Photoluminescent Materials and Electroluminescent Devices (eBook)

Contents 6
Luminescence: The Never-Ending Story 8
Luminescent Metal-Containing Polymers for White Light Emission 11
Abstract 11
1 Introduction 11
2 Iridium(III)-Based Polymers 13
2.1 Iridium(III)-Based Main Chain Conjugated Polymers 13
2.2 Iridium(III)-Based Side Chain Conjugated Polymers 15
2.3 Iridium(III)-Based Side Chain Non-Conjugated Polymers 22
2.4 Iridium(III)-Based Chelating Polymers 23
2.5 Iridium(III)-Based Dendritic Polymers 25
3 White Light-Emitting Polymers Based on Other Metals 27
4 Conclusions 30
Acknowledgments 32
References 32
Luminescent Iridium Complexes Used in Light-Emitting Electrochemical Cells (LEECs) 34
Abstract 34
1 Introduction 34
2 [Ir(ppy)2(bpy)](PF6) 36
2.1 Syntheses 36
2.2 Photophysics 37
2.3 Devices 41
3 Blue 44
3.1 Efficiency 46
3.2 Stability 49
4 Green 52
4.1 Efficiency 52
4.2 Stability 53
5 Yellow/orange 54
5.1 Efficiency 56
5.2 Stability 57
6 Red 60
6.1 Efficiency 60
6.2 Stability 63
7 White 64
7.1 Host–guest LEECs 65
7.2 Multilayer LEECs 69
8 Conclusions and Outlook 71
Acknowledgments 72
References 72
Platinum and Gold Complexes for OLEDs 75
Abstract 75
1 Introduction and Scope 76
2 Development of Luminescent Platinum(II) Complexes 78
2.1 Platinum(II) Complexes with Bidentate N-Donor Ligands 78
2.2 Platinum(II) Complexes with Tridentate N-Donor Ligands 81
2.3 Cyclometalated Platinum(II) Complexes 82
2.3.1 Cyclometalated Platinum(II) Complexes with Bidentate Ligands 82
2.3.2 Cyclometalated Platinum(II) Complexes with Tridentate Ligands 87
2.3.3 Cyclometalated Platinum(II) Complexes with C^N^N Ligands 88
2.3.4 Cyclometalated Platinum(II) Complexes with C^N^C Ligands 90
2.3.5 Cyclometalated Platinum(II) Complexes with N^C^N and N^N^N Ligands 91
2.3.6 Cyclometalated Platinum(II) Complexes with Tetradentate Ligands 96
3 Luminescent Gold(III) Complexes for OLED Applications 100
3.1 Cyclometalated Gold(III) Complexes with C^N^C Ligands 100
4 Conclusions 108
Acknowledgments 111
References 111
Phosphorescent Neutral Iridium (III) Complexes for Organic Light-Emitting Diodes 118
Abstract 118
1 Introduction 118
2 Photophysics of Cyclometalated Iridium (III) Complexes 120
2.1 Photoexcitation to the Excited States 120
2.2 Excited-State Photophysics 124
2.3 Photophysics in a Condensed State 127
3 Iridium (III) Phosphorescent Emitters 128
3.1 Structures and Syntheses 129
3.2 Color Tuning of Iridium (III) Complexes 130
4 Iridium (III) Phosphors for OLEDs 133
4.1 Green-Emitting Iridium (III) Phosphors 133
4.2 Red-Emitting Ir(III) Phosphors 135
4.3 Yellow- and Orange-Emitting Iridium (III) Phosphors 137
4.4 Blue-Emitting Iridium (III) Phosphors 138
Acknowledgments 140
References 140
Copper(I) Complexes for Thermally Activated Delayed Fluorescence: From Photophysical to Device Properties 148
Abstract 148
1 Introduction 149
1.1 Exciton Harvesting Mechanisms and Historical Developments 149
1.1.1 Fluorescent Emitters 149
1.1.2 Phosphorescent Emitters 150
1.1.3 TADF Emitters 151
2 Luminescent Cu(I) Emitters: A Brief Overview 153
