Organic Optoelectronics

Description

Written by internationally recognized experts in the field with academic as well as industrial experience, this book concisely yet systematically covers all aspects of the topic.

The monograph focuses on the optoelectronic behavior of organic solids and their application in new optoelectronic devices. It covers organic electroluminescent materials and devices, organic photonics, materials and devices, as well as organic solids in photo absorption and energy conversion. Much emphasis is laid on the preparation of functional materials and the fabrication of devices, from materials synthesis and purification, to physicochemical properties and the basic processes and working principles of the devices.

The only book to cover fundamentals, applications, and the latest research results, this is a handy reference for both researchers and those new to the field.

Table of contents

Preface XV

List of Contributors XVII

1 Electronic Process in Organic Solids 1
Hongzhen Lin, Fenglian Bai

• 1.1 Introduction 1
• 1.2 Structure Characteristics and Properties of Organic Solids 3
• 1.2.1 Organic Solids 4
• 1.2.2 Molecular Geometries 7
• 1.2.3 Aggregations and Assemblies 7
• 1.3 Electronic Processes in Organic Small Molecules 8
• 1.3.1 Photophysics of Small Molecules 8
• 1.3.1.1 Molecular Orbital Model 8
• 1.3.1.2 Jablonski Diagram 9
• 1.3.1.3 Frank–Condon Principle 10
• 1.3.1.4 Electronic Absorption 11
• 1.3.1.5 Fluorescence and Phosphorescence 13
• 1.3.2 Excitation for Charge and Energy Transfer in Small Molecules 15
• 1.3.2.1 Photoinduced Electron Transfer 15
• 1.3.2.2 Excitation Energy Transfer 18
• 1.4 Some Basic Concepts of Electronic Process in Conjugated Polymers 22
• 1.4.1 Excited States in Conjugated Polymers 24
• 1.4.1.1 Soliton 24
• 1.4.1.2 Polaron 25
• 1.4.1.3 Bipolaron 26
• 1.4.1.4 Exciton 27
• 1.4.2 Interactions between Conjugated Polymer Chains 30
• 1.4.2.1 Bound Polaron Pairs 30
• 1.4.2.2 Excimers 31
• 1.4.2.3 Ground-State Complexes 32
• 1.4.3 Photoinduced Charge Transfer between Conjugated Polymers and Electron Acceptors 32
• 1.5 Carriers Generation and Transport 35
• 1.5.1 Charge Carriers 35
• 1.5.2 Carrier Mobility and Its Measurement 36
• 1.5.3 Mobility-Influencing Factors 37
• References 38

2 Organic/Polymeric Semiconductors for Field-Effect Transistors 43
Qing Meng, Huanli Dong, Wenping Hu

• 2.1 Introduction 43
• 2.1.1 Features of Organic/Polymeric Semiconductors 44
• 2.1.2 Classification of Semiconductors for Organic Field-Effect Transistors 44
• 2.1.3 Main Parameters for the Characterization of Organic/Polymeric Semiconductors 46
• 2.2 Small-Molecular Semiconductors 47
• 2.2.1 P-type Small-Molecular Semiconductors 47
• 2.2.1.1 Polycyclic Aromatic Hydrocarbons 47
• 2.2.1.2 Chalcogen-Containing Semiconductors 53
• 2.2.1.3 Nitrogen-Containing Semiconductors 63
• 2.2.2 n-Type Small-Molecule Semiconductors 65
• 2.2.2.1 Fluorine-Containing Semiconductors 65
• 2.2.2.2 Cyano-Containing Semiconductors 67
• 2.2.2.3 Carbonyl and Imide Semiconductors 68
• 2.2.2.4 Fullerenes 70
• 2.3 Polymer Semiconductors 71
• 2.3.1 p-Type Polymer Semiconductors 72
• 2.3.1.1 Polythiophenes 72
• 2.3.1.2 Thiophene–Heteroacene Copolymers 73
• 2.3.1.3 Other Copolymers 74
• 2.3.2 n-Type Polymer Semiconductors 75
• 2.4 Normal Synthetic Methods for Organic Semiconductors 76
• 2.4.1 Diels–Alder Cycloaddition 77
• 2.4.2 Aldol Reaction 77
• 2.4.3 Stille Reaction 78
• 2.4.4 Suzuki Reaction 78
• 2.4.5 Sonogashira Crosscoupling 79
• 2.4.6 Ullmann Reaction 79
• 2.4.7 Heck Reaction 79
• 2.5 Purification of Organic Semiconductors 80
• 2.6 Outlook 81
• References 81

