Title Page
Contents
Abstract 7
Chapter 1. Introduction 13
Chapter 2. Experimental section 16
2.1. Materials 16
2.2. Ionogel preparation 16
2.3. Fabrication and characterization of OEGTs 17
2.4. Flexible OEGTs and complementary flexible inverters 18
2.5. Spectroelectrochemistry Measurements 18
2.6. Grazing Incidence Wide Angle X-Ray Scattering 19
Chapter 3. Characterization of BBL-based OEGTs using ionogels as electrolytes 20
3.1. Results and discussion 20
3.1.1. Characterization of BBL-based OEGTs 20
Chapter 4. Unusual phenomena about performance differences depending on the number of cycles in OEGTs 27
4.1. Results and discussion 27
4.1.1. Unusal phenomena observed only when ionogels used as electrolytes in BBL-based EGTs 27
4.1.2. Morphological variations owing to the electrochemical doping in BBL films 31
Chapter 5. Advantages of using solid-state ionogels with nonvolatile properties in OEGTs 41
5.1. Results and discussion 41
5.1.1. Advantages of nonvolatile ionogels as electrolyte 41
5.1.2. BBL-based flexible transistors and inverters using solid-state ionogels 42
Conclusion 53
References 55
Table 3.1. Comparison of device performances of the previously reported BBL-based EGTs. 25
Figure 3.1. (a) Chemical structures of the BBL (top), copolymer (P(VDF-HFP)) and the ionic liquid ([BMI][TFSI]) (bottom). (b) Schematic of the ionogel-gated... 23
Figure 3.2. (a) Typical output curves with five different gate biases. (b) transfer curve of the same device with VD=0.6 V. These EGT measurements were...[이미지참조] 24
Figure 3.3. Linear ID-VG with VD=0.6 V and eru-VG behavior in high VG range. The eru was calculated from gate current-gate voltage (I G-VG). These EGT...[이미지참조] 26
Figure 4.1. (a) Five consecutive ID-VG transfer curves at VD=0.6 V in BBL-based OECT. (b) Variations of the Vₜₕ and hysteresis upon the 5 cycles extracted from...[이미지참조] 33
Figure 4.2. (a) In situ differential UV-Vis absorption spectra under different potentials. The baseline is the spectrum measured after applying 1st doping-...[이미지참조] 34
Figure 4.3. Variations of the Vₜₕ and hysteresis with different scan rate. (a) The scan rate was initially changed from 82 mV/s to 17 mV/s and then changed from... 35
Figure 4.4. Transistor dates when the gate voltage sweep was performed at a slow scan rate first. The scan rate increased in the order of 17, 36, 81, 138, and 156... 36
Figure 4.5. Hysteresis variations as a function of applied maximum VG . The hysteresis is extracted from the second cycle of each ID-VG transfer curve (VD=0.6...[이미지참조] 37
Figure 4.6. (a) Out-of-plane (qz) GIWAXS linecut profiles of BBL films under various experimental conditions. One BBL sample was treated in the order of...[이미지참조] 38
Figure 4.7. Out-of-plane (qz) GIWAXS linecut profiles of BBL thin films doped with increasing voltages (from 0.5 V to 2.0 V).[이미지참조] 39
Figure 4.8. Schematic showing the ion pathway formation mechanism during the electrochemical doping process for high crystalline BBL. 40
Figure 5.1. (a) ID-VG transfer curve (VD=0.6 V) of BBL-based EGT using 0.1 M NaCl solution as electrolyte. The inset shows that the NaCl solution evaporates...[이미지참조] 44
Figure 5.2. ID vs VG transfer curves (VD=0.6 V) of BBL-based EGT using the solvent-cast ionogel obtained at different temperatures of 25, 50, 75, and 100 °C.[이미지참조] 45
Figure 5.3. (a) Optical image and (b) Variations in the on current and Vₜₕ of flexible OEGTs attached on the curved surface having the different curvatures... 46
Figure 5.4. ID-VG transfer curve (VD=0.6 V) of BBL-based EGT fabricated on PET substrate.[이미지참조] 47
Figure 5.5. ID-VG transfer curves (VD= 0.6 V) of the flexible OEGT after the 1000 successive mechanical bending cycles.[이미지참조] 48
Figure 5.6. Schematic of all organic and flexible complementary inverter based on the p-type P3HT and n-type BBL ECTs. 49
Figure 5.7. (a) Typical output characteristic obtained at five different VG, (b) transfer characteristic obtained in saturation region at VD=-0.6 V for the p-type...[이미지참조] 50
Figure 5.8. Voltage transfer characteristics of complementary inverter : (a) Vout vs Vin and (b) Voltage gain of inverter as a function of Vin at three different supply...[이미지참조] 51
Figure 5.9. Transfer curve of the inverter after the bending cycling (100 cycles) to a bending curvature r of 7 mm. 52