Title Page
Abstract
Contents
Chapter 1. Introduction and Motivation 13
1.1. Study Background 14
1.1.1. Organic Electronics 14
1.1.2. Side Chain Engineering 16
1.1.3. Supramolecular Chirality 18
1.2. Research Objectives 20
1.3. References 21
Chapter 2. Role of Side chain engineering in charge transport of DPP-based small molecules and polymers 23
2.1. Introduction 24
2.1.1. DPP Small molecules 24
2.1.2. DPP conjugated polymers 26
2.2. Experimental Section 29
2.2.1. DPP small molecules 29
2.2.2. DPP conjugated polymers 31
2.3. Results and Discussion 36
2.3.1. DPP small molecules 36
2.3.2. DPP conjugated polymers 42
2.4. Conclusion 49
2.4.1. DPP small molecules 49
2.4.2. DPP conjugated polymers 49
2.5. References 51
2.5.1. DPP small molecules 51
2.5.2. DPP conjugated polymers 59
Chapter 3. Role of Side Chain Engineering in DAP-based OFETs and their application in optoelectronic devices 95
3.1. Introduction 96
3.2. Experimental Section 98
3.2.1. Materials and Instrument 98
3.2.2. Thin-Film Microstructure Analyses 98
3.2.3. OFET Fabrication and Measurement 99
3.3. Results and Discussion 101
3.3.1. Materials Synthesis and Characterization 101
3.3.2. Thin-Film Microstructure Analysis 102
3.3.3. Electrical Characteristics of OFETs 103
3.3.4. NIR-Sensing OPTs 104
3.4. Conclusion 109
3.5. References 110
Chapter 4. Studies on Side Chain Engineering in chirality and stacking of PDI-based monomers 127
4.1. Introduction 128
4.2. Experimental Section 130
4.2.1. Synthesis of asymmetric PDI-based chiral molecules 130
4.2.2. Synthesis of symmetric PDI-based chiral molecules and nanowires 131
4.2.3. Thin-Film Microstructure Analyses 131
4.2.4. Structural Characterizations 132
4.2.5. Molecular Dynamics (MD) 132
4.3. Results & Discussion 134
4.3.1. Effect of the spacer length on chirality and stacking manner 134
4.3.2. Effect of conjugation length and alkyl chain on chirality and stacking manner 136
4.4. Conclusion 142
4.5. References 143
요약문 157
Table 2.1. The photophysical and electrochemical properties of DPP small molecules. 90
Table 2.2. 2D-GIXD crystallographic parameters of DPP small molecule films at different annealing conditions. 90
Table 2.3. OFET performance of DPP-based polymer films blow-casted under different annealing conditions. a The maximum mobility of the FET devices (L=50... 91
Table 2.4. Photophysical and electrochemical properties of the polymers. 91
Table 2.5. Calculated dipole moments and energy levels of the dimeric units of the polymers by DFT. 92
Table 2.6. Crystallographic parameters of phosphonate DPP polymer films on OTS- treated substrates. 92
Table 2.7. Electrical characteristics of p-type devices of phosphonate DPP polymers. The maximum mobility of the FET devices (L=50 µm and W=1000 µm). The... 93
Table 2.8. Electrical characteristics of the p-type devices fabricated using OTS-untreated substrates. 93
Table 2.9. Crystallographic parameters of phosphonate DPP polymer films on OTS-untreated substrates. 94
Table 2.10. Electrical characteristics of the p-type devices fabricated using MeTHF. 94
Table 3.1. Photophysical and Electrochemical Properties of DAP-Based Copolymers. 125
Table 3.2. Crystallographic parameters of as-cast films and films annealed at 150 ℃. 125
Table 3.3. Summary of hole mobility, reliability factors and threshold voltage of PDAP-based OFETs with different annealing temperature. The maximum mobility... 126
Table 3.4. Summary of hole mobility, reliability factors, and threshold voltage of PDAP-based OFETs. 126
Table 3.5. Optoelectronic characteristics of phototransistors based on PDAP-Fu, PDAP-Th, and PDAP-Se films. 126
Table 4.1. TD-DFT calculations of symmetric PDI molecules. 156
Figure 2.1. Structure of DPP small molecules used in this study. 77
Figure 2.2. Representative n-type DPP-based small molecules used for OFET applications. 77
Figure 2.3. (a,b) UV-vis-NIR absorption spectra and (c) cyclic voltammograms. 78
Figure 2.4. DFT-optimized geometries and charge-density isosurfaces. 78
Figure 2.5. UV-Vis-NIR absorption spectra of the thermally annealed films of (a) C2C9CN, (b) SiC4CN, and (c) EH4PCN. 79
Figure 2.6. (a) TGA and (b) DSC curves. 79
Figure 2.7. Contact angle measurements of the pristine films. 80
Figure 2.8. AFM height images. Rrms is rms roughness of film. Scale bar=1 μm.[이미지참조] 80
Figure 2.9. 2D-GIXD images of the films. 81
Figure 2.10. GIXD images of the DPP small molecule films converted into the planar figure of the 3D figure cut. 81
Figure 2.11. Transfer curves of the n-type devices of DPP small molecules. 82
Figure 2.12. The output curves of the DPP small molecule-based FET devices. 82
Figure 2.13. Absorption profiles of the polymers (a) in dilute chlorobenzene solution and (b) as thin films on a quartz plate. 83
Figure 2.14. Cyclic voltammograms of the polymer films in n-Bu₄NPF₆/CH₃CN solution (scan rate, 100 mV s⁻¹). 84
Figure 2.15. DFT calculation results: illustrated dipole moments on the energy-minimized structures (top) and charge-density isosurfaces for the model system... 84
