The field of printable organic electronics has emerged as a technology which plays a major role in materials science research and development. Printable organic electronics soon compete with, and for specific applications can even outpace, conventional semiconductor devices in terms of performance, cost, and versatility. Printing techniques allow for large-scale fabrication of organic electronic components and functional devices for use as wearable electronics, health-care sensors, Internet of Things, monitoring of environment pollution and many others, yet-to-be-conceived applications. The first part of Solution-Processable Components for Organic Electronic Devices covers the synthesis of: soluble conjugated polymers; solution-processable nanoparticles of inorganic semiconductors; high-k nanoparticles by means of controlled radical polymerization; advanced blending techniques yielding novel materials with extraordinary properties. The book also discusses photogeneration of charge carriers in nanostructured bulk heterojunctions and charge carrier transport in multicomponent materials such as composites and nanocomposites as well as photovoltaic devices modelling. The second part of the book is devoted to organic electronic devices, such as field effect transistors, light emitting diodes, photovoltaics, photodiodes and electronic memory devices which can be produced by solution-based methods, including printing and roll-to-roll manufacturing.
The book provides in-depth knowledge for experienced researchers and for those entering the field. It comprises 12 chapters focused on:
? novel organic electronics components synthesis and solution-based processing techniques
? advanced analysis of mechanisms governing charge carrier generation and transport in organic semiconductors and devices
? fabrication techniques and characterization methods of organic electronic devices
Providing coverage of the state of the art of organic electronics, Solution-Processable
Components for Organic Electronic Devices is an excellent book for materials scientists, applied physicists, engineering scientists, and those working in the electronics industry.
Table of Contents
Preface xiii
1 Precision and Purity of Conjugated Polymers - To be Ensured Before Processing 1
Thorsten Prechtl and Klaus Mullen
1.1 Polymer Design 1
1.2 Polymer Synthesis 6
1.3 Molecular Structure, Supramolecular Structure, and Interfaces 23
1.4 Beyond Solution Synthesis 30
1.5 Conclusions 33
Acknowledgments 34
References 34
2 Synthesis of Solution-Processable Nanoparticles of Inorganic Semiconductors and Their Application to the Fabrication of Hybrid Materials for Organic Electronics and Photonics 57
Adam Pron, Piotr Bujak, Malgorzata Zagorska, Namchul Cho, Tae-Dong Kim, and Kwang-Sup Lee
2.1 Synthesis and Characterization of Colloidal Semiconductor Nanocrystals 57
2.1.1 Basic Physical Properties of Semiconductor Nanocrystals 57
2.1.2 Introduction to Basic Principles Governing the Synthesis of Nanocrystals 65
2.1.3 Preparation of Binary Nanocrystals 69
2.1.4 Preparation of Ternary and Quaternary Nanocrystals - Effect of Precursor Reactivity on Their Structure, Size, and Shape 78
2.1.5 Core/Shell and Alloyed Nanocrystals - Preparation, Selection of Precursors, and Surfacial Ligand Exchange 92
2.2 Primary Ligand Identifications in Colloidal Nanocrystals of Inorganic Semiconductor - Methodology and Investigation Techniques 112
2.3 Exchange of Primary Ligands for Functional Ones 118
2.3.1 Exchange of Primary Organic Ligands for Inorganic Ones - Transfer of Nanocrystals to Highly Polar Solvents 118
2.3.2 Exchange of Primary Ligands for Organic Ligands of Different Polarity 121
2.3.3 Exchange of Primary Ligands for Low- and High-Molecular-Weight Organic Ligands Exhibiting Semiconducting Properties 125
