Synthesis and characterization of donor-acceptor π-conjugated polymers for studying their charge transport properties
- 주제(키워드) Thin-film transistor , Diketopyrrolopyrrole , Conjugated polymer
- 발행기관 고려대학교 대학원
- 지도교수 최동훈
- 발행년도 2014
- 학위수여년월 2014. 8
- 학위구분 석사
- 학과 일반대학원 화학과
- 원문페이지 102 p
- 실제URI http://www.dcollection.net/handler/korea/000000051714
- 본문언어 영어
- 제출원본 000045808530
초록/요약
Organic thin film transistors (OTFTs) have high potential to be applicable to the next generation of soft electronic devices due to their flexibility, light weight and low-cost manufacturing process at large area. However, there is a problem that the charge transport property of the organic material-based devices is inferior to that of inorganic devices. In order to overcome the shortcoming, there have been intensive reports on changes in manufacturing process, development of new materials containing flat conjugative moieties such as diketopyrrolopyrrole (DPP), isoindigo (IID), thienopyrroledione (TPD) and so on. In this study, four different DPP-based donor-acceptor conjugated polymers were synthesized and their properties were investigated. The polymers consist of alternate electron rich unit (donor) and electron deficient unit (acceptor) which can derive extensive delocalization of -electron along their backbone. Firstly, pyrene was selected as a donor unit because of its planar structure which can induce strong propensity for π-π stacking. Two new pyrene containing conjugated polymers were designed and synthesized. By changing the anchoring position of dithienyl DPP from 1,6- to the 2,7-position of the pyrene ring, the energies of the molecular frontier orbitals of the substituted polymers were successfully tuned. The organic thin-film transistors made of the P(DTDPP-alt-(2,7)PY) exhibited higher mobility (0.23 cm2 V–1 s–1) than that obtained using P(DTDPP-alt-(1,6)PY) due to more favorable edge-on orientation of polymer chains on the substrate. Secondly, the tellurophene unit was selected as a strong donor in the polymer repeating group. Polytellurophenes could be capable of supramolecular interactions owing to strong Te-Te interactions. Also, tellurophene has a narrow HOMO-LUMO band gap which could lead to red-shifted optical absorptions compared to those of polythiophenes. However, despite of advantages of tellurophene, a limited number of studies have been reported to date. The reason is that the synthesis of tellurophene moiety is very difficult to conduct. Despite the difficulties, tellurophene-containing conjugated polymer was successfully synthesized via Stille coupling reaction. As expected, tellurophene-containing polymer exhibited a high hole carrier mobility of 1.47 cm2 V-1 s-1. In brief, donor-acceptor type conjugate polymers were synthesized for Organic thin-film transistors (OTFTs). The diketopyrrolopyrrole (DPP) unit has been studied extensively due to their planar structure and specific molecular interaction. Thermal analysis, cyclic voltammetry, absorption spectroscopy and morphological analysis were employed to investigate their intrinsic properties. Eventually, thin film transistors were fabricated to study their semiconducting property.
more목차
CHAPTER 1: Introduction to Organic Thin Film Transistors
1.1. Organic Semiconducting Materials and Their Thin Film Transistors 2
1.1.1. Donor-Acceptor π-Conjugated Polymers 2
1.1.2. Diketopyrrolopyrrole-based Donor-Acceptor Type Polymers 3
1.2. Organic Thin Film Transistors 7
REFERENCES 12
CHAPTER 2: Diketopyrrolopyrrole-based Donor-Acceptor Alternating π-Conjugated Polymers Containing Di(thiophen-2-yl)pyrene for Organic Thin Film Transistors
INTRODUCTION 15
EXPERIMENTAL SECTION 17
2.1. Materials 17
2.2. Synthesis 17
2.3. Characterization and Measurements 20
2.3.1. Instruments 20
2.3.2. Organic Thin Film Transistors (OTFTs) Fabrication 21
RESULTS AND DISCUSSION 23
2.4. Synthesis 23
2.5. Thermal Analysis of Pyrene-based Polymers 26
2.6. Optical Properties of Pyrene-based Polymers 28
2.7. Electron-State Distribution of Simplified Repeating Group and Geometry
of its Trimer Obtained by Molecular Mechanics Theoretical Calculation 30
2.8. Electrochemical Analysis of Pyrene-based Polymers 33
2.9. X-Ray Diffraction of Pyrene-based Polymers 36
2.10. Properties of OTFTs made from Pyrene-based Polymers 38
2.11. Surface Morphologies Observed by Atomic Force Microscope 42
2.12. Photoinduced Enhancement of Drain Current and Memory Application 44
CONCLUSION 47
REFERENCES 48
CHAPTER 3: A Tellurophene-containing π-Conjugated Polymer Derived from 2,5-Bis(2-octyldodecyl)-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione for High-Performance Thin Film Transistors
INTRODUCTION 52
EXPERIMENTAL SECTION 54
3.1. Materials 54
3.2. Synthesis 54
3.3. Characterization and Measurements 58
3.3.1. Instruments 58
3.3.2. Organic Thin Film Transistors (OTFTs) Fabrication 59
RESULTS AND DISCUSSION 60
3.4. Synthesis 60
3.5. Thermal analysis of PDTDPPT and PDTDPPTe 65
3.6. Optical Properties of PDTDPPT and PDTDPPTe 67
3.7. Electrochemical Properties of PDTDPPT and PDTDPPTe 70
3.8. X-ray Diffraction of PDTDPPT and PDTDPPTe 71
3.9. Device Performances of OTFTs based on PDTDPPT and PDTDPPTe 74
3.10. Morphology Study of PDTDPPT and PDTDPPTe 78
CONCLUSION 80
REFERENCES 81
ACKNOWLEDGMENTS 84
