Colloidal Quantum Dot Light Emitting Diodes - Meng, Hong

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Résumé :

Preface xi

1 History and Introduction of QDs and QDLEDs 1

1.1 Preparation Route of Quantum Dots 3

1.2 Light-Emitting Characteristics of Quantum Dots 3

1.2.1 Particle Size and Emission Color 3

1.2.2 Quantum Dot Optical Property 4

1.2.2.1 Quantum Surface Effect 4

1.2.2.2 Quantum Size Effect 4

1.2.2.3 Quantum Confinement Effect 5

1.2.2.4 Quantum Tunnelling Effect 5

1.2.2.5 Quantum Optical Properties 6

1.2.3 Core-Shell Structure of QDs 8

1.2.4 Continuously Gradated Core-Shell Structure of QDs (cg-QDs) 12

1.2.5 Typical QDs Materials 14

1.2.5.1 II-VI Semiconductor QDs 16

1.2.5.2 IV-VI Semiconductor QDs 17

1.2.5.3 II 3 -v 2 Semiconductor QDs 17

1.2.5.4 Ternary I-III-VI 2 Chalcopyrite Semiconductor QDs 17

1.2.5.5 Single Element-Based Semiconductor QDs 17

1.3 Application of Quantum Dots on Display Devices 18

1.3.1 The Basic Structure of QDLED 18

1.3.2 Main Factors Affecting QDLED Light Emission 19

1.3.2.1 Auger Recombination (AR) 19

1.3.2.2 Fluorescence Resonance Energy Transfer 21

1.3.2.3 Surface Traps and Field Emission Burst 22

1.3.3 History of QDLED Development 22

1.4 Conclusion and Remarks 27

References 28

2 Colloidal Semiconductor Quantum Dot LED Structure and Principles 33

2.1 Basic Concepts 33

2.1.1 Color Purity 33

2.1.2 Solution Processability 34

2.1.3 Stability 35

2.1.4 Surface States of Quantum Dots 36

2.1.5 Energy Levels and Energy Bands 36

2.1.6 Metals, Semiconductors, and Insulators 37

2.1.7 Electrons and Holes 38

2.1.8 Fermi Distribution Function and Fermi Energy Level 39

2.1.9 Schottky Barrier 39

2.1.10 Energy Level Alignment 40

2.2 Colloidal Quantum Dot Light-Emitting Devices 40

2.2.1 The Basic Structure of QDLED 41

2.2.2 The Working Principle of QDLED 43

2.2.3 Operating Parameters of QDLED 44

2.2.3.1 Turn-on Voltage 44

2.2.3.2 Luminous Brightness 44

2.2.3.3 Luminous Efficiency 44

2.2.3.4 Luminescence Color 45

2.2.3.5 Luminous Lifetime 45

2.2.3.6 QDLED Device Fabrication Process 48

References 48

3 Synthesis and Characterization of Colloidal Semiconductor Quantum Dot Materials 51

3.1 Background 51

3.2 Synthesis and Post-processing of Colloidal Quantum Dots 53

3.2.1 Direct Heating Method and Hot Injection Synthesis Method 53

3.2.1.1 Hot-Injection Method 54

3.2.1.2 Direct Heating Method 55

3.2.2 Precursor Chemistry 56

3.2.3 Ligating and Non-ligating Solvents 56

3.2.4 Mechanism of Nucleation and Growth of Colloidal Quantum Dots 58

3.2.5 Size Distribution Focus and Size Distribution Scatter 59

3.2.6 Crystalline Species-Mediated Growth and Orientation of Nanocrystals Attachment Growth 60

3.2.7 Synthesis Methods and Band Gap Regulation Engineering of Nuclear-Shell Quantum Dots 61

3.2.7.1 Non-alloyed Core-Shell Quantum Dots 63

3.2.7.2 Alloy Core-Shell Quantum Dots 64

3.2.8 Surface Chemistry of Colloidal Quantum Dots 65

3.2.8.1 Covalent Bond Classification Method 65

3.2.8.2 Entropic Ligands 66

3.3 Material Characterization 66

3.3.1 Ultraviolet-Visible (UV-Vis) Absorption and Fluorescence Spectra 67

3.3.2 Nuclear Magnetic Resonance Spectroscopy 69

3.3.3 Fourier Transform Infrared Spectroscopy (FTIR) 71

3.3.4 X-Ray Photoelectron Spectroscopy (XPS) 74

3.3.5 Transmission Electron Microscopy 76

3.3.6 Small-Angle X-Ray Scattering and Wide-Angle X-Ray Scattering 76

3.3.7 X-Ray Diffractometer 77