Figure 2.16. AFM height images (3 x 3 μm²) of the polymer films. R RMS is rms roughness of the film. Scale bar=1 μm. 85
Figure 2.17. 2D-GIXD images of the polymer films. 85
Figure 2.18. 1D linecut profiles of the 2D-GIXD images of films on OTS-treated substrates. 86
Figure 2.19. Transfer curves of the p-type devices with (a) as-spun and (b) annealed polymer films fabricated using polymer solution in chloroform on OTS-treated substrate. 86
Figure 2.20. The output curves of the phosphonate polymer-based FET devices with (a) as-spun and (b) annealed polymer films. 87
Figure 2.21. The output curves of the phosphonate polymer-based FET devices fabricated using (a) OTS-untreated substrate and (b) polymer solution in MeTHF. 87
Figure 2.22. Transfer curves of the p-type devices fabricated using (a) polymer solution in chloroform and OTS-untreated substrate and (b) polymer solution in... 88
Figure 2.23. AFM height images of the polymer films on OTS-untreated substrates. 88
Figure 2.24. 2D-GIXD images of the polymer films on OTS-untreated substrates. 89
Figure 2.25. 1D linecut profiles of the 2D-GIXD images of the polymer films on OTS-untreated substrates. 89
Figure 3.1. (a) Distribution of frontier molecular orbitals and their energy levels. (b) Electrostatic surface potential for DPP and DAP. (c) Synthetic routes and chemical... 117
Figure 3.2. Normalized UV-vis-NIR absorption spectra (a) in chloroform solution and (b) as thin films. (c) Cyclic voltammograms with the internal standard of... 118
Figure 3.3. Two-dimensional GIXD images and 3 x 3 μm scaled AFM height images (upper-right) of (a) PDAP-Fu, (b) PDAP-Th, and (c) PDAP-Se thin films thermally... 119
Figure 3.4. AFM height images (3 x 3 μm) of before (bottom) thermal treatment of (a)PDAP-Fu, (b) PDAP-Th, and (c) PDAP-Se films. The polymer films were formed... 119
Figure 3.5. 2D-GIXD images for as-cast films of (a) PDAP-Fu (b) PDAP-Th, and (c) PDAP-Se. The films are fabricated by the spin-coating method on OTS modified... 120
Figure 3.6. X-ray diffractogram profiles of (a) in-plane and (b) out-of-plane of as-cast thin films of DAP-based copolymers. 120
Figure 3.7. Transfer characteristics of (a) PDAP-Fu, (b) PDAP-Th, and (c) PDAP-Se. 121
Figure 3.8. Transfer characteristics of PDAP-Fu, PDAP-Th, and PDAP-Se in (a) as cast films and (b) annealed films at 100 ℃. The polymer films were formed by spin-... 121
Figure 3.9. (a) Schematic illustration of BGTC phototransistor devices. (b) Transfer curves in the dark (black line) and under 1060 nm light irradiation (red line) of... 122
Figure 3.10. EQE spectra of the DAP-based photodetectors at -100V in various wavelengths (405 nm, 532 nm, 670 nm, 940 nm, and 1060 nm). 123
Figure 3.11. The linear dynamic range (LDR) for the OPTs measured at -100V with 1060 nm, (a) PDAP-Fu, (b) PDAP-Th, and (c) PDAP-Se. 123
Figure 3.12. Single normalized cycle of the phototransistor for estimating both rise time and fall time. (a) PDAP-Fu, (b) PDAP-Th, and (c) PDAP-Se. 124
Figure 3.13. FT-IR spectra of DAP-based copolymers under 1060 nm light and ambient condition. 124
Figure 4.1. Schematic illustration of the synthetic procedures of chiral PDI molecules starting from PTCDA. 147
Figure 4.2. SEM images of R-1-symPDI and R-2-symPDI. 148
Figure 4.3. CD spectroscopy of the PDI molecules in monomeric state. All molecules were dissolved in CF (10⁻⁴ M). (a) Monomer chirality of R-1-sym (light... 148
Figure 4.4. Transfer characteristics of OFETs fabricated with R-1-sym (left) and R-2-sym (right), via thermal evaporation. 149
Figure 4.5. AFM images of thermally evaporated films of R-1-sym (left) and R-2-sym (right). Scale bar=1μm. 149
Figure 4.6. Molecular design of asymmetric and symmetric chiral PDI molecules. Colored circles indicate the point chirality of each monomer. (green : cyclohexane,... 150
Figure 4.7. Normalized UV-vis absorption spectra of symmetric PDI molecules. Solid lines show monomer state, and dashed lines show NW state. (a) R-1-symCH,... 151
Figure 4.8. DFT calculations (LUMO, HOMO) of R-1-symCH (left), R-1-sym (middle), and R-1-symNT (right). 151
Figure 4.9. Monomer chirality of R-1-symCH/R-1-asyCH, R-1-sym/R-1-asy, R-1-symNT/R-1-asyNT. Symmetric molecules are shown in light solid lines while... 152
Figure 4.10. Orbital correlation diagram and rotational strength calculated with TD-DFT. 152
Figure 4.11. NW chirality of symmetric PDI molecules. Solid line : R enantiomers, dashed line : S enantiomers. 153
Figure 4.12. OM images of symmetric PDI molecules. 153
Figure 4.13. SEM images of symmetric PDI molecules. 154
Figure 4.14. Transfer characteristics of symmetric PDI molecules. 154
Figure 4.15. AFM images of symmetric PDI molecules. Scale bar=1μm. 155
Figure 4.16. SEM images of asymmetric PDI molecules. Top : R enantiomers, bottom : S enantiomers. 155
Figure 4.17. AFM images of asymmetric PDI molecules. Scale bar=1μm. 156
Figure 4.18. Transfer characteristics of asymmetric PDI molecules. 156