| 研究開始時の研究の概要 |
The proposed research aims to develop a simple, scalable, and vacuum and solution free method for growth and transfer of organic semiconductor single crystals (SCs) for applications in high-performance devices based on organic field-effect transistors (OFETs). A method is proposed to cover entire substrate surface with SCs as Multi-SC films. Such films may have similar applications in OFET-based devices as solution grown thin-films, but can show better performance. Thus, practical applications will be offered to organic semiconductor SCs which are mainly used for studying intrinsic properties.
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| 研究実績の概要 |
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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| 今後の研究の推進方策 |
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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