Electrical characteristics of DPP-TVT-0 OFET devices at annealing temperatures of 150 °C (a, c), or 250 °C (b, d) in the p-channel (left panel), and n-channel (right panel) operating modes. Electrical characteristics for the DPP-TVT-1 OFET devices at the annealing temperatures of 150 °C (a, c), or 250 °C (b, d) in the p-channel (left panel), and n-channel (right) panel) operating modes. Electrical characteristics for the DPP-TVT-2 OFET devices at the annealing temperature of 150 °C (a, c), or 250 °C (b, d) in the p-channel (left panel), and n-channel (right) panel) operating modes.
List of tables
List of Schemes
Synthetic routes to monomers and chemical structure of PDPP-BZ, PDPP-FBZ polymers
Synthetic routes to monomers and chemical structures of PDPP-Hg, PDPP-DA polymers
Synthetic routes of monomers (a) and chemical structures of DPP-TVT-n (b)
Nomenclature
BM [6,6]phenyl-C71-butyric acid methyl ester ODCB o-dichlorobenzene
ChapterⅠ. Introduction
General Concepts of Diketopyrrolopyrrole-Based Polymers
To compensate for this limited solubility, they replaced the bulky hexadecyl side group, which enables high molecular weight polymer to be obtained, and explored the effect of changing molecular weight using different catalyst Pd2(dba)3/PPh3 versus Pd( PPh3)4. PDPP3T polymer exhibited high power conversion efficiency (PCE) about 4.7 % in case of high molecular weight (Mn = 54 kDa). Alternatively, the low molecular weight case (Mn = 10 kDa) just showed 2.7%.6 In an extension of this work, they reported benzene-containing DPP polymer (PDPPTPT) (see Figure 4) which could lower the HOMO energy level compared to PDPP3T.
DPP-Based Polymers for Organic Field Effect Transistors
- Introduction
- Synthesis and Characterization
Figure 6 shows the absorption spectra of PDPP-BZ and PDPP-FBZ in solution (a) and in the solid state (b). Notably, the absorption spectra of PDPP-FBZ in solution and solid state are clearly red-shifted compared to PDPP-BZ. UV-Vis-NIR absorption spectra of PDPP-BZ, PDPP-FBZ polymers (a) In dilute chloroform solution and (b) as thin films on a quartz plate.
Wavelength (nm)
PDPP-BZ PDPP-FBZ
Photovoltaic device consisting of PDPP-BZ and PDPP-FBZ with [6,6]phenyl-C71-butyric acid methyl ester (PC71BM) in a 1:2 weight ratio is fabricated with an active layer spin coating using the mixture of o-dichlorobenzene (ODCB) ) and chloroform (CF). As for PDPP-FBZ cell, the Voc was increased from 0.73 to 0.84 V, which was attributed to the increase of HOMO energy level and optimized dust state. The whole trend of the spectra of both polymers is in good agreement with J-V curves, which show slightly lower PDPP-FBZ peak than PDPP-BZ. a) J-V characteristics of OPVs based on PDPP-BZ, PDPP-FBZ:PC71BM under illumination of AM.
Current density(mA/cm2)
Voltage(V)
Chapter Ⅲ. The Synthesis of DPP Polymers Containing Triple Bonds and Mercury
- Introduction
- Synthesis and Characterization
To improve the performance of organic photovoltaics (OPVs) based on the organic materials, many scientists have approached the developments through the variation of designed factors. The effective key strategy to improve power conversion efficiency (PCE) is the synthesis of new donor materials. The donor material for narrow band gaps can have the capacity of a wide range of solar spectrum between 300nm ~ 1000nm.
This means that massive amounts of light sources from the sun can be absorbed leading to high s.a. However, due to the limits of the theoretical light-harvesting capacity, some groups have considered modifying the internal interface materials which affect the electron-harvesting properties. DPP polymer with mercury (PDPP-Hg) and DPP polymer surrounded by diacetylene (PDPP-DA) were prepared to investigate the intrinsic properties of mercury in the case of the combined DPP unit.