2.1 Mononuclear Compounds 155
2.2 Dinuclear Compounds 157
3 Photophysical Properties—Case Studies 158
3.1 Mononuclear Compounds: Rigidity and Emission Properties 158
3.1.1 Emission and Rigidity Effects 159
3.1.2 Low-Temperature Phosphorescence—High-Temperature TADF 164
3.2 Dinuclear Compounds: Stability and Photophysical Properties 167
3.2.1 Photophysical Introduction 168
3.2.2 Thermally Activated Delayed Fluorescence 171
4 Electroluminescence with Cu(I) Compounds 173
4.1 Introductory Remarks 173
4.2 Literature OLED Examples 174
4.3 OLED Case Study—Solution-Processed Device Achieving nearly 100 % Internal Quantum Efficiency 174
5 Conclusion 177
Acknowledgments 178
References 178
Materials Integrating Photochemical Upconversion 182
Abstract 182
1 Introduction to Photochemical Upconversion 183
1.1 Introduction 183
1.2 Quantifying Photon Upconversion 184
1.3 Scope of Review 187
2 Upconversion in Fluids 188
2.1 Encapsulation 188
2.2 Organogels 190
3 Inert Substrates 191
3.1 Soft Materials 191
3.2 Rigid Materials 192
3.3 Nanoparticles 194
4 Photoactive Substrates 195
4.1 Thin Films 195
4.2 Sensitizer and Acceptor Materials 195
5 Applications and Device Integration 198
5.1 Photovoltaic Devices 198
5.2 Photocatalysis 200
5.3 Fluorescence Imaging 201
5.4 Other Emerging Applications 202
6 Future Directions 203
Acknowledgments 204
References 205
Metal–Organic and Organic TADF-Materials: Status, Challenges and Characterization 207
Abstract 207
1 Introduction: Thermally Activated Delayed Fluorescence 208
1.1 History 208
1.2 Basic Concepts of TADF and Material Design 210
1.2.1 Harvesting Excitons Via Delayed Singlet Emission 210
1.2.2 Minimizing the Singlet–Triplet Splitting Delta EST 211
1.3 Status Quo: Processing Techniques for TADF Emitters 215
1.3.1 Vacuum Versus Solution Processing 215
1.3.2 Processing of Organic Materials 216
1.3.3 Processing of Cu(I) Materials 217
2 Organic Materials: Design Principles and Challenges 218
2.1 Essential Donor Structures 218
2.2 Arylnitriles as Acceptor Moieties 219
2.3 Aryltriazines as Acceptor Moieties 221
2.4 Biaryl Sulfones as Acceptor Moieties 222
2.5 The Prediction of TADF Properties and Outlook 223
3 Cu(I) Complexes: Molecular Structure and Emission Dynamics 224
3.1 Status and Challenges 224
3.2 Mononuclear Copper(I) Complexes 227
3.3 Binuclear Copper(I) Complexes 229
3.4 Emission Dynamics on the Fast Time-Scale 230
3.5 Assessing the Molecular Structure of Cu(I) Complexes with X-ray Absorption Spectroscopy at the Cu K Edge 234
4 Conclusion: Future Challenges for TADF Emitters 237
Acknowledgments 238
References 238
Perovskite Luminescent Materials 246
Abstract 246
1 Introduction 246
2 Optical Properties of 2D Perovskites 248
3 Optoelectronic Properties of 3D Perovskites 252
4 Enhancing the Photoluminescence of Hybrid Perovskites 254
5 Thin Film Deposition Methods 257
6 Hybrid Perovskite Light-Emitting Diodes 260
7 Electroluminescence from 2D Hybrid Perovskites 262
8 Electroluminescence from 3D Hybrid Perovskites 264
9 Summary 270
Acknowledgements 270
References 270
