Foreword 7
Contents 9
Preface 15
List of Contributors 17
1 Emission and Excitation Mechanisms of Phosphors 19
1.1 Introduction 19
1.2 General Considerations \u2013 Fluorescent Lamps 19
1.3 General Considerations \u2013 Cathode Ray Tubes 20
1.4 Luminescence Mechanisms 21
1.4.1 Center Luminescence 22
1.4.2 Charge Transfer Luminescence 26
1.4.3 Donor Acceptor Pair Luminescence 26
1.4.4 Long Afterglow Phosphors 29
1.5 Excitation Mechanisms 30
1.5.1 Optical Excitation of Luminescence and Energy Transfer 30
1.6 Energy Transfer Mechanisms Between Optical Centers 32
1.6.1 Mechanisms Underlying Energy Transfer 32
1.6.2 Energy Transfer Governed by Electrostatic Interaction 33
1.6.3 Energy Transfer by Higher-order Coulomb Interaction 36
1.6.4 Energy Transfer Governed by Exchange Interactions 37
1.6.5 Cross-relaxation and Energy Transfer 37
1.6.6 Practical Implications 38
1.7 Excitation with High-energy Particles 39
1.8 Electroluminescence (EL) 42
1.8.1 High-voltage Electroluminescence 42
1.8.2 Low-voltage Electroluminescence 44
1.9 Factors Determining the Emission Color 45
1.10 Energy Efficiency Considerations of Important Luminescent Devices 47
1.11 Luminescence Quantum Yield and Quenching Processes 47
1.11.1 The Energy does not Reach the Luminescent Ion 49
1.11.2 The Absorbed Energy Reaches the Luminescent Ion but there are Nonradiative Channels to the Ground State 49
1.11.3 The Luminescence Generated is Absorbed by the Luminescent Material 51
1.12 Acknowledgement 52
2 Quantum Dots and Nanophosphors 53
2.1 Introduction 53
2.1.1 Optical Properties of Quantum Dots 53
2.1.2 Particle in a One-dimensional Potential Well 54
2.1.3 Particle in Three-dimensional Potentials 58
2.1.3.1 Particle in a General Three-dimensional Potential 58
2.1.3.2 Electron in a Coulomb Potential 59
2.1.3.3 The Hydrogen Atom 60
2.2 Density of States in Low-dimensional Structures 61
2.3 Electrons, Holes, and Excitons 63
2.4 Low-dimensional Structures 64
2.4.1 The Weak Confinement Regime 64
2.4.2 The Strong Confinement Regime 65
2.5 Quantum Confinement in Action 67
2.6 Photoluminescence of Quantum Dots Prepared by Wet-chemical Precipitation 70
2.7 Photoluminescence from Doped Quantum Dots 71
2.8 Luminescence of Nano Particles of Rare-Earth Phosphors 73
2.9 Nanoscale Particles for Molecular Imaging 74
2.10 Conclusions 76
2.11 Acknowledgements 76
3 Phosphors for Plasma Display Panels 79
3.1 Introduction 79
3.2 Principle of Operation of Plasma Display Panels 79
3.3 Performance of Applied Phosphors in PDPs 83
3.3.1 Phosphor Efficiency 84
3.3.2 Electronic Transitions Involved in Europium Luminescence 86
3.3.3 Color point and efficiency of the red phosphors 86
3.3.4 Stability and Color Point of BaMgAl(10)O(17):Eu 88
3.4 Summary and Prospects 90
4 Quantum-Splitting Systems 93
4.1 Introduction 93
4.2 Quantum-splitting Phosphors Based on Pr(3+)-activated Fluoride Materials 94
4.3 Quantum-splitting Phosphors Based on Pr(3+)-activated Oxide Materials 100
4.3.1 SrAl(12)O(19): Pr(3+) 101
4.3.1.1 LaMgB(5)O(10) and LaB(3)O(6) Doped with Pr(3+) 103
4.4 The Quantum Efficiency of the Quantum-splitting Process 106
4.5 Limitations of Pr(3+)-based Quantum-splitting Phosphors 109
4.6 Quantum-splitting Phosphors Based on Gd(3+) and Rare Earth Ion-Activated Fluoride Materials 110
4.6.1 The Electronic Energy Level Structure of the Gd(3+) Ion 110
4.6.2 Quantum Splitting in the Gd(3+)-Eu(3+) System 112
4.6.3 Quantum Splitting in the Er(3+)-Gd(3+)-Tb(3+) System 115
