WOLEDs and Organic Photovoltaics (eBook)

Preface 5
Contents 7
Overview and Highlights of WOLEDs and Organic Solar Cells: From Research to Applications 9
1 Introduction 10
2 White Organic Light-Emitting Devices 11
2.1 Advantages of WOLEDs 11
2.2 Efficiency Characterization of WOLEDs 12
2.3 WOLED Architectures 14
2.3.1 WOLEDs with Single Emitting Layer 15
2.3.2 Phosphorescent WOLEDs 18
2.3.3 Hybrid WOLEDs 19
2.4 Challenges of WOLEDs 20
2.5 Lighting for the Future 21
3 Organic Solar Cells 22
3.1 Basic Working Principle of Organic Photovoltaic Devices 25
3.2 Device Characteristics of an OPV Device 27
3.2.1 Short-Circuit Current 28
3.2.2 Open-Circuit Voltage 28
3.2.3 Fill Factor 28
3.2.4 Power Conversion Efficiency 28
3.2.5 Incident Photon to Current Efficiency 30
3.3 OPV Device Architecture 30
3.3.1 Exciton Blocking Layer 31
3.3.2 Optical Spacer 33
3.3.3 Bulk Heterojunction 34
3.3.4 Low Bandgap Photoactive Materials 36
3.3.5 Tandem Structures 37
3.4 Challenges of OPV Devices 38
4 Conclusions 39
References 39
White-Emitting Polymers and Devices 44
1 Introduction 45
2 Characterization of White Polymer Light-Emitting Devices 45
2.1 Color Quality of White Polymer Light-Emitting Devices 45
2.2 Characterization for WPLED Efficiency 47
3 White Light-Emitting Polymers 51
3.1 WLEPs Containing Blue and Yellow-Orange Chromophores 52
3.1.1 Complementary Colors Based WLEPs Utilizing Singlet Exciton 52
3.1.2 Complementary Colors Based WLEPs Utilizing both Singlet and Triplet Excitons 55
3.2 WLEPs Containing Blue-, Green-, and Red-Emitting Chromophores 57
3.2.1 RGB Primary Colors Based WLEPs Utilizing Singlet Excitons 58
3.2.2 RGB Primary Colors Based WLEPs Utilizing both Singlet and Triplet Excitons 60
4 White Polymer Light-Emitting Devices 64
4.1 WPLEDs Using Dye-Dispersed Polymer Blend 64
4.1.1 WPLEDs Using Fluorescent Dye-Dispersed Polymer Blend 64
4.1.2 WPLEDs Using Phosphorescent Dye-Dispersed Polymer Blend 68
4.2 WPLEDs from All-Polymer Blends 71
4.2.1 WPLEDs from Fluorescent Polymer Blends 71
4.2.2 WPLEDs from Phosphorescent Polymer Blends 73
4.3 WPLEDs from Excimer/Exciplex 75
4.4 WPLEDs from Multiple Emissive Layers 77
4.5 WPLEDs with Functional Charge-Injection/Transport Layers 78
5 Conclusions 83
References 83
Phosphorescent Platinum(II) Complexes for White Organic Light-Emitting Diode Applications 86
1 Introduction 87
2 Working Principle for WOLEDs 88
2.1 Mixing Red-Green-Blue 88
2.2 Mixing Complementary Colors 89
2.3 Emitting Materials with Complementary Colors 90
3 Phosphorescent Platinum(II)-Based Materials 90
3.1 Bidentate Platinum(II) Complexes 92
3.1.1 Cyclometalated Platinum(II) beta-diketonato [(C^N)Pt(O^O)] Complexes 92
3.1.2 Platinum(II) Di(pyridyl)triazolate [Pt(N^N)2] Complexes 95
3.1.3 Platinum(II) Bis(8-hydroxyquinolato) [PtQ2] Complexes 95
3.2 Tridentate Platinum(II) Complexes 97
3.2.1 Platinum(II) Di(2-pyridiyl)benzene [Pt(N^C^N)X] Complexes 97
3.2.2 Platinum(II) 3-(6-(2-naphthyl)-2-pyridyl)isoquinolinyl [(RC^N^N)PtCl] Complexes 101
3.3 Tetradentate Platinum(II) Complexes 102
3.3.1 Platinum(II) Bis(phenoxy)diimine and Schiff Base Complexes [Pt(N2O2)] 102