The synthetic routes to prepare the monomers and PDPP-Hg, PDPP-DA polymers are shown in Scheme 2. To start preparing the polymers, compound 1, 2 was easily synthesized according to the reported literature.17 In In the aftermath of this synthesis, compound 3 was prepared via sonogashira cross-coupling reaction using compound 2 in the mixture of anhydrous THF and diisopropylamine with trimethylsilylacetylene, catalytic amount of CuI, and Pd(pph3)4 as a catalyst at 35 °C for 3 hours. The PDPP-Hg, PDPP-DA polymers have bulky alkyl side chain to improve solubility, on the contrary, general bulky alkyl side chain substituted DPP polymers, which are poorly soluble in common organic solvents, including chloroform, chlorobenzene and dichloromethane, only slightly soluble in THF.
The new PDPP-Hg polymer exhibits slightly lower molecular weights (Mn = 12.2 kDa) and an extremely broad disperse molecular weight distribution of 11.9 compared to the fluorene-based polymers in the previous literature (PFEO-Hg, Mn = 20 kDa, PDI PFEN- Hg, Mn = 18.4 kDa, PDI = 2.1).16 The PDPP-DA polymer also exhibits low molecular weights Mn = 8.6 kDa and a high polydispersity index (PDI) value of 4.6 according to gel permeation chromatography (GPC).
The synthetic routes to monomers and chemical structures of PDPP-Hg, PDPP-DA polymers
The UV-Vis-NIR absorption spectra of the polymers are shown in Figure 8 (THF solution (a) and solid state (b)). The most distinct broad peak is observed in PDPP-DA which is the bathochromatic shift (~120 nm) in PDPP-Hg. From the edge point of these spectra, we can calculate the optical energy gaps of PDPP-Hg, PDPP-DA (Egopt = 1.48 eV, 1.74 eV), respectively.
In general, absorption spectra of both polymers are relatively hypsochromically shifted than typical DPP-based polymers. It is expected that the result of the low molecular weight of polymers and imperfect conjugated form.6 As a result, the PDPP-Hg showed quite large band gaps than common semiconducting organic materials for electronic devices. UV-Vis-NIR absorption spectra of PDPP-Hg, PDPP-DA polymers (a) In dilute THF solution and (b) as thin films on a quartz plate.
PDPP-DA PDPP-Hg
Introduction
- Synthesis and Characterization
- Optical and Electrochemical Properties as well as Theoretical Calculations
- Electrical characterization and performance of OFETs
All polymers were found to have satisfactory Mn values; the rather moderate Mn found for DPP-TVT-2 can be attributed to its reduced solubility due to the increased thiophene content in the backbone. Consequently, the optical band gaps from the onset of absorption of the polymer films follow the order: DPP-TVT-2 > DPP-TVT-1 > DPP-TVT-0, which is an opposite trend compared to the magnitude of the extension of the donor conjugation, which increases as the number of thiophene rings in the repeat unit increases. Top-gate/bottom-contact (TG/BC) OFETs were fabricated using DPP-TVT-n polymers as the active layer.
However, in the cases of DPP-TVT-1 and DPP-TVT-2, the temperature dependence was not as intense as with DPP-TVT-0. Summary of OFET electrical characteristics for DPP-TVT-0, DPP-TVT-1, and DPP-TVT-2 in top/bottom gate contact configurations at different annealing temperatures (Ta = 150 and 250 °C). Summary of OFET electrical characteristics for DPP-TVT-T0, DPP-TVT-1, and DPP-TVT-2 in top/bottom gate contact configurations at the optimal annealing temperature (Ta = 200 °C).
To gain a greater understanding of the correlation between crystal microstructures and charge transport properties, grazing incidence X-ray diffraction (GIXD) experiments of as-spun and annealed DPP-TVT-n thin films were performed. . The annealing temperatures of DPP-TVT-0, DPP-TVT-1, and DPP-TVT-2 were all fixed at 200 °C, at which each sample showed the best electrical properties. More interestingly, the (010) diffraction peaks weakened or disappeared in the out-of-plane GIXD profiles after annealing (see Figure 15 for 1D-GIXD), especially in the annealed DPP-TVT-1 and DPP-TVT-2 films. , implying the favored change of orientation from the frontal structure to the edge structure.
