The Synthesis of Dithienothiophene (DTT) Derivatives for Organic Thin Film Transistors
- Abstract
- In chapter 2,
Newly synthesized solution-processable dithieno[3,2-b:2’,3’-d]thiophene (DTT) based asymmetric compounds, such as 2-octyldithieno[3,2-b:2’,3’-d]thiophene (5), 2-octyl-6-(thiophen-2-yl)dithieno[3,2-b:2',3'-d]thiophene (6), 2-octyl-6-(5-octylthiophen-2-yl)dithieno[3,2-b:2’,3’-d]thiophene (7) and 2-(5-(2-ethylhexyl)thiophen-2-yl)-6-octyldithieno[3,2-b:2’,3’-d]thiophene (8) were fabricated as small molecular organic semi-conductors for top-contact/bottom-gate organic thin-film transistors (OTFTs). Physicochemi-cal properties of four compounds were investigated, and the tendencies such as melting tem-perature, maximum absorption wavelength, HOMO/LUMO energy level and band gap showed fine accordance with structural analyses of DTT core group, alkylated thiophene group and alkyl side chains. Developed OTFTs exhibited clear p-channel characteristics, and especially compound 6 with additional thiophene group and linear alkyl chain (octyl group) performed superior electrical performance with hole mobility over 0.07 cm2V-1s-1 and current on/off ratio > 108 in ambient environment. Moreover, film microstructure and morphology were analyzed via atomic force microscopy (AFM) and θ-2θ X-ray diffraction (XRD), corre-lating with corresponding electrical performance. In particular, high device performance of compound 6 could be supported by distinct, high peak intensity of XRD data and terrace-like layered morphology of thin films.
In chapter 3,
Solution-processable dithieno[3,2-b:2′,3′-d]thiophene (DTT) derivatives, 2-octyl-6-(phenylethynyl)dithieno[3,2-b:2',3'-d]thiophene (9), (E)-2-octyl-6-styryldithieno[3,2-b:2',3'-d]thiophene (10), 2-octyl-6-(thiophen-2-ylethynyl)dithieno[3,2-b:2',3'-d]thiophene (11) and (E)-2-octyl-6-(2-(thiophen-2-yl)vinyl)dithieno[3,2-b:2',3'-d]thiophene (12) were synthesized and characterized as organic semiconductors for organic thin-film transistors (OTFTs). Ther-mal, optical, and electrochemical properties of the DTT-based semiconductors were investi-gated. The organic thin film transistors based on DTT derivatives exhibited p-channel charac-teristics as an active layer in organic thin-film transistors. In particular, compound 9 with phenylacetylene group has the highly performance and electron mobility of 0.022 cm2V-1s-1 and a current on/off ratio of >106.
In chapter 1,
Solution-processable dithieno[3,2-d:2’,3’-d]thiophene (DTT) derivatives with alkylated thiophene or alkyl chain substituents, 2,6-bis(5-octylthiophen-2-yl)dithieno[3,2-b:2’,3’-d] thiophene (1), 2,6-bis(5-(2-ethylhexyl)thiophen-2-yl)dithieno[3,2-b:2’,3’-d]thiophene (2) and 2,6-dioctyldithieno[3,2-b:2’,3’-d]thiophene (3), have been synthesized and employed as small molecular organic semiconductors for organic field-effect transistors (OFETs). All compounds exhibited good thermal stability over 290 ℃, while different side groups of DTT compounds afforded different melting temperatures. In particular, the DTT derivative with an alkyl chain (octyl) substituent showed the best performance and a maximum electron mobility of 0.10 cm2V-1s-1 and a current on/off ratio of >107.
