Electronic Processes in Organic Electronics (eBook)

Preface 6
Contents 8
Contributors 12
Part I: Bridging Structure, Electronic States and Electrical Conductivity 15
Chapter 1: Fundamental Aspects and the Nature of Organic Semiconductor 16
1.1 Brief History and Technological Applications 16
1.2 Universal Features of Molecular Crystals as the Nature of Organic Semiconductor 17
1.3 What Do We Need for the Next? 21
References 21
Chapter 2: Ultraviolet Photoelectron Spectroscopy (UPS) I: Band Dispersion Measurements of ``Insulating´´ Organic Single Cryst... 23
2.1 Introduction 23
2.2 How to Measure the Band Dispersion in Organic Solids 24
2.3 From Thin Film to Single Crystal 28
References 38
Chapter 3: Ultraviolet Photoelectron Spectroscopy (UPS) II: Electron-Phonon Coupling and Hopping Mobility 39
3.1 Introduction 39
3.2 How to Realize the High-Resolution UPS 41
3.3 Estimation of Charge Reorganization Energy, Polaron Binding Energy and Hopping Mobility 50
3.3.1 Role of Hole-Vibration Coupling in Hopping Mobility 50
3.3.2 Analysis of HOMO Fine Feature 53
References 59
Chapter 4: Ultraviolet Photoelectron Spectroscopy (UPS) III: Direct Study of ``Invisible´´ Band Gap States by Ultrahigh-Sensit... 62
4.1 Introduction to the Role of Band Gap States and Detection by Ultrahigh Sensitivity UPS 62
4.2 Development of Ultralow-Background and Ultrahigh-Sensitivity UPS 65
4.3 Role and Origin of Invisible Gap States 67
4.3.1 Gas Exposure Effects on Pentacene Thin Films 67
4.3.2 Why Does Pentacene Always Show p-Type Property in Device? 72
4.3.3 Contribution of Fully Relaxed Large Polaron 73
4.4 On the Definition of the Mobility Edge and the Charge Transport Gap 76
References 77
Chapter 5: Pentacene Becomes Mott-Hubbard Insulator by Potassium Doping 79
5.1 Introduction 79
5.2 Preparation of Single Crystalline Films of Pentacene 82
5.3 Impact of K Doping on the Film Structure and Energy Levels 83
5.4 Band Dispersion and Formation of Mott-Hubbard Insulator 86
5.5 Conclusions 95
References 95
Chapter 6: Vertical Bonding Distances Impact Organic-Metal Interface Energetics 98
6.1 Introduction 98
6.2 The X-Ray Standing Wave Technique 101
6.2.1 The X-Ray Standing Wave Field 102
6.2.2 The Photoelectron Yield 104
6.3 Physisorption: Interplay of Pauli Repulsion and van der Waals Attraction 105
6.4 Charge Rearrangements of Weakly Interacting Systems 108
6.5 Oxygen Side-Groups Lead to Surface-Induced Aromatic Stabilization 109
6.6 Conclusions 112
References 114
Chapter 7: Structure Matters: Combining X-Ray Scattering and Ultraviolet Photoelectron Spectroscopy for Studying Organic Thin ... 117
7.1 Introduction 117
7.2 X-Ray Scattering 118
7.2.1 X-Ray Reflectivity 118
7.2.2 Grazing Incidence X-Ray Diffraction 119
7.2.3 Coherent Island Size and Scherrer Formula 120
7.3 Probing Depths of X-Ray Scattering and UPS 121
7.4 Example 1: DIP at Different Substrate Temperatures 123
7.4.1 Experimental 124
7.4.2 Results 124
7.4.3 UPS 126
7.5 Example 2: C60 on DIP 128
7.5.1 UPS 130
7.6 Summary 132
References 133
Chapter 8: Photoelectron Yield Spectroscopy for Organic Materials and Interfaces 138
8.1 Introduction of Photoelectron Yield Spectroscopy 138
8.2 Analysis of the Threshold Region of PYS 140
8.3 Detection Methods of Photoemission Yield 144
8.4 Apparatus for PYS measurement 145
8.5 Application of PYS to Organic Materials 146
8.5.1 Examples of PYS for Organic Films and air-Exposure Effect on Their Ionization Energy 146
8.5.2 Application of PYS to Insulating Samples 150
8.5.3 Application of PYS to Liquid Samples 152
8.5.4 Application of PYS to Organic Interfaces 154
8.6 Analysis of an Organic Interface by Combining PYS and low Energy High Sensitivity UPS 159
8.7 Summary 160
References 161
Part II: Organic Devices and Their Properties 163
Chapter 9: Fabrication and Characterization of Organic Devices 164
9.1 Basic Electrical Properties of Organic Films 164
9.2 Fabrication Processes for Organic Films 165
9.2.1 Physical Vapor Deposition 165
9.2.2 Solution Deposition 166
9.2.3 Thermal Press and Thermal Lamination Methods 166
