2000 Fiscal Year Final Research Report Summary
An attempt to build high-mobility π-conjugated molecular materials
| Project/Area Number |
10650809
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
工業物理化学
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
HARIMA Yutaka Faculty of Integrated Arts & Sciences, HIROSHIMA UNIVERSITY, Professor, 総合科学部, 教授 (20156524)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Functionnality materials / conduction mechanism / mobility / polaron / π-dimer / bipolaron / conducting polymer |
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| Research Abstract |
A novel electrochemical technique was established to evaluate apparent mobilities of charge carriers in conducting polymers in a range of doping levels. Using the electrochemical doping enabled us to correlate the mobility change with the change of the natures of charged species induced by doping and eventually to better understand the switching of the conduction mechanism at increased doping levels. For example, mobilities of poly (3-methylthiophene)(PMT) film were successfully measured over a wide range of doping levels. The mobility was found to increase by four orders of magnitude by doping. In contrast, mobilities in a poly [(ethoxypropylsilanylene)-quinque (2,5-thienylene)](MS5T-OEt) decreased monotonously with the increase in doping level up to a few percents, in contrast to four order-of-magnitude increase of mobilities for the PMT film. This clear difference indicates that the two kinds of diamagnetic species, cation radical π-dimers in the MS5T-OEt film and bipolarons in the PMT film, are related to the electrical conduction in completely different manners. A rather small difference between mobilities in almost dedoped MS5T-OEt and PMT films is discussed from a viewpoint of an interchain or intrachain transport of polarons. An in situ ESR study performed to characterize charge-carrying species in the MS5T-OEt film demonstrates that there are oligothienylene segments where polarons are isolated so as not to form π-dimers. This mobility study was extended to some other Si copolymers to further clarify conduction mechanisms of common doncucting polymers.
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[Publications] J.Ohshita, A.Takata, H.Kai, A.Kunai, K.Komaguchi, M.Shiotani, A.Adachi, K.Sakamaki, K.Okita, Y.Harima, Y.Kunugi, K.Yamashita, and M.Ishikawa: "Synthesis of polymers with alternating organosilanylene and oligothienylene units and their optical, conducting, and hole-transporting properties"Orgnometal.. 19. 4492-4498 (2000)
Description
「研究成果報告書概要(欧文)」より
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