Investigation and control of thermal transport in low-dimensional organic single crystals

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K14525
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 29010:Applied physical properties-related
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Takehara Ryosuke 東京工業大学, 科学技術創成研究院, 助教 (00869779)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: 熱伝導度 / 熱拡散率 / 有機単結晶 / πスタック / 低次元系 / 異方性 / フォノン / 比熱

Outline of Final Research Achievements

In this study, we established thermal conductivity measurement methods, measured various thermophysical properties, and investigated thermal transport properties for organic single crystals, which have not been studied extensively so faar. The applicant targeted low-dimensional organic single crystals with π-stacked column structures. We revealed that acoustic phonons are formed and carry thermal energy in the π-stack direction, whereas no phonon formation was observed in the direction where only van der Waals forces act. In spite of the homogeneous arrangement of molecules in a single crystal, amorphous thermal conduction behavior was observed in this direction. It was also clarified that the thermal energy stored in intramolecular vibrations peculiar to organic materials is also carried by acoustic phonons through the couplings between intramolecular vibrational modes and acoustic phonons.

Free Research Field

物性物理

Academic Significance and Societal Importance of the Research Achievements

これまでに行われてきた有機物質における熱輸送研究は、汎用的な高分子結晶や、有機電荷移動錯体、また界面熱材料開発を目的として有機単層膜を対象に行われてきたが、無機物質に比べてその例は依然少ない。特に低分子量の有機単結晶の熱輸送研究例は少ない。しかし、有機導体、有機半導体の電気的、磁気的、光学的研究の歴史を振り返ると、これらは低分子量の単結晶を対象とした研究から始まり、大きな発展をとげた。このような背景を考えると、今回の有機単結晶を対象とした熱輸送研究により得られた知見は、基礎、応用も含め、今後の有機熱輸送研究の基盤となり得ると考えられる。