2022 Fiscal Year Research-status Report
Development of a Simple and Scalable Method for Organic Semiconductor Single Crystal Growth and Formation of Multi-Single Crystal Thin Films for Applications in Field-Effect Transistor-Based Devices.
Project/Area Number |
22K14293
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Research Institution | Institute of Physical and Chemical Research |
Principal Investigator |
Bulgarevich Kirill 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 (60880268)
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Project Period (FY) |
2022-04-01 – 2024-03-31
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Keywords | 有機トランジスタ / 単結晶有機半導体 / 大気圧下蒸着 / 多単結晶膜 |
Outline of Annual Research Achievements |
A novel method for single-crystal (SC) growth, called "indirect sublimation," was successfully used to grow crystals of 1,3,6,8-tetrakis(methylthio)pyrene (MT-pyrene), MS-pyrene, rubrene, DNTT, and pentacene. High-coverage uniform crystals were obtained for MT- and MS-pyrene, which were transferred to a substrate using a rubbing machine to create a high-coverage multi-SC (MSC) film for device applications. MSC film-based organic field-effect transistors (OFETs) using MT-pyrene showed good on/off characteristics and high carrier mobilities (>20 cm2 V-1 s-1), comparable to SC devices (30 cm2 V-1 s-1). The development of novel high-mobility organic semiconductor materials was also performed, with a focus on designing molecules with brickwork crystal structures similar to MT-pyrene. A simulation algorithm was developed to accurately predict known brickwork-related crystal structures (MT- and MS-pyrene), and it was applied to the design of 1,3,8,10-tetrakis(methylthio)peropyrene (MT-peropyrene), which was synthesized and evaluated. SC-OFETs made with MT-peropyrene showed very high mobilities (30 cm2 V-1 s-1). Further optimization of the indirect sublimation method for MT-peropyrene and other materials, as well as fabrication of OFET-based devices such as pseudo-CMOS inverters, is ongoing. Additionally, novel material screening and development are being performed.
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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
The usefulness of "indirect sublimation" method and the good device performance of multi-single-crystal (MSC) films were confirmed. The rubbing machine for MSC film formation was fabricated and and was confirmed to be useful. It was also confirmed that individual single-crystal (SC) field-effect transistors (FETs) of MT-pyrene can be wired to produce a functioning pseudo-CMOS inverters that functioned with gain of over 30 at 5 V. The electrode pattern for fabricating the pseudo-CMOS inverters using MSC films was designed and is currently tested. Application of the above techniques to other materials as well as development of novel materials for SC device applications is undergoing.
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Strategy for Future Research Activity |
According to the research plan, in the second year the focus will be made on device applications of multi-single-crystal (MSC) films. Devices such as pseudo-CMOS inverters, logic gates, and RF-ID tags will be fabricated. The material choice, device architecture, and fabrication conditions will be optimized to achieve the best performance.
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Causes of Carryover |
The research proposed the development of a mechanical device for transferring single-crystal (SC) and introduction of a rubbing machine. Additionally, there was a need for costly expendable glassware to purify new organic semiconductor compounds through sublimation. These expenses were substantially cut by simplifying the transfer process, creating a homemade rubbing machine, and using less expensive glassware alternatives. The funds saved from this will be allocated to acquiring a two-channel source measuring unit to complement the existing four-channel system for enhanced device evaluation.
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Research Products
(7 results)