Structure-property relationship of various semiconductors under high pressure probed by electromagnetic wave

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K23651
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0502:Inorganic/coordination chemistry, analytical chemistry, inorganic materials chemistry, energy-related chemistry, and related fields
• Research Institution: Kyoto University
• Principal Investigator: Yusuke Tsutsui 京都大学, 工学研究科, 助教 (50845592)
• Project Period (FY): 2019-08-30 – 2021-03-31
• Keywords: 有機半導体 / 圧力 / 電気伝導度

Outline of Final Research Achievements

Since inter-molecular interaction is basically based on weak van der Waals force, the external pressure is expected to largely modulate the inter-molecular distance and electronic property of organic semiconductors. In this research, thienoacenes coated on a flexible substrate was pressurized by introducing the bending on substrate, and their conductivity was monitored by microwave conductivity.
Based on in-situ X-ray diffraction experiment, 0.8% modulation in their crystal lattice was induced by bending of the substrate. While band calculation afforded subtle modulation in its band structure, microwave conductivity has increased upon bending, suggesting the increase in relaxation time would be the origin rather than the decrease in the effective mass.

Free Research Field

有機材料化学

Academic Significance and Societal Importance of the Research Achievements

マイクロ波電気伝導度測定法は通常の接触式電気伝導度測定法よりも粒界の影響を受けにくく、成膜の最適化なしに材料の本質的な電気伝導度にアクセスが容易である。本研究により、フレキシブル基板を用いた圧力印加時の電気伝導度をマイクロ波でプローブする測定系を開発した。これまでフレキシブル基板を曲げたときの材料の電気特性はあまり研究がなされてこなかったが、これによりさまざまな有機半導体材料の電気特性を評価することが可能になると期待される。