4.7 Multiphoton Emission through High-energy Excitation 116
4.8 Applications of Quantum-splitting Phosphors 117
4.9 Conclusions 118
4.10 Acknowledgements 119
5 Scintillators 123
5.1 Introduction 123
5.2 Positron Emission Tomography and Computed Tomography 124
5.2.1 Physical Principles of Positron Emission Tomography (PET) 124
5.2.2 Computed Tomography (CT) 125
5.3 General Requirements for Scintillating Materials Used in Medical Imaging 125
5.4 Scintillators for Pet Application 130
5.4.1 General Description of Phosphors for PET Scintillators 130
5.4.2 Scintillating Composition Used in PET 132
5.4.2.1 Bi(4)Ge(3)O(12) (BGO) 133
5.4.2.2 NaI:Tl(+) 134
5.4.2.3 Lu(2)SiO(5):Ce(3+) (LSO) 134
5.4.2.4 Lu(2)Si(2)O(7):Ce (Lutetium Pyrosilicate, LPS) 135
5.4.2.5 LaBr(3):Ce 136
5.4.2.6 LuI(3):Ce [29\u201331] 137
5.4.3 Other PET Scintillators 137
5.5 Scintillators for CT Application 138
5.5.1 General Description of Scintillators for CT 138
5.5.2 Scintillating Compositions Used in CT 138
5.5.2.1 CdWO(4) [41\u201343] 138
5.5.2.2 (Y,Gd)(2)O(3):Eu(3+) [5] 139
5.5.2.3 Gd(2)O(2)S:Pr(3+) (GOS) [52] 140
5.6 X-ray Intensifying Screens 141
5.6.1 General Description of Scintillators for Intensifying Screens 141
5.6.2 Phosphor Compositions for Use in X-ray Intensifying Screens 141
5.7 FDXD Detectors [54] 142
5.8 Storage Phosphors 142
5.8.1 General Description of Storage Phosphors 142
5.9 Semiconductor Scintillators 145
6 Upconversion Phosphors 151
6.1 Introduction 151
6.2 Theory of Upconversion 155
6.2.1 Absorption and Excitation Spectroscopy 157
6.2.2 Time Evolution of UC Emission 161
6.2.3 Power Dependence of Upconversion 164
6.2.4 Photon Avalanche Effects in Upconversion 168
6.2.5 Determination of the Upconversion Efficiency 171
6.3 Examples 172
6.3.1 Rare Earth Upconverters 173
6.3.2 Transition Metal Upconverters 180
6.3.3 Mixed Rare Earth/Transition Metal Upconverters 183
6.3.4 Organic Upconverters 187
6.3.5 Nanocrystalline Upconverters 189
6.4 Conclusions and Outlook 193
6.5 Acknowledgements 194
7 Luminescent Materials for Phosphor\u2013Converted LEDs 197
7.1 Inorganic Light-Emitting Diodes (LEDs) 197
7.2 White and Colored LEDs 198
7.3 Phosphor-Converted LEDs 201
7.4 Future Trends 206
8 Organic Electroluminescence 209
8.1 Introduction 209
8.2 OLED Fundamentals 210
8.3 Key OLED Trends and Innovations 215
8.3.1 Electroluminescence from Vapor-deposited Organic Films 215
8.3.2 Electroluminescence from Solution-Deposited Organic Films 220
8.4 Prospects for General Illumination 225
8.4.1 A First OLED Lighting Demonstration 226
8.4.1.1 Downconversion for White Light Generation 227
8.4.1.2 Scattering for Outcoupling Efficiency Enhancement 228
8.4.1.3 A Scalable Monolithic Series Architecture 229
8.4.2 Efficiency Challenge for General Illumination 230
8.5 Conclusions 231
8.6 Acknowledgements 232
9 Experimental Techniques 237
9.1 Introduction 237
9.2 Energy of Optical Transitions: Absorption, Excitation, and Emission Spectroscopy 238
9.2.1 Broadband Light Sources 241
9.2.2 Dispersing Elements 242
9.2.2.1 Gratings 242
9.2.2.2 Interferometers 245
9.2.3 Detectors 247
9.3 The Transition Dipole Moment: Absorption Strengths and Luminescence Lifetimes 251
9.3.1 Lasers 253
9.3.2 Luminescence Lifetimes 255
9.4 Quantum Efficiency and Nonradiative Relaxation 256
9.5 Homogeneous Broadening and Dephasing 258
9.6 Detection of Luminescence from Individual Optical Centers 262
9.7 Acknowledgement 266
Index 269