3 Organic/Polymeric Field-Effect Transistors 95
Chengliang Wang, Lang Jiang, Wenping Hu

• 3.1 Introduction 95
• 3.1.1 Configurations of Organic Field-Effect Transistors 96
• 3.1.2 Working Principle of Organic Field-Effect Transistors 97
• 3.2 Carriers Transport in Organic Field-Effect Transistors 101
• 3.2.1 Molecular Arrangement in Organic Semiconductors 101
• 3.2.2 Charge Transport Models in Organic Semiconductors 104
• 3.2.3 Factors Influencing Charge Transport in the Conducting Channel of Organic Transistors 108
• 3.3 Electrodes, Insulators, and Interfaces of Organic Field-Effect Transistors 109
• 3.3.1 Electrodes 109
• 3.3.2 Insulators 113
• 3.3.2.1 Oxides 113
• 3.3.2.2 Polymers 114
• 3.3.2.3 Self-Assembled Layers 116
• 3.3.2.4 Air Dielectric 116
• 3.3.3 Interfaces 117
• 3.3.3.1 Energy Level Alignment 117
• 3.3.3.2 Interface Compatibility 119
• 3.4 Organic/Polymeric Thin Film Field-Effect Transistors 121
• 3.4.1 Techniques for Thin Film Preparation 121
• 3.4.2 Effect of Thin-Film Microstructure on the Performance of Transistors 122
• 3.4.3 High-Performance Transistors of Small Molecules 126
• 3.4.4 High-Performance Transistors of Conjugated Polymers 133
• 3.4.5 New Techniques for Organic/Polymeric Thin Film Field-Effect Transistors 135
• 3.4.5.1 Self-Assembly 135
• 3.4.5.2 Printing 137
• 3.5 Organic/Polymeric Single Crystal Field-Effect Transistors 140
• 3.5.1 Organic/Polymeric Single Crystals 140
• 3.5.2 Growth of Organic/Polymeric Crystals 140
• 3.5.2.1 Vapor Process for the Growth of Organic Crystals 140
• 3.5.2.2 Solution Process for the Growth of Organic/Polymeric Crystals 142
• 3.5.3 Fabrication Techniques for Organic Field-Effect Transistors of Single Crystals 144
• 3.5.3.1 Electrostatic-Bonding Technique 144
• 3.5.3.2 Drop-Casting Technique 144
• 3.5.3.3 Deposition Parylene Dielectric Technique 146
• 3.5.3.4 Shadow Mask Technique 147
• 3.5.3.5 Gold Layer Glue Technique 148
• 3.5.4 Performance of Organic/Polymeric Single Crystals in Field-Effect Transistors 148
• 3.5.4.1 Organic/Polymeric Crystals 148
• 3.5.4.2 Structure–Property Relationship of Organic/Polymeric Single Crystals 153
• 3.6 Outlook 155
• References 156

4 Organic Circuits and Organic Single-Molecule Transistors 171
Qinqxin Tang, Yanhong Tong, Wenping Hu

• 4.1 Introduction 171
• 4.1.1 Ambipolar Transistors 171
• 4.1.2 Inverter Circuits 173
• 4.1.3 Ring Oscillator Circuits 176
• 4.2 Circuits of Organic Thin Films 178
• 4.2.1 Circuits of Organic Thin Films Based on Ambipolar Transistors 178
• 4.2.2 Circuits of Organic Thin Films Based on Unipolar Transistors 184
• 4.2.3 Complementary Circuits of Organic Thin Films 187
• 4.2.4 Complex Circuits of Organic Thin Films 192
• 4.2.5 Performance Modulation of Organic Thin-Film Circuits 199
• 4.2.6 Analog Circuit Based on Organic Thin-Film Transistors 209
• 4.3 Self-Assembled and Printed Organic Circuits 210
• 4.3.1 Self-Assembled Organic Circuits 210
• 4.3.2 Printed Organic Circuits 213
• 4.4 Circuits of Organic Crystals 216
• 4.5 Single-Molecule Transistors 221
• 4.5.1 Fabrication of Single-Molecule Transistors 222
• 4.5.1.1 Fabrication of Single-Molecule Prototype Devices 222
• 4.5.1.2 Fabrication of Single-Molecule Transistors by Nanogap Electrodes 225
• 4.5.2 Behavior of Single-Molecule Transistors 244
• 4.5.2.1 Temperature- and Length-Variable Transport of Single Molecules 245
• 4.5.2.2 Inelastic Electron Tunneling Spectroscopy of Single Molecules 247
• 4.5.2.3 Transition Voltage Spectroscopy of Single Molecules 251
• 4.5.3 Quanta and Theories of Single-Molecule Transistors 253
• 4.6 Challenges and Outlooks 259
• References 259