9.3 Characterization of Organic Films 169
9.3.1 Experimental Details of In Situ Field-Effect Measurements 169
9.3.2 Thermally Stimulated Current (Pyroelectric Current Measurement) 174
9.4 Organic Thin Film Transistors 179
9.4.1 Step-Edge Vertical-Channel OFET 179
9.4.2 Self-Aligned Organic Nanochannel Transistors 180
9.5 Flexible Device Application 183
9.5.1 Flexible Transistors 183
9.5.2 RFID Tag 184
9.5.3 Active-Matrix OLED Display 185
References 186
Chapter 10: Mobility Limiting Factors in Practical Polycrystalline Organic Thin Films 190
10.1 Overview of the Morphological Features of Pentacene Thin Films [5] 190
10.2 Extrinsic Limiting Factors of Carrier Mobility in Pentacene Thin-Film Transistors [6] 194
10.2.1 Importance to Know the Influence of Defective Structures 194
10.2.2 Special Measurement Techniques 195
10.2.3 Electrode Contacts 196
10.2.4 Crystal Grains and Grain Boundaries 203
10.3 Intrinsic Limiting Factors of Carrier Mobility in Pentacene Thin-Film Transistors [6-8] 204
10.3.1 Grain-Boundary-Limited Carrier Transport in Polycrystalline Films 204
10.3.2 Estimation of Potential Barriers and In-Grain Mobility 205
10.3.3 Potential Fluctuation Within a Crystalline Domain [8, 9] 208
10.4 A Model to Express the Apparent Carrier Mobility in Practical Thin-Film Transistors 214
10.5 Crystal Order in Pentacene Crystals on SiO2 and its Influence on Electronic Band Structure [10] 215
10.5.1 GIXD Analysis of Pentacene Films Grown at Various Temperatures 215
10.5.2 Origin of the Temperature Independent Small Crystallite Size and Band-Edge Fluctuation 219
10.5.3 Overview of HOMO-Band-Edge and Crystallographic Structures in Pentacene Thin Films 220
10.6 Influence of Chemical Composition of Insulator Surface on Carrier Mobility [11] 221
10.6.1 Surface Chemical Treatments to Improve Carrier Mobility 221
10.6.2 Influence on Film Morphology and Crystallographic Structure 222
10.6.3 Influence on Transistor Characteristics 224
10.6.4 Mobility Limiting Factors Influenced by the Chemical Composition of Insulator Surface 225
10.7 Summary 227
References 229
Chapter 11: Materials for Organic Light Emitting Diode (OLED) 231
11.1 OLED and Phosphorescent Cyclometalated Iridium (III) Complexes 231
11.2 Meridional and Facial Isomers of Iridium Complexes and Their Photochemical Isomerization 233
11.3 Blue Phosphorescent Cyclometalated Iridium (III) Complexes and Their Nonradiative Deactivation 240
11.4 Wet Processable Host Materials for Phosphorescent OLED 248
References 253
Chapter 12: DNA Electronics and Photonics 256
12.1 Structure and Properties of DNA Functional Molecule Complexes 256
12.2 BiOTFT Memory with DNA Complex as Gate Dielectric 259
12.2.1 OTFT Using Bio-Related Materials and DNA-Surfactant Complexes 259
12.2.2 Photo-Electrical Properties of DNA-Surfactant Complexes 261
12.2.3 Fabrication of BiOTFT Devices Using DNA-Surfactant Complexes 266
12.2.4 Summary 267
12.3 BiOLED with DNA Complexes 268
12.3.1 Application of DNA Complexes as Charge Conductive Material 268
12.3.2 Structure of Template Photopolymerized PAn/DNA Complex 269
12.3.3 EL Properties of Ru(bpy)32+-Based DNA BiOLED 273
12.3.4 Color Tunable OLED Based on the DNA/Pan/Ru(bpy)32+ Complex 277
12.3.5 Summary 281
References 282
Part III: Theoretical Study 285
Chapter 13: Theory of Photoelectron Spectroscopy 286
13.1 What Is Special in Theory of Photoelectron Emission from Organic Solids? 286
13.2 Basic Theory 287
13.2.1 Photoemission Intensities Derived from Many-Body Scattering Theory 288
13.2.2 Photoemission Intensities Derived from Keldysh Green´s Functions 289
13.2.3 Phonon Effects: Debye-Waller Factor, Electron-Phonon Interaction 292
13.3 Photoemission from Valence Levels 294
13.3.1 Angle-Resolved Photoelectron Spectroscopy Excited with Low Energy Photons 294
13.3.2 High-Energy Photoelectron Emission 298
13.4 Concluding Remarks 300
References 301
Chapter 14: Theory of Metal-Atom Diffusion in Organic Systems 303
14.1 Introduction 303
14.2 Atomic Impurity States in Organic Solid 304
