High-performance Organic Field-Effect Transistors Based on Monodisperse Glassy-Nematic Oligofluorenes
| Project/Area Number |
16360011
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
TSUTSUI Tetsuo KYUSHU UNIVERSITY, Institute for Material Chemistry and Engineering, Professor, 総合理工学研究院, 教授 (40037982)
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| Co-Investigator(Kenkyū-buntansha) |
FUJITA Katsuhiko KYUSHU UNIVERSITY, Institute for Material Chemistry and Engineering, Associate Professor, 先導物質化学研究所, 助教授 (20281644)
KATAHIRA Yoshiko KYUSHU UNIVERSITY, Faculty of the Interdisciplinary Graduate School of Engineering Sciences, Research Associate, 大学院・総合理工学研究院, 助手 (90315143)
YASUDA Takeshi KYUSHU UNIVERSITY, Institute for Material Chemistry and Engineering, Research Associate, 先導物質化学研究所, 助手 (30380710)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥13,900,000 (Direct Cost: ¥13,900,000)
Fiscal Year 2005: ¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2004: ¥10,600,000 (Direct Cost: ¥10,600,000)
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| Keywords | organic semiconductor / transistor / liquid crystal / fluorene / 有機FET / オリゴマー / 移動度 / 有機トランジスタ / フルオレンオリゴマー / キャリア移動度 / ガラス薄膜 / キャリア注入 |
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| Research Abstract |
This study was motivated to identify factors affecting hole mobility in uniaxially oriented п-conjugated systems. In addition to the monodisperse oligofluorenes that have been reported recently, thermotropic liquid crystalline fluorene-thiophene oligomers were synthesized and characterized for hole mobility using field-effect transistors. Both series of monodisperse conjugated oligomers and their polymer analogues were prepared into glassy-amorphous, and polydomain and monodomain glassy-nematic films for a systematic study of the effects on hole mobility of chain length, molecular aggregation, orientational order parameter, and the contact resistance in a field-effect transistor.
Field-effect transistors were fabricated using hepta- and dodecafluorenes, F(Pr)5F(MB)2 and F(MB)10F(EH)2, and a polyfluorene. Hole mobilities were measured for devices comprising monodomain and polydomain glassy-nematic films as well as glassy-amorphous films. Oligofluorenes were more readily aligned into monodomain films via thermal annealing at a lower temperature, resulting in a higher R_<abs> than polyfluorene. Glassy-amorphous films possess the lowest mobility of all because of the geometric and energetic disorder. The mobility of a monodomain glassy-nematic F(MB)10F(EH)2 film is enhanced over a glassy-amorphous film by a factor of 800. In monodomain films, the field-effect mobility value is determined by the oligofluorene's chain length and the polyfluorene's persistence length. For F(MB)10F(EH)2, the field-effect mobility was evaluated at 0.012 cm^2/Vs with an on/off ratio of 1.0×10^4. This mobility value is twice that of polyfluorene in the same device structure. It is concluded that monodisperse glassy-nematic conjugated oligomers hold great potential for use in field-effect transistors because of superior chemical purity, structural uniformity and regularity, and ease of processing into uniaxially aligned defect-free films.
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Report
(3 results)
Research Products
(21 results)