3.4 Binuclear Platinum(II) Complexes 104
3.5 Polymeric Materials 107
4 Summary 110
References 110
Solid-State Light-Emitting Electrochemical Cells Based on Cationic Transition Metal Complexes for White Light Generation 112
1 Introduction 113
1.1 Features of Light-Emitting Electrochemical Cells 113
1.2 Organization of This Chapter 113
2 Review of Light-Emitting Electrochemical Cells Based on Cationic Transition Metal Complexes 114
2.1 Increasing Device Efficiency 114
2.2 Color Tuning 125
2.3 Lengthening Device Lifetime 127
2.4 Shortening Turn-On Time 128
3 White Light-Emitting Electrochemical Cells Based on Cationic Transition Metal Complexes 134
3.1 Photophysical and Electrochemical Properties of NovelBlue-Green and Red-Emitting Cationic Iridium Complexes 134
3.2 Electroluminescent Properties of White Light-Emitting Electrochemical Cells Based on Host-Guest Cationic Iridium Complexes 138
4 Outlook 140
References 141
Horizontal Molecular Orientation in Vacuum-Deposited Organic Amorphous Films 143
1 Introduction 144
2 Experiments and Calculations 146
2.1 Variable Angle Spectroscopic Ellipsometry 146
2.2 Cutoff Emission Measurement 148
3 Results and Discussion 150
4 Summary 156
References 156
Recent Advances in Sensitized Solar Cells 158
1 Introduction 159
1.1 Disorder in Nanoporous Nanostructured TiO2 Films 159
1.2 Molecular Adsorbents 160
2 Experimental Methods 161
3 Oriented Nanotube Arrays 162
3.1 Disordered Particle Films Versus Oriented Nanotube Films 162
3.2 Orientational Disorder in Nanotube Films 164
4 Molecular Adsorbent Effects 170
5 Conclusions 172
References 173
Implications of Interfacial Electronics to Performance of Organic Photovoltaic Devices 174
1 Introduction 175
2 Importance of Interfacial Studies in OPV Devices 175
3 Conceptual Aspects of Organic-Organic Heterojunction 177
4 Experimental Techniques and Sample Preparation 179
5 Ambient Effects on Copper Phthalocyanine/Fullerene Photovoltaic Interface 181
5.1 UPS Studies on ITO/CuPc/C60 (Without Exposure) 181
5.2 UPS Studies on ITO/CuPc/C60 (with Exposure) 182
5.3 Effect of Exposure to Low Vacuum 183
6 The Role of Deposition Sequence and the Substrate Effect on C60/CuPc and CuPc/C60 Heterojunctions 185
6.1 The Role of Deposition Sequence (CuPc/C60 vs. C60/CuPc) 186
6.2 The Role of Substrate Work Function 188
6.3 Summary on CuPc-C60 Interface 194
7 Metal-Doped Organic Layer as an Exciton Blocker/Optical Spacer 194
7.1 Structural Considerations of Combining Optical Spacer and EBL 194
7.2 The Limitation on Combining Optical Spacer and Exciton Blocker 195
7.3 Effect of Doping the EBL with Metal 196
7.4 Interface Study on Combined Optical Spacer and Exciton Blocker 198
8 Conclusion 200
References 200
Improving Polymer Solar Cell Through Efficient Solar Energy Harvesting 203
1 Introduction 204
2 RR-P3HT:PCBM System 205
2.1 Slow Growth (Solvent Annealing) 206
2.2 Mixed Solvent 216
3 Efficient Inverted Polymer Solar Cells Using Functional Interfacial Layers 224
4 Development of Low Bandgap Polymers for Polymer Solar Cells 230
5 Summary 238
References 238
Index 241