Preface xi
1 A Brief Introduction to Molecular Aggregates 1
Jiaqiang Wang, Juqing Gu, Guigui Ye, Wei Cao, Meng Wang, Changzun Jiang, Shuhui li, Arui Huang, Qianqian li, and Zhen li
1.1 Introduction 1
1.1.1 Motivation 1
1.1.2 A Brief History 4
1.1.3 Basic Knowledge of Organic Compounds in Aggregated States 7
1.1.3.1 The Driving Force of Molecular Aggregates 7
1.1.3.2 The Adjustment of Molecular Interactions in Molecular Aggregates 10
1.1.4 Overview of Topics Covered 13
References 17
2 The Molecular Engineering and Fabrication Processes for Molecular Aggregates 33
Yujie Yang, Boxi Wu, Wentao Yuan, Shiyue Tang, Panpan Qiao, Yifan Niu, Peidong Xie, Ruixing Wang, Yan Gao, Yuexin Li, Wanni Yao, Kai Wang, Qianqian li, and Zhen li
2.1 Crystal Engineering 33
2.1.1 Organic Crystals Grown from Solution 34
2.1.1.1 Solvent Evaporation Method 34
2.1.1.2 Slow Cooling Method 36
2.1.1.3 Vapor Diffusion Method 36
2.1.1.4 Liquidâ"Liquid Diffusion Method 37
2.1.2 Vapor Phase Growth Method 37
2.1.3 Melt Growth 37
2.1.3.1 Bridgmanâ"Stockbarger Method 38
2.1.3.2 Subcooled Melt Method 38
2.1.3.3 Zone-melting Recrystallization 39
2.1.3.4 Czochralski Growth Method 40
2.1.3.5 Laser Heating Base Method 40
2.2 Self-assembly System 41
2.2.1 Drivers of Molecular Self-assembly 41
2.2.1.1 Hydrogen Bonding Interactions 41
2.2.1.2 Hydrophobic Effect 42
2.2.1.3 Electrostatic Interactions 43
2.2.1.4 âÏâ"Ïâ Interaction 43
2.2.1.5 Coordination Interactions 43
2.2.2 Aggregation Types in Molecular Self-assembly 44
2.2.2.1 Nanoparticles 44
2.2.2.2 Membranes 44
2.2.2.3 Micelles 45
2.2.3 Control Methods of Molecular Self-assembly 45
2.2.3.1 Stimuli-responsive Self-assembly 46
2.2.3.2 Solvent Evaporation Self-assembly 46
2.2.3.3 Template-guided Self-assembly 48
2.2.3.4 Adsorption-based Self-assembly 48
2.3 Gel System 49
2.3.1 Chemical Gels 50
2.3.1.1 Free Radical Polymerization 50
2.3.1.2 Dynamic Covalent Cross-linking 51
2.3.1.3 Radiation Cross-linking 52
2.3.2 Supramolecular Gels 53
2.3.2.1 Electrostatic Interactions 53
2.3.2.2 Hydrophobic Interactions 54
2.3.2.3 Crystallization 55
2.3.2.4 Hydrogen Bonding 55
2.3.2.5 Ligand Binding 56
2.3.2.6 Hostâ"Guest Interaction 58
2.4 Cross-linking System 59
2.4.1 Chemical Cross-linking 59
2.4.1.1 Triggered by Chemical Agents 59
2.4.1.2 Triggered by Heat 60
2.4.1.3 Triggered by Light 61
2.4.1.4 Triggered by Radicals 61
2.4.2 Physical Cross-linking 62
2.4.2.1 Physical Entanglement 63
2.4.2.2 Hydrogen Bonding 63
2.4.2.3 Crystallization 63
2.4.2.4 Ionic Interactions 63
2.4.2.5 Self-assembly and Supramolecular Interactions 63
2.4.3 Radiation Cross-linking 63
2.4.4 The Advantages of Cross-linking in the Regulation of Aggregated Structures 64
2.4.4.1 Fixed Orientation and Structural Stability 64
2.4.4.2 Enhanced Mechanical Properties 65
2.4.4.3 Dynamic Covalent Bonding for Adaptive Materials 66
2.5 Hostâ"Guest System 67
2.5.1 Non-covalent Interactions in the Hostâ"Guest System 68
2.5.1.1 Hydrogen Bonding 68
2.5.1.2 Hydrophobic Interactions 69
2.5.1.3 Electrostatic Interactions 69
2.5.1.4 âÏâ"ÏâInteractions 70
2.6 Conclusion 70
References 70
3 The Research Methodology of Molecular Aggregation Science 87
Jiajia Song, Aisen li, Kun Yang, Weilong Che, and Zhen li
3.1 The Theoretical Calculation 87
3.1.1 Introduction 87
3.1.2 Overview of Quantum Chemistry Calculation 88
3.1.2.1 Ab Initio Calculation 89
3.1.2.2 Density Functional Theory 91
3.1.2.3 Semiempirical Molecular Orbital Methods 92
3.1.3 Calculation Software 94
3.1.3.1 Gaussian 94
3.1.3.2 Vasp 94
3.1.4 Calculation of the Properties of Semiconductor Opto-electronic Materials 95
3.1.4.1 Structure Optimization 95
3.1.4.2 Band Structure and Density of States 96
3.1.4.3 Thermodynamic Stability and Chemical Formation Energy 96
3.1.4.4 Carrier Effective Mass 96
3.1.4.5 Optical Absorption Spectrum 99
3.1.4.6 Exciton and Binding Energy of Exciton 100
3.1.5 Conclusion and Outlook 101
3.2 General Methods 102
3.3 Other Methods (Pressure, Light, and Temperature) 108
3.3.1 Pressure 109
3.3.1.1 Mechanical Grinding 110
3.3.1.2 Hydrostatic Pressure 112
3.3.2 Light 114
3.3.3 Temperature 116