The Rise of Near-Infrared Emitters: Organic Dyes, Porphyrinoids, and Transition Metal Complexes 274
Abstract 274
1 Introduction 275
2 Organic Emitters 276
2.1 Cyanines 276
2.2 Pyrrolopyrrole Cyanines 278
2.3 Squaraines 278
2.4 BODIPYs 280
2.5 Rhodamines 280
2.6 Donor–Acceptor Substituted Chromophores 281
3 Porphyrinoids 281
3.1 Standard and Extended Porphyrins 283
3.2 Porphyrins with Expanded Rings or Modified Pyrrole Connectivity 286
3.3 Bacteriochlorins 287
3.4 Porphyrin Tapes 289
3.5 Linear Porphyrin Oligomers 290
3.6 Phthalocyanines 292
4 Transition Metal Complexes 295
4.1 Complexes of d6 Metal Centers 295
4.1.1 Re(I) 295
4.1.2 Os(II) and Ru(II) 297
4.1.3 Ir(III) 300
4.2 Complexes of d8 Metal Centers 301
4.2.1 Pt(II) and Au(III) 301
4.3 Complexes of d10 Metal Centers 303
4.3.1 Au(I) and Cu(I) 303
5 Conclusions 304
Acknowledgments 307
References 307
Inorganic Phosphor Materials for Lighting 313
Abstract 313
1 Introduction 314
2 Phosphor Converted White Light Emitting Diodes 315
3 Advanced Structural and Dynamical Characterization of Inorganic Phosphor Materials 318
3.1 Energetics of the Activator Ions and the Effect and Importance of the Structure and Dynamics of the Host 318
3.2 Advanced Structural and Dynamical Characterization 321
3.3 Case Studies 321
4 Yellow Phosphors 323
4.1 Garnet Type Host Lattices and YAG:Ce3+ 324
4.2 4f–5d Transitions in YAG:Ce3+ 325
4.3 Thermal Quenching in YAG:Ce3+ 328
4.4 Lattice Vibrations in YAG:Ce3+ 330
4.5 Other Yellow Phosphors 332
5 Blue Phosphors 333
5.1 Blue Phosphors—Oxide Hosts: Phosphates, Silicates, Aluminates 333
5.2 Blue Phosphors—Other Hosts 337
6 Green Phosphors 339
6.1 Green Phosphors—Oxide Hosts: Phosphates, Silicates 339
6.2 Green Phosphors—Other Hosts 342
7 Red Phosphors 346
7.1 Red Phosphors—Oxide Hosts: Phosphates, Silicates, Borates 347
7.2 Red Phosphors—Oxide Hosts: Molybdates, Tungstates, Niobates, and Tantalates 349
7.3 Red Phosphors—Other Hosts 350
Acknowledgments 355
References 355
Organic Light-Emitting Devices with Tandem Structure 360
Abstract 360
1 Introduction 360
2 Tandem OLEDs 361
3 Interconnecting Layers in Tandem OLEDs 362
3.1 Transparent Conductive Layer 362
3.2 Charge Generation Layer Comprising an Electron-Accepting and an Electron-Donating Material 363
4 Electron Injection Layer (EIL) in Tandem OLEDs 366
4.1 Alkali Metal Containing n-Type Dopant 366
4.2 Ultra-Thin Bilayer of Metal and Alkali Metal Halide 367
5 Solution-Processed Tandem OLEDs 368
5.1 Solution- and Evaporation-Processed Hybrid Tandem OLEDs 368
5.2 Solution-Processed Tandem OLEDs with a Fluorescent Polymer 370
5.3 Solution-Processed Phosphorescent Tandem OLEDs 371
6 Conclusion 374
References 374
Light-Emitting Electrochemical Cells: A Review on Recent Progress 377
Abstract 377
1 Introduction 377
2 Operation: The In-situ Formation of a p-n Junction Doping Structure 380
3 Fabrication: Cost-Efficient Processing of Functional and Novel Device Architectures 382
4 Performance: Achieving Fast Turn-On, High Efficiency, and Long Lifetime 388
5 Conclusions and Outlook 392
Acknowledgments 393
References 393