14.3 Adiabatic Potential and Atom Diffusion 306
14.4 Diffusion between/on Graphene Sheets 309
14.5 Diffusion in Polyacetylene Bundles 312
14.6 Diffusion in Oligoacene Model Solid 312
14.7 Concluding Remarks 315
References 316
Chapter 15: Numerical Approach to Charge Transport Problems on Organic Molecular Crystals 318
15.1 Problems in Charge Transport of Organic Semiconductors 318
15.1.1 Recent Experimental Studies 320
15.1.2 Recent Theoretical Studies 321
15.2 Fundamental Theory of Transport Phenomena in Crystals 322
15.2.1 Electronic States of Molecular Crystals 322
15.2.1.1 Tight-Binding Approximation 322
15.2.1.2 Electronic Band Structure, Carrier Velocity and Effective Mass 324
15.2.2 Electric Conductivity, Mobility and Mean Free Path of Crystals 325
15.2.3 Kubo Formula Based on Quantum Theory 326
15.2.4 Inter- and Intramolecular Vibration Effects 328
15.2.4.1 Holstein Model 328
15.2.4.2 Peierls Model 330
15.2.4.3 Holstein-Peierls Model 330
15.3 Methodology of Charge Transport Calculations for Organic Semiconductors 331
15.3.1 TD-WPD Methodology for Organic Semiconductors 331
15.3.1.1 Conductivity of Electron Coupled with Molecular Vibrations 333
15.3.1.2 Motion of Molecules Coupled with Electrons 333
15.3.1.3 Parameters of Organic Semiconductors 335
15.4 Transport Properties of Carrier Coupled with Inter- and Intramolecular Vibrations of Organic Semiconductors 336
15.4.1 Polaron-Formation Effect on Electronic States 336
15.4.1.1 Binding Energy of Polaron State 337
15.4.1.2 Thermal-Fluctuation and Polaron-Formation Effects on Transfer Energy 338
15.4.2 Inter- and Intramolecular-Vibration Effects on Intrinsic Charge-Transport Properties 339
15.4.3 Static Disorder Effects on Charge Transport 340
15.4.3.1 Temperature Dependence of Carrier Mobility and Mean Free Path 340
15.4.3.2 Time-Scale of Electron Propagation in Organic Semiconductors 342
15.5 Summary 343
15.5.1 Forthcoming Challenges in Theoretical Studies 343
References 344
Part IV: Bridging Different Fields: Challenges for the Future 347
Chapter 16: Function of Conjugated pi-Electronic Carbon Walled Nanospaces Tuned by Molecular Tiling 348
16.1 Introduction 348
16.2 Single- and Double-Wall Nanocarbons 351
16.3 Morphological Defect Structure 354
16.4 In-Pore Super High Pressure Effect 356
16.5 Adsorption-Aided Tuning of Electronic and Interfacial Properties of SWCNT 360
16.5.1 Charge Transfer Interaction 361
16.5.2 C60-Intercalated SWCNT 362
16.5.3 Polycyclic Aromatic Hydrocarbon Intercalated SWCNT 364
16.5.4 Naphthalene-Derivatives Intercalated SWCNT 367
16.5.5 TCNQ-Adsorbed SWCNT 369
16.5.6 Methylene Blue-Encapsulated SWCNT 369
16.5 Conclusions 372
References 372
Chapter 17: Understanding of Unique Thermal Phase Behavior of Room Temperature Ionic Liquids: 1-Butyl-3-Methylimdiazolium Hexa... 376
17.1 Introduction 376
17.1.1 What are Room Temperature Ionic Liquids? 376
17.1.2 Importance of Understanding of Thermal Phase Behavior of RTILs 377
17.1.3 1-Butyl-3-Methylimidazolium Hexafluorophosphate 377
17.2 Thermal Phase Behavior and Molecular Structure of [C4mim]PF6 378
17.2.1 Development of Simultaneous Measurement Apparatus 378
17.2.2 Thermal Phase Behavior of [C4mim]PF6 Investigated with Calorimetry 380
17.2.3 Determination of Ion Structure 383
17.3 Molecular Dynamics of [C4mim]PF6 in the Solid State 387
17.3.1 Cation Dynamics 388
17.3.2 Anion Dynamics 391
17.4 Summary and Perspective 396
References 396
Chapter 18: Single Molecular Spintronics 399
18.1 Introduction 399
18.2 Spin-Polarized STM 400
18.3 Magnetoresistance Through a Single Molecule 406
References 411
Chapter 19: Vortex Lasers Twist Materials to Form Chiral Nanostructures 413
19.1 Introduction 413
19.2 Optical Vortex Lasers 414
19.2.1 Optical Vortex [1-3] 414
19.2.2 How to Produce Optical Vortex Lasers 415
19.3 Optical Vortex Laser Ablation 416
19.3.1 Nanostructure Fabrication [15, 16] 416
19.3.2 Chiral Materials Processing [17, 18] 417
19.3.3 Angular Momentum Effects 419
19.4 Chiral Organic Materials 420
19.4 Conclusion 422
References 423
Index 424