5 Polymer Light-Emitting Diodes (PLEDs): Devices and Materials 277
Xiong Gong

• 5.1 Introduction 277
• 5.2 PLEDs Fabricated from Conjugated Polymers 278
• 5.2.1 Device Architecture 278
• 5.2.2 Device Fabrication 278
• 5.3 Accurate Measurement of PLED Device Parameters 279
• 5.3.1 Photopic Luminosity 279
• 5.3.2 Measurement of PLEDs 281
• 5.4 Devices Physics of PLEDs 283
• 5.4.1 Elementary Microscopic Process of PLEDs 283
• 5.4.1.1 Injection 283
• 5.4.1.2 Carrier Transport 284
• 5.4.1.3 Carrier Recombination 284
• 5.4.1.4 Photon Emission 284
• 5.4.1.5 Photon Extraction 285
• 5.4.2 Carrier Transport in PLEDs 285
• 5.4.3 Electronic Characteristic of PLEDs 286
• 5.4.3.1 Current–Voltage Characteristics 286
• 5.4.3.2 Space–Charge-Limited Currents 286
• 5.4.3.3 Injection-Limited Currents 288
• 5.4.3.4 Diffusion-Controlled Currents 288
• 5.4.4 Fowler–Nordheim Tunneling in Conjugated Polymer MIM Diodes 289
• 5.4.4.1 Single Carrier Devices 292
• 5.4.4.2 LED Operating Voltage and Efficiency 293
• 5.4.4.3 Limits of the Model 294
• 5.4.5 Approaches to Improved Carrier Injection 295
• 5.5 Materials for PLEDs 296
• 5.5.1 Conjugated Polymers for PLEDs 296
• 5.5.1.1 Poly(p-phenylenevinylene)s (PPVs) 297
• 5.5.1.2 Polyphenylenes (PPPs) 297
• 5.5.1.3 Polyfl uorenes (PFs) 297
• 5.5.1.4 Polythiophenes (PTs) 299
• 5.5.2 Anode and Cathode 300
• 5.5.2.1 Anodes 300
• 5.5.2.2 Cathodes 301
• 5.5.3 Hole-Injection/Transporting Materials 302
• 5.5.3.1 Hole-Injection Materials 302
• 5.5.3.2 Hole-Transporting Materials 302
• 5.5.4 Electron-Transporting Materials 302
• 5.6 Electrophosphorescent PLEDs 303
• 5.6.1 Energy Transfer 303
• 5.6.2 Electrophosphorescent PLEDs 306
• 5.6.3 Nonconjugated Polymer-Based Electrophosphorescent PLEDs 309
• 5.6.4 Conjugated Polymer-Based Electrophosphorescent PLEDs 316
• 5.7 White-Light PLEDs 323
• 5.7.1 Solid-State Lighting 323
• 5.7.2 Characterization of White Light 324
• 5.7.3 Fabrication of White-Light PLEDs 325
• 5.7.4 Efficient Excitation Energy Transfer from PFO to the Fluorenone Defect 326
• 5.7.5 White Electrophosphorescent PLEDs 328
• 5.7.6 Outlook of White PLEDs 330
• 5.8 Summary 331
• References 331

