2005 Fiscal Year Final Research Report Summary
Preparation and ultrafast carrier dynamics of semiconductor nanoparticles
| Project/Area Number |
15510098
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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 |
Nanomaterials/Nanobioscience
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| Research Institution | The University of Electro-Communications |
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Principal Investigator |
TOYODA Taro The University of Electro-Communications, Faculty of Electro-Communications, Professor, 電気通信学部, 教授 (40217576)
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| Co-Investigator(Kenkyū-buntansha) |
QING Shen The University of Electro-Communications, Faculty of Electro-Communications, Research Associate, 電気通信学部, 助手 (50282926)
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| Project Period (FY) |
2003 – 2005
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| Keywords | semiconductor nanoparticles / TiO_2 nanoparticles / ZnS nanoparticles / photovoltaic phenomena / luminescence properties / photoacoustic spectrum / photoelectrochemica spectrum / transient characterization |
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| Research Abstract |
Significant progress in solar cell application has been made since 1990's using nanostructured TiO_2 electrodes adsorbed with organic dyes (DSSC). In addition to organic dyes, semiconductor quantum dots (QDs) have also attracted much interest as light harvesters in DSSC. In this study, we prepared nanostructured TiO_2 electrodes with different morphologies. We adsorbed CdSe QDs onto the electrodes as photosensitizers. Characterization by photoacoustic (PA), photoelectrochemical current (PEC), and transient grating (TG) methods were applied. Redshoft of the PA spectrum with the increase of CdSe QDs adsorption time can be clearly observed and the PEC spectrum showed the photosensitization in the visible region resulting from the QDs adsorption. The decay time of excited electrons in the CdSe QDs was different with each nanostructured TiO_2 electrodes with different morphologies, reflecting the difference of crystal growth of CdSe QDs on each nanostructured TiO_2 electrodes.
Research involving Mn doped annocrystalline ZnS (ZnS : Mn) has grown in recent years, partly due to the high quantum luminescence efficiencies. We measured PA, photoluminescence (PL), and the PL excitation (PLE) spectra of surface-passivated and unpassivated ZnS : Mn. The effects of ultraviolet (UV) irradiation on the PL and PLE spectra were also studied. A decrease of PA intensity after UV exposure was observed for ZnS : Mn, indicating a decrease in the nonradiative relaxation probability. The observed increase in PL intensity indicates a corresponding increase in the radiative transition probability.
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