9.3;5.3 Properties of Transistor Materials;128
9.3.1;5.3.1 Semiconductors;128
9.3.2;5.3.2 Dielectrics;130
9.3.3;5.3.3 Contact Materials;131
9.4;5.4 Device Structures;131
9.5;5.5 Fabrication on Flexible Substrates;134
9.5.1;5.5.1 Imprint Lithography;135
9.5.2;5.5.2 Self-Aligned Imprint Lithography;137
9.5.3;5.5.3 SAIL Transistor Results;141
9.5.4;5.5.4 Summary of Imprint Lithography;142
9.6;5.6 Flexible TMO Device Results;142
9.7;5.7 Future Problems and Areas of Research;147
9.7.1;5.7.1 Carrier Density Control;149
9.7.2;5.7.2 Low-Temperature Dielectrics;150
9.7.3;5.7.3 Etching of TMO Materials;150
9.7.4;5.7.4 P-type TMO;151
9.7.5;5.7.5 Stability;151
9.7.6;5.7.6 Flexure and Adhesion of TMO;152
9.7.7;5.7.7 Flexible Fabrication Method Yields;152
9.8;5.8 Summary;153
10;to 6 Materials and Novel Patterning Methods for Flexible Electronics;158
10.1;6.1 Introduction;158
10.2;6.2 Materials Considerations for Flexible Electronics;159
10.2.1;6.2.1 Overview;160
10.2.2;6.2.2 Inorganic Semiconductors and Dielectrics;160
10.2.3;6.2.3 Organic Semiconductors and Dielectrics;161
10.2.4;6.2.4 Conductors;164
10.3;6.3 Print-Processing Options for Device Fabrication;165
10.3.1;6.3.1 Overview;165
10.3.2;6.3.2 Control of Feature Sizes of Jet-Printed Liquids;166
10.3.3;6.3.3 Jet-Printing for Etch-Mask Patterning;168
10.3.4;6.3.4 Methods for Minimizing Feature Size;169
10.3.5;6.3.5 Printing Active Materials;171
10.4;6.4 Performance and Characterization of Electronic Devices;172
10.4.1;6.4.1 Overview;172
10.4.2;6.4.2 Bias Stress in Organic Thin-Film Transistors;173
10.4.2.1;6.4.2.1 Continuous Biasing;173
10.4.2.2;6.4.2.2 Pulsed Biasing;175
10.4.2.3;6.4.2.3 Long-Term Stress Effects;177
10.4.3;6.4.3 Nonideal Scaling of Short-Channel Organic TFTs;178
10.4.4;6.4.4 Low-Temperature a-Si:H TFT Device Stability;180
10.4.5;6.4.5 Low-temperature a-Si:H p--i--n Devices;182
10.5;6.5 Printed Flexible Electronics;185
10.5.1;6.5.1 Overview;185
10.5.2;6.5.2 Digital Lithography for Flexible Image Sensor Arrays;185
10.5.3;6.5.3 Printed Organic Backplanes;187
10.5.3.1;6.5.3.1 Hybrid Fabrication;187
10.5.3.2;6.5.3.2 All-Printed Electronics;189
10.6;6.6 Conclusions and Future Prospects;190
11;to 7 Sheet-Type Sensors and Actuators;197
11.1;7.1 Introduction;197
11.2;7.2 Sheet-type Image Scanners;198
11.2.1;7.2.1 Imaging Methods;199
11.2.2;7.2.2 Device Structure and Manufacturing Process;200
11.2.3;7.2.3 Electronic Performance of Organic Photodiodes;204
11.2.4;7.2.4 Organic Transistors;205
11.2.5;7.2.5 Photosensor Cells;207
11.2.6;7.2.6 Issues Related to Device Processes: Pixel Stability and Resolution;209
11.2.7;7.2.7 A Hierarchal Approach for Slow Organic Circuits;210
11.2.8;7.2.8 The Double-Wordline and Double-Bitline Structure;210
11.2.9;7.2.9 A New Dynamic Second-Wordline Decoder;213
11.2.10;7.2.10 Higher Speed Operation with Lower Power Consumption;213
11.2.11;7.2.11 New Applications and Future Prospects;214
11.3;7.3 Sheet-Type Braille Displays;215
11.3.1;7.3.1 Manufacturing Process;215
11.3.2;7.3.2 Electronic Performance of Braille Cells;218
11.3.3;7.3.3 Organic Transistor-based SRAM;224
11.3.4;7.3.4 Reading Tests;225
11.3.5;7.3.5 Future Prospects;226
11.4;7.4 Summary;226
12;to 8 Organic and Polymeric TFTs for Flexible Displays and Circuits;229
12.1;8.1 Introduction;229
12.2;8.2 Important Organic TFT Parameters for Electronic Systems;230
12.2.1;8.2.1 Field-Effect Mobility;230
12.2.2;8.2.2 Threshold Voltage;233
12.2.3;8.2.3 Subthreshold Swing;234
12.2.4;8.2.4 Leakage Currents;236
12.2.5;8.2.5 Contact Resistance;236