2.4 Preparation and Applications of Photopatternable Nanocrystals in the Microfabrication of 2D/3D Functional Structures 131
2.4.1 Nanocrystals with Photocleavable Groups 131
2.4.2 Nanocrystals with Photopolymerizable Groups 135
2.5 Energy and Charge Transfer in Semiconducting Nanocrystal-Based Hybrid Materials 140
2.5.1 Nanocrystal-Decorated Hybrid Materials 140
2.5.2 Nanocrystal-Coupled Hybrid Materials 145
2.6 Synthesis, Electrical/Optical Properties, and Applications of Perovskite Nanomaterials 149
2.6.1 Synthesis of Perovskite Nanocrystals 149
2.6.2 Optical and Electrical Properties of Perovskite Nanocrystals 153
2.6.3 Applications of Perovskite Nanocrystals 153
Acknowledgments 156
References 156
3 Synthesis of High k Nanoparticles by Controlled Radical Polymerization 181
Jiajun Yan, Joanna Pietrasik, Aleksandra Wypych-Puszkarz, Magdalena Ciekanska, and Krzysztof Matyjaszewski
3.1 Introduction to Controlled Radical Polymerization 181
3.2 Surface-Initiated Controlled Radical Polymerization 183
3.3 SI-CRP from Nanoparticles 189
3.3.1 Initiator/Chain Transfer Agent Immobilization on the Particle Surfaces 189
3.3.2 Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP) 190
3.3.2.1 Initiation 190
3.3.2.2 Propagation 190
3.3.2.3 Termination 192
3.3.3 SI-RAFT 193
3.3.3.1 Kinetics of SI-CRP 194
3.4 Materials Prepared via SI-CRP 194
3.5 High k Nanoparticles 197
3.5.1 Materials 197
3.5.2 Applications 199
3.5.3 Need for Polymer Modification 201
3.6 High k Hybrid Materials Prepared via SI-CRP 204
3.7 Summary 210
Acknowledgments 211
References 211
4 Polymer Blending and Phase Behavior in Organic Electronics: Two Case Studies 227
Jasper J.Michels, Alexander Kunz, Hamed S. Dehsari, Kamal Asadi, and Paul W. M. Blom
4.1 Introduction 227
4.2 Calculation of the Ternary Phase Diagram of an Amorphous Mixture 229
4.3 Elimination of Charge Trapping in OLEDs by Polymer Blending 231
4.3.1 Electron Trap Dilution in Organic Light-emitting Diodes 231
4.3.2 Solution-State Demixing and Microstructure Evolution in MEH-PPV: Insulator Blends 232
4.3.3 Operation and Performance of Blend-Based OLEDs 237
4.3.4 Section Summary 239
4.4 Vapor-Induced Demixing in Polymer Films for Organic Memory Devices 240
4.4.1 Processing of Ferroelectric Polymers for Flexible Memory Applications 240
4.4.2 Predictions by Phase Diagram Calculations and Numerical Simulations 241
4.4.3 Film Casting and Morphological Analysis 246
4.4.4 Memory Device Performance 250
4.4.5 Section Summary 251
4.5 General Outlook 252
Acknowledgments 252
4.A Experimental Procedures Relevant to Section 4.3 253
4.B Experimental Procedures Corresponding to Section 4.4 254
References 255
5 Photogeneration of Charge Carriers in Solution-Processable Organic Semiconductors 259
Heinz Bassler and Anna Kohler
5.1 Introduction 259
5.2 Photogeneration in Single-Component Systems 260
5.2.1 The Onsager Treatment and Concept of Autoionization 260
5.2.2 Fullerenes as Models for Molecular Acceptor Materials 262
5.2.3 Conjugated Polymers as Donor Materials 264
5.3 Photogeneration in Donor-Acceptors Systems 268
5.3.1 The Onsager-Braun Model 268
5.3.2 Experimental Characterization Techniques 271
5.4 Discussion of Contemporary Results 274
5.4.1 Forward Electron Transfer at the Donor-Acceptor Interface 274
5.4.2 The “Hot versus Cold” Problem and the Impact of Charge Transfer State 277
5.4.3 Dissociation of Charge Transfer States 279
5.4.3.1 The Importance of Charge Delocalization 279
5.4.3.2 The Effective Mass Model 283
5.4.3.3 Monte Carlo Simulations 287
5.4.4 Charge Recombination 290
5.4.4.1 Geminate Recombination 290
5.4.4.2 Nongeminate Recombination 292
5.5 Conclusions 298
Acknowledgments 299
References 299
6 Charge Carrier Transport in Organic Semiconductor Composites -Models and Experimental Techniques 309
Jarosław Jung and Jacek Ulański
6.1 Introduction 309
6.2 Basic Concepts 311
6.2.1 Fermi Energy, Level, and Surface 311
6.2.2 Density of States 312
