Improvement of thermoelectric properties by use of impurity states, and development of new high-performance thermoelectric materials

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H01695
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26010:Metallic material properties-related
• Research Institution: Toyota Technological Institute
• Principal Investigator: Takeuchi Tsunehiro 豊田工業大学, 工学(系)研究科(研究院), 教授 (00293655)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 熱電材料 / 熱電発電 / ゼーベック係数 / 電気伝導度 / 熱伝導度 / 電子構造 / 不純物準位 / 強散乱極限

Outline of Final Research Achievements

In this project, we tried to improve the performance of thermoelectric materials using the impurity states produced by dilute impurity elements under the condition of strongest scattering limit of conduction electrons.
We employed Si-Ge system as one of the typical thermoelectric materials, and found that 1 at.% Fe possesses a potential to greatly increase the magnitude of dimensionless figure of merit of n-type samples. Tiny amount of Au and Ni, which is less than a few at.%, were also found to improve thermoelectric performance of p-type Si-Ge.The strategy, with which we successfully improve the thermoelectric performance of Si-Ge, was also used for other thermoelectric materials, such as silver chalcogenides, and its validity was confirmed by the increase of their dimensionless figure of merit.
We stress here that the our newly proposed strategy to develop a high-performance thermoelectric materials should lead to the practical use of thermoelectric generators.

Free Research Field

固体物性，金属電子論

Academic Significance and Societal Importance of the Research Achievements

本研究では，熱電材料の物性を建設的に制御する指針を与えるとともに，実際に，複数の材料系で，新しい高性能熱電材料の開発に至った．理論的な予測を実験で検証することで，提案する指針が正しいことを証明したことから，同様の指針を用いた熱電材料の開発が促されると考えられる．また，この指針を用いた材料開発が活発に行われることで，エネルギー変換効率が高い熱電発電素子の開発が行われるようになり，排熱からの熱電発電により省エネルギー化が進む．同時に，カーボンニュートラルの実現に向けて，大きな寄与をすると判断される．