12.2.6;8.2.6 Capacitances and Frequency Response;237
12.2.7;8.2.7 TFT Nonuniformity;239
12.2.8;8.2.8 Bias-Stress Instability and Hysteresis;239
12.3;8.3 Active Matrix Displays;241
12.3.1;8.3.1 Introduction;241
12.3.2;8.3.2 Liquid Crystal and Electrophoretic Displays;242
12.3.2.1;8.3.2.1 Introduction;242
12.3.2.2;8.3.2.2 Electro-Optic Response of Liquid Crystal Materials;245
12.3.2.3;8.3.2.3 Electro-Optic Response of Electrophoretic Materials;247
12.3.2.4;8.3.2.4 Liquid Crystal and Electrophoretic Display Architecture;248
12.4;8.4 Active Matrix OLED Displays;250
12.4.1;8.4.1 Introduction;250
12.4.1.1;8.4.1.1 Electro-Optic Response of Organic Light-Emitting Diodes;251
12.4.1.2;8.4.1.2 OLED Display Architectures;252
12.4.1.3;8.4.1.3 Nonideal Behavior in AMOLED Pixels;255
12.5;8.5 Using Organic TFTs for Electronic Circuits;256
12.5.1;8.5.1 Thin-Film Transistor Circuits;256
12.5.1.1;8.5.1.1 Comparison with Silicon CMOS;256
12.5.1.2;8.5.1.2 Digital OTFT Design;258
12.5.2;8.5.2 Frequency Limitations of OTFTs;260
12.5.3;8.5.3 Integrated Display Drivers;261
12.5.4;8.5.4 Radio Frequency Identification Tags;262
12.5.4.1;8.5.4.1 Introduction;262
12.5.4.2;8.5.4.2 Using OTFT Technology for RFID Tags;264
12.6;8.6 Conclusion;270
13;to 9 Semiconducting Polythiophenes for Field-Effect Transistor Devices in Flexible Electronics: Synthesis and Structure Property Relationships;275
13.1;9.1 Introduction;275
13.2;9.2 Polymerization of Thiophene Monomers;277
13.2.1;9.2.1 General Considerations;278
13.2.2;9.2.2 Synthetic Routes for the Preparation of Thiophene Polymers;278
13.2.2.1;9.2.2.1 Chemical Oxidation Routes;279
13.2.2.2;9.2.2.2 Electrochemical Oxidation Routes;281
13.2.2.3;9.2.2.3 Transition Metal Catalyzed Cross-coupling Methodologies;281
13.2.2.4;9.2.2.4 Dehalogenative Polymerization;287
13.3;9.3 Poly(3-Alkylthiophenes);287
13.3.1;9.3.1 Electrical Properties;289
13.3.2;9.3.2 Thin-film Device Processing and Morphology;290
13.3.3;9.3.3 Doping and Oxidative Stability;291
13.4;9.4 Polythiophene Structural Analogues;293
13.5;9.5 Thienothiophene Polymers;300
13.5.1;9.5.1 Poly(Thieno(2,3-b)Thiophenes);300
13.5.2;9.5.2 Poly(Thieno(3,2-b)Thiophenes);302
13.6;9.6 Summary;306
14;to 10 Solution Cast Films of Carbon Nanotubes for Transparent Conductors and Thin Film Transistors;311
14.1;10.1 Introduction: Nanoscale Carbon for Electronics, the Value Proposition;311
14.2;10.2 Carbon NT Film Properties;312
14.2.1;10.2.1 Carbon Nanotubes: The Building Blocks;312
14.2.2;10.2.2 Carbon Nanotube Network as an Electronic Material;312
14.2.3;10.2.3 Electrical and Optical Properties of NT Films;314
14.2.3.1;10.2.3.1 Concentration Dependent Conductivity;315
14.2.3.2;10.2.3.2 Temperature Dependent Conductivity;316
14.2.3.3;10.2.3.3 Frequency Dependence and Optical Conductivity;316
14.2.3.4;10.2.3.4 Geometric Factors;317
14.2.4;10.2.4 Doping and Chemical Functionalization;318
14.3;10.3 Fabrication Technologies;319
14.3.1;10.3.1 Solubilization;320
14.3.2;10.3.2 Deposition;320
14.3.2.1;10.3.2.1 Spraying;321
14.3.2.2;10.3.2.2 Slot Coating;322
14.3.2.3;10.3.2.3 Spin Coating;322
14.3.2.4;10.3.2.4 Filtration/Stamping;322
14.4;10.4 Carbon NT Films as Conducting and Optically Transparent Material;323
14.4.1;10.4.1 Network Properties: Sheet Conductance and Optical Transparency;323
14.4.2;10.4.2 Applications: ITO Replacement;326
14.4.3;10.4.3 Challenges and the Path Forward;326
14.5;10.5 TFTs with Carbon Nanotube Conducting Channels;327
14.5.1;10.5.1 Device Characteristics;328
14.5.2;10.5.2 Device Parameters;330
14.5.2.1;10.5.2.1 Mobility;331