6.2.3 Covalent Bonds 312
6.2.4 Organic Molecules 313
6.3 Exciton States 315
6.3.1 Band Structure in Inorganic Crystalline Semiconductors 315
6.3.2 Exciton Band States in Molecular Crystals 317
6.3.3 Exciton States in Organic Amorphous Solids 318
6.3.4 Diffusion of Excitons in Organic Donor-Acceptor Composites 319
6.4 Charge Carriers in Semiconductors 321
6.4.1 Fermi Level and Pseudo-Fermi Level in Doped Inorganic Semiconductors 321
6.4.2 Conductivity and Mobility of Charge Carriers 322
6.4.3 Holstein Model 323
6.4.4 Doped Conjugated Polymers 324
6.4.5 Doped Small-Molecule Organic Semiconductors 325
6.4.5.1 Ionized Pairs and Charge Transfer Complexes 326
6.4.5.2 HOMO and LUMO Level Shift Controlled by Doping 328
6.5 Density of States in Amorphous Organic Semiconductors 330
6.6 Models of Charge Carrier Transport in Organic Semiconductors 333
6.7 Steady-State Currents 335
6.7.1 Drift Current 335
6.7.2 Space-Charge-Limited Current 338
6.7.3 Transport in Trap-Filled Systems 340
6.7.4 Drift-Diffusion Current 341
6.7.4.1 Nonequilibrium State 341
6.7.4.2 Drift-diffusion Current in Heterostructures with Nonuniform Composition 343
6.8 Influence of Semiconductor Morphology on Field-Effect Mobility 344
6.9 Drift-diffusion Current in Organic Heterostructure 346
6.10 Selected Experimental Techniques for Investigation of Charge Carriers Transport 349
6.10.1 Steady-state Experiments 349
6.10.1.1 Space-Charge-Limited Current (SCLC) 349
6.10.1.2 Field Effect 350
6.10.2 Time-domain Experiments 350
6.10.2.1 Time of Flight (TOF) 350
6.10.2.2 Dark Injection Space-Charge-Limited Current (DISCLC) 351
6.10.2.3 Transient Electroluminescence Measurements 351
6.10.2.4 Pulse Radiolysis Time-Resolved Microwave Conductivity (PR-TRMC) 351
6.10.2.5 Carrier Extraction by Linearly Increasing Voltage (CELIV) 351
6.10.3 Alternating Current Experiments 352
6.10.4 Thermoluminescence (TL) and Thermally Stimulated Currents (TSC) 352
6.11 Concluding Remarks 353
References 353
7 Organic Field-Effect Transistors Based on Nanostructured Blends 365
Łukasz Janasz, Jacek Ulański, andWojciech Pisula
7.1 Introduction 365
7.2 Binary Semiconducting Blends 369
7.2.1 Importance and Principles of Ambipolar Charge Transport in Field-Effect Transistors 369
7.2.2 Blends of Conjugated Polymers and Small Molecules 372
7.2.2.1 Bulk Heterojunction Structures 372
7.2.2.2 Vertically Separated Bilayer Structures 376
7.2.3 Blends of Two Conjugated Polymers 378
7.2.4 Blends of Two Small Molecules 385
7.3 Semiconducting Blends of Conjugated Semiconductors and Polymer Insulators in Organic Field-Effect Transistors 391
7.3.1 Concept 391
7.3.2 Vertically Separated Bilayer Structures 393
7.3.3 Laterally Separated Structures 398
7.3.4 Blends for Bendable and Stretchable Transistors 402
7.4 Summary 405
Acknowledgments 406
References 406
8 Organic Light-emitting Diodes Based on Solution-Processable OrganicMaterials 413
Aikaterini K. Andreopoulou,Maria Gioti, and Joannis K. Kallitsis
8.1 Introduction 413
8.2 Basic Characteristics and Recent Trends in Organic Light-emitting Diodes 414
8.3 Photoactive Organic Materials 416
8.3.1 Organic Small Molecules 416
8.3.2 Organic Semiconducting Polymers 419
8.3.2.1 Specific Cases of Semiconducting Fully Conjugated Polymers for PLEDs 419
8.3.2.2 Polyphenylenevinylenes (PPVs) 420
8.3.2.3 Polyfluorenes (PFs) 421
8.3.2.4 Polythiophenes (PTs) 422
8.3.2.5 Polycarbazoles and Other Nitrogen Heteroatom-containing Structures 422
8.3.2.6 Rod-Coil Block Copolymers for PLEDs 423
8.3.2.7 Rigid-Flexible Alternating Polymers 426
8.3.3 Metallocomplexes - Phosphorescent Dopants 428
8.3.3.1 Iridium-containing Phosphorescent Polymers 433
8.3.3.2 White Phosphorescent Polymers 442
8.4 Fabrication of Solution-Processable OLEDs 447
8.4.1 Basic OLED Structure and Operation Principles 447
8.4.2 Techniques and Methods 450
8.4.2.1 Spin Coating 450
