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2022 Fiscal Year Final Research Report

Design for thermoelectric properties measurement of single molecule junctions

Research Project

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Project/Area Number 18H03899
Research Category

Grant-in-Aid for Scientific Research (A)

Allocation TypeSingle-year Grants
Section一般
Review Section Medium-sized Section 32:Physical chemistry, functional solid state chemistry, and related fields
Research InstitutionOsaka University

Principal Investigator

Tada Hirokazu  大阪大学, 大学院基礎工学研究科, 教授 (40216974)

Co-Investigator(Kenkyū-buntansha) 山田 亮  大阪大学, 大学院基礎工学研究科, 准教授 (20343741)
大戸 達彦  大阪大学, 大学院基礎工学研究科, 助教 (90717761)
Project Period (FY) 2018-04-01 – 2022-03-31
Keywordsナノ接合 / 単一分子接合 / 熱電変換 / 熱伝導度 / ゼーベック係数
Outline of Final Research Achievements

We established a method to accurately measure the electrical conductivity, Seebeck coefficient, and thermal conductivity of structurally well-defined metal and single-molecule junctions, enabling us to investigate the heat transport mechanism in nanomaterials. To minimize heat dissipation, we fabricated suspended devices on SiN using nanolithography techniques. The electrodes were created via the electromigration method, and an actuator driven by thermal expansion was incorporated to control the gap spacing. The Seebeck coefficient of the metal wire showed excellent agreement with the theoretical formula, and quantization was confirmed for wires with diameters below 10 nm. The temperature dependence of thermal conductivity also aligned well with theoretical calculations. Furthermore, we successfully measured the gap spacing dependence of thermal conductivity and found that the near-field effect dominated when the gap was less than 2 nm.

Free Research Field

分子エレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

エネルギー問題の解決のひとつとして、廃熱を電気エネルギーに変換する熱電変換技術に期待が寄せられている。実用化に向けてはバルク材料を用いた開発研究が活発化しているが、ナノレベルの熱の輸送機構の解明は学術的にも重要である。ナノ技術の進展により、単一分子やナノ物質の物性計測が可能となっているが、熱の輸送機構の計測は散逸を防ぐ必要があるため、精度のよい計測が難しい。今回開発した宙吊り構造の素子は、アクチェーターによって電極が動き、細線の太さや真空ギャップ間隔を制御しながら、電気伝導度と熱伝導度を同時計測することを可能とし、ナノ材料の熱輸送に関する理解が深まると思われる。

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Published: 2024-01-30   Modified: 2025-03-27  

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