3.3.4 Chemical Substances 117
References 119
4 Photoluminescence of Molecular Aggregates 125
Jie Yang, Manman Fang, and Zhen li
4.1 Introduction 125
4.2 Fluorescence 127
4.2.1 Aggregation-induced Emission 127
4.2.2 Excimer 130
4.2.3 J/H/X Aggregate 133
4.3 Thermally Activated Delayed Fluorescence (TADF) 137
4.3.1 Generation of Delayed Fluorescence 137
4.3.2 Aggregation-induced Delayed Fluorescence 138
4.3.3 Through-space Charge Transfer based TADF 141
4.3.4 Exciplex-based TADF 143
4.4 Phosphorescence 145
4.4.1 Room-temperature Phosphorescence 145
4.4.2 Nonaromatic Room-temperature Phosphorescence 149
4.4.3 Long Persistent Luminescence 152
4.5 Conclusion 155
References 155
5 Mechanoluminescence of Molecular Aggregates 163
Yujun Xie, Jinfeng Wang, and Zhen li
5.1 The Emission Mechanism of Mechanoluminescence 163
5.1.1 Brief Introduction to the History of Organic Mechanoluminescence 163
5.1.2 ml Derives from the Gas Discharge of Organic Crystal Without Luminescent Center 165
5.1.3 ml from the Organic Compounds Contain Luminescent Center 167
5.2 Organic Crystals with Fluorescent Mechanoluminescence 169
5.2.1 Triphenylamine Derivatives 169
5.2.2 Tetraphenylethylene Derivatives 172
5.2.3 N-containing Heterocyclic Derivatives 178
5.3 Organic Crystals with Phosphorescent Mechanoluminescence 186
5.4 Mechanoluminescence from Doping System 188
5.5 Special Mechanoluminescence Phenomena 191
5.6 Summary 192
References 193
6 Molecular Aggregates as Charge Transport Layers in Perovskite Solar Cells 199
Shuyan Shao and Zhen li
6.1 Introduction 199
6.2 Construction and Work Principle 202
6.2.1 Device Structure 202
6.2.2 Work Principle 203
6.3 Small Molecules as Hole Transport Layers in HPSCs 204
6.3.1 Chemically Doped Small Molecule HTLs 205
6.3.2 Dopant-free Small Molecule HTLs 218
6.3.2.1 Undoped HTLs in n-i-p Structure 219
6.3.2.2 Undoped HTMs in p-i-n Structure 221
6.4 Small Molecules as ETLs in HPSCs 223
6.4.1 Fullerene and Derivatives 223
6.4.2 Non-fullerene Small Molecules 227
6.4.2.1 Perylene Diimides (PDIs) as ETLs in HPSCs 227
6.4.2.2 NDIs as ETLs in HPSCs 231
6.4.2.3 Azaacene-based Small Molecules as ETLs in HPSCs 233
6.4.2.4 IDT-based Small Molecules as ETLs in HPSCs 234
6.4.2.5 Other Small Molecules as ETLs 237
6.5 Conclusion 238
References 239
7 Molecular Aggregates as Active Layers in Organic Solar Cells 245
Jin He, Yibin li, Zhongâan li, and Zhen li
7.1 Introduction 245
7.1.1 Effects of Donor Aggregates 248
7.1.1.1 Effects of Acceptor Aggregates 259
References 273
8 Molecular Aggregates for Second-order Nonlinear Optical Effect 281
Wenbo Wu and Zhen li
8.1 Microscopic and Macroscopic Nonlinearities of Organic Systems 281
8.2 Organic Molecules for Second-order Nonlinear Optics 284
8.3 Polymers for Second-order Nonlinear Optics 287
8.4 Summary and Perspective 301
Acknowledgements 302
References 302
9 Other Opto-electronic Materials in Aggregate 311
Shaoqiang Dong, Meiting Zhao, Zhijun Ruan, Zekun Tong, Yutian Qin, Chaoyang Zheng, Xinfang Zhang, and Zhen li
9.1 Magnetic Materials 311
9.1.1 Introduction 311
9.1.2 Molecular Magnetic Materials 311
9.1.3 Summary and Perspective 322
9.2 Metalâ"Organic Frameworks 322
9.2.1 Introduction 322
9.2.2 Structure of Opto-electronic MOFs 323
9.2.2.1 TBAPy-based MOFs 324
9.2.2.2 TCBPE-based MOFs 325
9.2.2.3 TCPP-based MOFs 326
9.2.2.4 Other MOFs 328
9.2.3 Properties of Opto-electronic MOFs 330
9.2.4 Summary 332
9.3 Covalent Organic Frameworks 333
9.3.1 Introduction 333
9.3.2 Construction of COFs with Different Aggregation States 334
9.3.3 Properties of COFs with Different Aggregation States 336
9.3.3.1 Optical Properties of COFs 336
9.3.3.2 Semiconducting Properties of COFs 339
9.3.4 Summary and Perspectives 342
9.4 Organic Radical Materials 343
9.4.1 Introduction 343
9.4.2 Triarylmethyl-based Fluorescent Radical Materials 343
9.4.3 âÏ-conjugated Conductive Radical Materials 352
9.4.4 Charged Radical Materials 358
9.4.5 Room-temperature Ferromagnetic Radical Materials 361
9.4.6 Summary and Perspective 362
References 363
10 Conclusions and Outlook 377
Zhen li
Index 379