14.5.2.2;10.5.2.2 ON/OFF Ratio;332
14.5.2.3;10.5.2.3 Device Capacitance;333
14.5.2.4;10.5.2.4 Operating Voltage;334
14.5.2.5;10.5.2.5 Threshold Voltage;335
14.5.2.6;10.5.2.6 Subthreshold Swing;335
14.5.2.7;10.5.2.7 Hysteresis;335
14.5.2.8;10.5.2.8 Device Stability;336
14.5.2.9;10.5.2.9 Doping and Logic Elements;337
14.5.3;10.5.3 Challenges and the Path Forward;337
14.6;10.6 Conclusions;338
15;to 11 Physics and Materials Issues of Organic Photovoltaics;343
15.1;11.1 Introduction;343
15.2;11.2 Basic Operation;343
15.2.1;11.2.1 Photocurrent;345
15.2.2;11.2.2 Dark Current;345
15.3;11.3 Organic and Hybrid Solar Cell Architectures;346
15.4;11.4 Materials;347
15.5;11.5 Light Absorption;348
15.6;11.6 Exciton Harvesting;352
15.6.1;11.6.1 Effects of Disorder;354
15.6.2;11.6.2 Extrinsic Defects;358
15.6.3;11.6.3 Measuring Exciton Harvesting;358
15.6.4;11.6.4 Approaches to Overcome Small Diffusion Lengths;361
15.7;11.7 Exciton Dissociation;363
15.8;11.8 Dissociating Geminate Pairs;364
15.9;11.9 Heterojunction Energy Offsets;369
15.10;11.10 Charge Transport and Recombination;371
15.10.1;11.10.1 Diffusion-Limited Recombination;373
15.10.2;11.10.2 Interface-Limited (Back Transfer Limited) Recombination;374
15.10.3;11.10.3 Measurements Relevant for Extracting Charge;377
15.11;11.11 Nanostructures;378
15.12;11.12 Efficiency Limits and Outlook;381
16;to 12 Bulk Heterojunction Solar Cells for Large-Area PV Fabrication on Flexible Substrates;386
16.1;12.1 Introduction and Motivation;386
16.1.1;12.1.1 Photovoltaics;386
16.1.2;12.1.2 Technology Overview;387
16.1.3;12.1.3 Motivation for Large-Area, Solution-Processable Photovoltaics;388
16.2;12.2 The Concept of Bulk Heterojunction Solar Cells;389
16.2.1;12.2.1 Basics of Organic Solar Cell Materials;390
16.2.2;12.2.2 Fundamentals of Photovoltaics;391
16.2.2.1;12.2.2.1 Solar Radiation;391
16.2.2.2;12.2.2.2 Band Considerations of a Two-Level System;392
16.2.2.3;12.2.2.3 Transport Phenomena;394
16.2.2.4;12.2.2.4 Current--Voltage Characteristic;396
16.2.2.5;12.2.2.5 The V oc ;397
16.2.3;12.2.3 Understanding and Optimization of BHJ Composites;398
16.2.3.1;12.2.3.1 The One-Diode Model for Organic Solar Cell;399
16.2.3.2;12.2.3.2 Consequences of the One-Diode Model;405
16.2.3.3;12.2.3.3 Application to Large-Area Solution-Processed Solar Cells;409
16.3;12.3 Challenges for Large-Area Processing;414
16.3.1;12.3.1 Production Scheme;414
16.3.2;12.3.2 Encapsulation of Flexible Solar Cells;417
16.4;12.4 Conclusions;421
17;to 13 Substrates and Thin-Film Barrier Technology for Flexible Electronics;426
17.1;13.1 Introduction;426
17.2;13.2 Barrier Requirements;427
17.2.1;13.2.1 Generic Requirements;429
17.2.1.1;13.2.1.1 Barrier Level;429
17.2.1.2;13.2.1.2 Optical Properties;429
17.2.1.3;13.2.1.3 Mechanical Flexibility;429
17.2.1.4;13.2.1.4 Compatibility of the Barrier Coating;430
17.2.2;13.2.2 Substrate-Specific Requirements;430
17.2.2.1;13.2.2.1 Substrate Options;430
17.2.2.2;13.2.2.2 Chemical Resistance;431
17.2.2.3;13.2.2.3 High-Temperature Stability;432
17.2.2.4;13.2.2.4 Surface Quality;432
17.3;13.3 Thin-Film Barrier Technology;432
17.3.1;13.3.1 Historical Background;432
17.3.2;13.3.2 Permeation Measurement Techniques;433
17.3.3;13.3.3 Permeation Through Thin-Film Barriers;439
17.3.3.1;13.3.3.1 Simple Single Layer Barrier Films;439
17.3.3.2;13.3.3.2 Advanced Barrier Films;442
17.4;13.4 BarrierDevice Integration;449
17.4.1;13.4.1 Substrate and Barrier Compatibility with OLEDs;450
17.4.2;13.4.2 Thin-Film Encapsulation;453
17.5;13.5 Concluding Remarks;455
18;Index;463