2017 Fiscal Year Research-status Report
Novel Crystal Engineering Strategies for High Performance Semiconducting Thienoacenes
| Project/Area Number |
17K14478
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| Research Institution | Institute of Physical and Chemical Research |
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Principal Investigator |
WANG CHENGYUAN 国立研究開発法人理化学研究所, 創発物性科学研究センター, 特別研究員 (20772932)
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| Project Period (FY) |
2017-04-01 – 2019-03-31
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| Keywords | Alkylthionation / Thienoacenes / Packing / Molecular Orientation / OFETs |
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| Outline of Annual Research Achievements |
Based on my preliminary results and the proposed research plan, firstly, a straightforward chemistry to introduce alkylthio groups at the β-position of thienoacenes has been successfully developed. This chemistry utilizes disulfur dichloride as electrophilic reagent for cyclizaiton, which is reported firstly by this study.
Secondly, the model study of methylthionation of benzo[1,2-b:4,5-b’]dithiophene (BDT) to selectively tune the packing, molecular orientation and semiconducting properties has been completed. β-position methylthionation of BDT can change the packing of molecules into the rubrene-like "pitched" π-stacking and realize "edge-on" molecular orientation on the substrate. With these features β-methylthionated BDT shows more promising performance in single-crystal OFETs than its α-counterparts. This study suggests novel molecular designing strategy to develop high performance semiconducting materials.
Thirdly, thiacycle rings are used to modify BDT with S atoms at different positions and various ring size. This work emphasizes the importance of the position of S atoms in thiacycle rings and ring size in the functionalization of thienoacenes to tune their semiconducting properties.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Based on the research plan, I have achieved the two specific aims proposed in fiscal year 2017.
For the specific aim 1, the chemistry of β-position alkylthionation of thienoacenes can be applicable to various alkylthio groups. This chemistry gives moderate yield with mild conditions, with which we can successfully synthesize a series of target β-alkylthionated thienoacenes.
For the specific aim 2, the target four compounds can be successfully synthesized. The single crystals of the four molecules can be obtained, thus we can study the packing of the molecules. Through the thin-film transistor performance of the molecules, we can demonstrate how the crystal engineering to affect the semiconducting properties of molecules.
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| Strategy for Future Research Activity |
Based on the proposed research plan and my current research progress, in fiscal year 2018 I will focus on specific aim 3, which is the alkylthionation of larger π-conjugated thienoacenes, i.e., naphthodithiophenes(NDTs) and anthradithiophenes (ADTs).
The chemistry developed in fiscal year 2017 will be used to modify NDTs and ADTs. Alkylthio groups will be introduced to different positions i.e., α- and β-positions. Single crystals will be prepared to analyze the packing of the alkylthonated thienoacenes. X-ray diffraction measurement will be used to demonstrate the molecular orientation of the molecules on the substrates. Single-crystal based OFETs will be fabricated to investigate the semiconducting properties of the novel molecules.
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| Causes of Carryover |
In this fiscal year I will be focused on the specific aim 3, which is study of NDTs and ADTs. The starting materials to synthesize NDTs and ADTs are very expensive. In addition, I will purchase software to carry out theoretical calculation of transfer integrals of the crystals. These theoretical and experimental studies require more funding support. Thus, I need to transfer some money to this fiscal year to conduct the project, in order to make sure the project can be completed smoothly.
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