Notably, the interwoven polymer fibers were observed for the annealed DPP-TVT-2 film surfaces (see Figure 18). Conversely, the smaller distance resulting from the absence of the thiophene spacers in DPP-TVT-0 could disrupt the alignment of the side chains toward the backbone, resulting in a less ordered molecular organization. The b-h2 curves of the annealed DPP-TVT-n thin films extracted from GIXD data are included in Figure 19(a) and the crystallographic parameters are listed in Table 5.
DPP-TVT-0 DPP-TVT-1 DPP-TVT-2
Experimental Section
- Materials
- Instrumentations
- Device Fabrication and Characterization
- Synthesis of monomers and PDPP-BZ, PDPP-FBZ polymers
- Synthesis of monomers and PDPP-Hg, PDPP-DA polymers
- Instrumentations
- Device Fabrication and Characterization
- Synthesis of monomers and DPP-TVT-n polymers
The crude product was purified by chromatography on silica eluting with 0–50% dichloromethane in hexane. The organic layer was dried over MgSO4 and the solvent was evaporated under reduced pressure. The crude product was purified by column chromatography using ethyl acetate:hexane (1:10) as eluent to give 1.3 g (83%) of a dark purple solid.
The biphasic system was stirred rapidly overnight at r.t., after which the product was extracted with methylene chloride. DFT calculations were performed using the Gaussian 09 package with the nonlocal hybrid Becke three-parameter Lee-Yang-Parr (B3LYP) functional, and the 6-31G basis set to elucidate the HOMO and LUMO levels after optimization of the geometry of DPP-TVT-0, DPP-TVT-1 and DPP-TVT-2 using the same method. The polymer solution was prepared in 5 mg ml -1 chlorobenzene for DPP-TVT-0, DPP-TVT-1 and DPP-TVT-2.
The DPP-TVT-0, DPP-TVT-1 and DPP-TVT-2 solutions were spin-coated onto gold films. The X-ray incident angle was adjusted to 0.10°, which is just below the critical angle for DPP-TVT-n. The reaction mixture was stirred at room temperature overnight and the solvent was removed under reduced pressure.
The crude product was purified using chromatography on silica with 0-50% dichloromethane in hexane used as eluent.
Chapter Ⅵ. References
C.; Hello.; Li, G.; Yang, Y., Systematic investigation of low-bandgap polymers based on benzodithiophene and diketopyrrolopyrrole designed for single-junction and tandem polymer solar cells. Bürgi, L.; Turbiez, M.; Pfeiffer, R.; Bienewald, F.; Kirner, H.-J.; Winnewisser, C., High-mobility ambipolar near-infrared light-emitting polymer field-effect transistors. Liu, S.; Zhang, K.; Lu, J.; Zhang, J.; Yip, H.-L.; Huang, F.; Cao, Y., High-efficiency polymer solar cells incorporating amino-functionalized conjugated metalpolymer as cathode interlayer.
Kim, D.-Y., Optimal Ambipolar Charge Transport of Thienylenevinylene-Based Polymer Semiconductors by Changes in Conformation for High Performance Organic Thin Film Transistors and Inverters. D.; Heeney, M.; McCulloch, I.; Sirringhaus, H., High-performance ambipolar diketopyrrolopyrrole-thieno[3,2-b]thiophene copolymer field-effect transistors with balanced hole and electron mobility. Dithienosilole/Dithienogermole Copolymers for Efficient Solar Cells: Information from Structure-. Property-Device Performance Correlations and Comparison with Thieno[3,4-c]pyrrole-4,6-dione Analogues.
Kim, Y.-H.; Kwon, S.-K., Effect of Selenophene in DPP Copolymer Incorporating Vinyl Group for High-Performance Organic Field-Effect Transistors. He, M., Scalable Synthesis of Thiophene and Diketopyrrolopyrrole Coupled Semiconducting Polymers Processed from Nonchlorinated Solvents into High-Performance Thin-Film Transistors. A.; Ghibaudo, G., Direct evaluation of low-field mobility and access resistance in pentacene field-effect transistors.
대학원에 입학하고 합성실험을 하면서 어려운 시기도 많았지만, 연구실에 계신 선배, 후배님들께서 많은 도움을 주시고, 믿고 맡겨주셔서 이렇게 졸업할 수 있어서 정말 감사드립니다.