8.4.2.2 Gravure Printing 451
8.4.2.3 Inkjet Printing 452
8.4.3 Charge Injection and Transport Layers 453
8.4.4 Electrodes 456
8.4.5 Characterization and Performance Evaluation 458
8.5 Conclusions 464
References 465
9 Organic Photovoltaics Based on Solution-Processable Nanostructured Materials: Device Physics and Modeling 483
Marek Zdzisław Szymański and Beata Łuszczyńska
9.1 Introduction to Modeling of Electronic Devices 483
9.1.1 Methods of Device Modeling 484
9.1.2 Drift-Diffusion Model 487
9.1.2.1 Unidimensional (1-D) Form 492
9.1.2.2 p-n Junction 493
9.1.2.3 Role of the Density of States 496
9.1.2.4 Electrodes and Interfaces 498
9.1.2.5 Total Electric Current 501
9.1.2.6 Realistic Modeling of Devices 502
9.1.3 Optical Modeling 503
9.1.4 Applications to Organic Electronic Devices 506
9.1.5 Matching with the Experiment 510
9.2 Simulation Examples 514
9.2.1 Open-Source Tools for Photovoltaic Device Simulation 516
9.2.2 Simulation of a Bulk Heterojunction Organic Solar Cell 519
9.2.3 Parameter Extraction from Measurements 524
9.3 Conclusions 527
Acknowledgments 528
References 528
10 Solution-Processed Organic Photodiodes 537
Raphaël Clerc, Jean-Marie Verilhac,Mehdi Daanoune, Benjamin Bouthinon, and Jérôme Vaillant
10.1 Introduction 537
10.2 Basic Principles of Organic Photodiodes 539
10.2.1 Physics of Photon Conversion to Electrons in Organic Semiconductors 539
10.2.2 Device Architecture and Operation 542
10.2.3 Device Figure of Merits 544
10.2.3.1 Light Response 545
10.2.3.2 Quantum Efficiency 545
10.2.3.3 Spectral Response 547
10.2.3.4 Linearity 548
10.2.4 Dark Current in Reverse Polarization 549
10.2.5 Noise Equivalent Power 550
10.2.6 Specific Detectivity 550
10.3 State of the Art of Solution-Processed Organic Photodiodes 551
10.3.1 Organic Photodiodes in the Visible Spectral Domain 551
10.3.1.1 Materials and Processes 551
10.3.1.2 Active Layer Thickness 559
10.3.1.3 Blocking Layers 561
10.3.2 Application of Organic Photodiodes to X-ray Imaging 562
10.3.3 Organic Photodiodes Integrated into CMOS Imagers 564
10.3.4 Organic Photodiodes in the NIR Spectral Domain 566
10.4 Device Modeling of Organic Photodiodes 568
10.4.1 Drift Diffusion Models Based on Virtual Semiconductor Approximation 569
10.4.2 Examples of Simulations 570
10.4.3 Beyond the “Virtual Semiconductor Approximation” 573
10.5 Conclusions 575
Acknowledgments 578
References 578
11 Electronic Memory Devices Based on Solution-Processable Nanostructured Materials 591
Jiři Pfleger
11.1 Introduction 591
11.1.1 Classification of Electronic Memory Devices According to Their Functionality 592
11.1.2 Requirements for Electronic Memory Devices in Printed Electronics 594
11.2 Various Principles of Data Storage 595
11.2.1 Resistive Memory 595
11.2.2 Capacitor-Based Memory 598
11.2.3 Transistor Memory 599
11.3 Resistive Memory Operation Mechanisms 603
11.3.1 Permanent Resistive Memory 603
11.3.2 Charge Transfer Mechanism 604
11.3.3 Charge Trapping 605
11.3.4 Conducting Filaments Formation 605
11.4 Materials for Printable Memory Devices 607
11.4.1 Materials for Resistive RAM Devices 607
11.4.2 Polymer Ferroelectrics for OFET Memory Devices 610
11.4.3 OFET Memory Devices with Charge-Trapping Mechanism 612
11.4.4 OFET Memory with Floating Electrode 615
11.4.5 Vertical Transistor OFET Memory Devices 616
11.5 Final Remarks 617
Acknowledgments 618
References 618
12 Intelligent Roll-to-Roll Manufacturing of Organic Electronic Devices 627
Stergios Logothetidis and Argiris Laskarakis
12.1 Introduction 627
12.2 Polymer-Based Organic Photovoltaics 629
12.3 Manufacturing of Organic Electronic Devices by Roll-to-Roll Pilot-to-Production Lines 634
12.3.1 Roll-to-Roll Printing Pilot-to-Production Lines 634
12.3.2 Ultrafast Laser Patterning 636
12.4 In-line Optical Metrology for Quality Control 638
12.5 Conclusions 646
Acknowledgments 647
References 647
Index 655
