2005 Fiscal Year Final Research Report Summary
Spin polarization enhanced molecular photoconductivity
| Project/Area Number |
15310069
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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 |
Nanostructural science
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| Research Institution | Tohoku University |
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Principal Investigator |
IKOMA Tadaaki Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Research Associate, 多元物質科学研究所, 助手 (10212804)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Photoinduced spin polarization / Giant magnetoconductivity / Radical pair mechanism / Excited triplet state / Quasi-one dimensional lattice / Molecular solid / Polyvinylcarbazole / Photocarrier |
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| Research Abstract |
Without any process using nanotechnology, molecule-based material has a potential for the exotic properties originated from the quantum effect happening in molecular level. However reports of this type of research have apparently not almost been published to date. Therefore, we have studied on magnetic field effect on photoconductivity of molecular film sample, in order to clarify the magnetoconductivity enhanced by photo induced spin polarization. The achievements of this research are summarized as following.
1) We found film samples in which the carrier yield was enhanced dramatically by generation from the excited triplet state of dopants. It was shown that the spin polarization and relaxation of electron-hole pair played an important role for the observed giant magnetoconductive effect.
2) In the experiment performed under strong magnetic field, the signals due to short distance electron hole pairs were detected for the first time. The observation confirms the stepwise hole hops in quasi-one dimensional lattice model.
3) Using magnetic field effect experiments, the spin dynamics in carrier generation for C60-doped polyvinylcarbazole film, which shows the highest photoconductivity, was clarified for the first time. The electron-hole pair created by excitation of charge transfer complex recombines to the local excited singlet state of C60 rather than the excited triplet state. The excited singlet state C60 relaxs to the ground state via the excited triplet state of C60.
The project succeeded to demonstrate the importance of spin polarization of carrier in conduction in molecular solid.
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Research Products
(30 results)