- Issued Date
- 2022
- Awarded Date
- 2022. 2
- Type
- Dissertation
- Keyword
- OTFT
- Publisher
- 부경대학교
- Affiliation
- 부경대학교 대학원
- Department
- 대학원 스마트그린기술융합공학과
- Advisor
- 서성용
- Table Of Contents
- Chapter 1. Development of Dithieno[3,2-b:2’,3’-d]thiophene (DTT) Derivatives as Solution-Processable Small Molecular Semiconductors for Organic Thin Film Transistors 1
1.1 Introduction 1
1.2 Experimental 5
1.2.1 General Materials and Methods 5
1.2.2 Synthesis 6
1.2.2.1 Synthesis of dithieno[3,2-b:2’,3’-d]thiophene (4) 8
1.2.2.2 Synthesis of 2,6-Diiododithieno[3,2-b:2’,3’-d]thiophene (4a) 8
1.2.2.3 Synthesis of 2,6-Dioctyldithieno[3,2-b:2’,3’-d]thiophene (1) 8
1.2.2.4 Synthesis of 2,6-Bis(5-octylthiophen-2-yl)dithieno[3,2-b:2’,3’-d]thiophene (2) 9
1.2.2.5 Synthesis of 2,6-Bis(5-(2-ethylhexyl)thiophen-2-yl)dithieno[3,2-b:2’,3’-d]thiophene (3) 9
1.2.3 Theoretical Calculation 10
1.2.4 Device Fabrication 10
1.2.5 Device Characterization 11
1.3 Results and discussion 12
1.3.1 Thermal, Optical, and Electrochemical Properties 12
1.3.2 Theoretical Calculation 19
1.3.3 Thin-Film Transistor Characterization 21
1.3.4 Thin-Film Microstructure and Morphology 25
1.4 Conclusions 29
Chapter 2. Asymmetric Dithieno[3,2-b:2’,3’-d]thiophene (DTT) Derivatives as Solution-Processable Small Molecular Organic Semiconductors for Organic Thin Film Transistors 30
2.1 Introduction 30
2.2 Experimental 36
2.2.1 General Methods 36
2.2.2 Synthesis 37
2.2.2.1 Synthesis of dithieno[3,2-b:2’,3’-d]thiophene (4) 37
2.2.2.2 Synthesis of 2-octyldithieno[3,2-b:2’,3’-d]thiophene (5) 37
2.2.2.3 Synthesis of 2-iodo-6-octyldithieno[3,2-b:2',3'-d]thiophene (5a) 38
2.2.2.4 Synthesis of 2-octyl-6-(thiophen-2-yl)dithieno[3,2-b:2',3'-d]thiophene (6) 38
2.2.2.5 Synthesis of 2-octyl-6-(5-octylthiophen-2-yl)dithieno[3,2-b:2’,3’-d]thiophene (7) 39
2.2.2.6 Synthesis of 2-(5-(2-ethylhexyl)thiophen-2-yl)-6-octyldithieno[3,2-b:2’,3’-d]thiophene (8) 39
2.2.3 Theoretical Calculation 40
2.2.4 Device Fabrication and characterization 40
2.3. Results and discussion 42
2.3.1 Synthesis 42
2.3.2 Thermal and optical properties 44
2.3.3 Electrochemical properties 50
2.3.4 Theoretical calculation 52
2.3.5 Thin film transistor characterization 54
2.3.6 Thin-film microstructure and morphology 58
2.4 Conclusions 62
Chapter 3. Dithieno[3,2-b:2’,3’-d]thiophene (DTT) Derivatives with Alkyne or Alkene Functional Groups as Solution-Processable Organic Semiconductors for Organic Thin Film Transistors 63
3.1 Introduction 63
3.2 Experimental 68
3.2.1 General Materials and Methods 68
3.2.2 Synthesis 69
3.2.2.1 Synthesis of 2-octyl-6-(phenylethynyl)dithieno[3,2-b:2',3'-d]thiophene (9) 69
3.2.2.2 Synthesis of (E)-2-octyl-6-styryldithieno[3,2-b:2',3'-d]-thiophene (10) 69
3.2.2.3 Synthesis of 2-octyl-6-(thiophen-2-ylethynyl)dithieno[3,2-b:2',3'-d]thiophene (11) 70
3.2.2.4 Synthesis of trimethyl((6-octyldithieno[3,2-b:2',3'-d]thiophen-2-yl)ethynyl)silane (11a) 71
3.2.2.5 Synthesis of 2-ethynyl-6-octyldithieno[3,2-b:2',3'-d]thiophene (11b) 71
3.2.2.6 Synthesis of (E)-2-octyl-6-(2-(thiophen-2-yl)vinyl)dithieno[3,2-b:2',3'-d]thiophene (12) 72
3.2.3 Theoretical Calculation 72
3.2.4 Device Fabrication 73
3.2.5 Device Characterization 73
3.3 Results and discussion 75
3.3.1 Synthesis 75
3.3.2 Thermal, Optical, and Electrochemical Properties 77
3.3.3 Theoretical Calculation 84
3.3.4 Thin-Film Transistor Characterization 86
3.4 Conclusions 89
References 88
APPENDIX 104
- Degree
- Master
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