2018 Fiscal Year Final Research Report
Development of STM-based Helium-free spectroscopy and measurements for electronic states of organic semiconductors
| Project/Area Number |
16K05656
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | Osaka University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | 表面 / 走査トンネル顕微鏡 / 有機半導体 / 非占有準位 / 2光子光電子分光 |
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| Outline of Final Research Achievements |
The electronic states of the organic semiconductor on the solid surface are a mixture of the electronic states of the individual molecules and the contribution from the molecules aggregated by intermolecular interaction.Therefore, it is important to assess the electronic state by evaluating the adsorption state and the electronic structure from the single molecule level. In this study, we have established a method to measure the electronic state of ultrathin films using scanning tunneling microscopy (STM) under the conditions that do not require the use of liquid helium. Localization and delocalization of molecular orbitals are important factors in considering charge transport in organic devices. By combining macroscopic measurements with two-photon photoemission (2PPE) spectroscopy, we have found it possible to obtain microscopic picture of unoccupied levels at the nanoscale.
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| Free Research Field |
表面化学
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| Academic Significance and Societal Importance of the Research Achievements |
物質の温度を極低温に下げ,熱に由来する様々なノイズを低減した条件下における物性計測が広く行われている。これらの実験では液体ヘリウム(約4 K,-269℃)を寒剤として用いられており，表面科学分野においては,走査トンネル顕微鏡(STM)を用いたSTM単一分子分光が盛んに行われている。基礎科学分野において,液体ヘリウムの使用が大前提となっている計測手法の代替案を探索することが本研究テーマの一つである。本研究では，液体ヘリウムを使わない局所分光法・電子状態マッピング法を展開し，有機半導体分子膜に適用することで，単一分子レベルで表面電子状態を評価することができた。
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