6 Organic Solids for Photonics 337
Hongbing Fu

• 6.1 Introduction 337
• 6.2 Size Effects on the Optical Properties of Organic Solids 338
• 6.2.1 Exciton Confi nement Effect 338
• 6.2.2 Size-Tunable Emission 339
• 6.2.3 Multiple Emissions 341
• 6.3 Aggregation-Induced Enhanced Emission 342
• 6.4 Composite Solid 344
• 6.5 Outlook 347
• References 348

7 Organic Photonic Devices 351
Hongbing Fu

• 7.1 Introduction 351
• 7.2 Crystalline One-Dimensional (1-D) Organic Nanostructures 352
• 7.2.1 Self-Assembly in Liquid Phase 352
• 7.2.2 Template-Induced Self-Assembly in Liquid Phase 353
• 7.2.3 Morphology Control with Molecular Design 355
• 7.2.4 Physical Vapor Deposition (PVD) 355
• 7.3 Organic Nanophotonics 357
• 7.3.1 Electroluminescence and Field Emission 358
• 7.3.2 Tunable Emission from Binary Organic Nanowires 358
• 7.3.3 Organic 1-D Optical Waveguides 362
• 7.3.4 Lasing from Organic Nanowires 368
• 7.3.5 Organic Photonic Circuits 369
• 7.4 Outlook 371
• References 373

8 Organic Solar Cells Based on Small Molecules 375
Yuze Lin, Xiaowei Zhan

• 8.1 Introduction 375
• 8.1.1 Solar Energy and Solar Cells 375
• 8.1.2 Materials Features for Solar Cells 376
• 8.1.3 Device Confi gurations of Solar Cells 377
• 8.1.3.1 Hamburger Structure 377
• 8.1.3.2 Tandem Structure 378
• 8.2 Small-Molecule Donors 378
• 8.2.1 Dyes 379
• 8.2.2 Oligothiophenes 384
• 8.2.3 Triphenylamine Derivatives 387
• 8.3 Small-Molecule Acceptors 391
• 8.3.1 Rylene Diimides 391
• 8.3.2 Other Nonfullerene Acceptors 393
• 8.4 Donor–Acceptor Dyad Molecules for Single-Component OPVs 395
• 8.5 Conclusions and Outlook 396
• References 397

9 Polymer Solar Cells 407
Huitao Bai, Qinqin Shi, Xiaowei Zhan

• 9.1 Introduction 407
• 9.2 Polymer Donor Materials 408
• 9.2.1 Polyphenylenevinylene (PPV) Derivatives 408
• 9.2.2 Polythiophene Derivatives 410
• 9.2.3 Polyfluorene Derivatives 413
• 9.2.4 Polycarbazole Derivatives 416
• 9.2.5 Polybenzodithiophene Derivatives 417
• 9.2.6 Polycyclopentadithiophene Derivatives 419
• 9.2.7 Metallic Conjugated Polymers 421
• 9.3 Polymer Acceptor Materials 423
• 9.4 Conclusions and Outlook 428

References 429

10 Dye-Sensitized Solar Cells (DSSCs) 437
Lanchao Ma, Xiaowei Zhan

• 10.1 Introduction 437
• 10.2 Small-Molecule Dyes in DSSCs 442
• 10.2.1 Coumarin Dyes 442
• 10.2.2 Triphenylamine Dyes 444
• 10.2.3 Bisfl uorenylaniline Dyes 448
• 10.2.4 Other Dyes 450
• 10.3 Polymer Dyes in DSSCs 453
• 10.4 Dyes in p-Type DSSCs 454
• 10.5 Summary and Outlook 457
• References 459

11 Organic Thermoelectric Power Devices 467
Martin Leijnse, Karsten Flensberg, Thomas Bjørnholm

• 11.1 Introduction 467
• 11.2 Basic Thermoelectric Principles 468
• 11.2.1 The Thermoelectric Effect 468
• 11.2.2 Thermoelectric Efficiency and Figure of Merit 472
• 11.2.3 Optimizing the Figure of Merit 474
• 11.3 Thermoelectric Materials and Devices 476
• 11.3.1 Inorganic Nanostructured Materials 476
• 11.3.2 Single-Molecule Devices 477
• 11.3.3 Devices Based on Polymers 480
• 11.3.4 Devices Based on Small Molecules 482
• 11.3.5 Hybrid and Composite Materials 482
• 11.4 Conclusions and Outlook 483

References 484
Glossary of the book 487
Index 497