Release from trade-off between Seebeck coefficient and electrical conducitivity by hybrid thermoelectric structures with dielectric materials

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04000
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: National Institute for Materials Science
• Principal Investigator: SHINOHARA Yoshikazu 国立研究開発法人物質・材料研究機構, エネルギー・環境材料研究拠点, 副拠点長 (70343853)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 熱電材料 / ハイブリッド / 出力因子

Outline of Final Research Achievements

Thermoelectric power generation is dominated by the electric structure of thermoelectric materials. Since Seebeck coefficient and electrical conductivity are in a trade-off relation, it is difficult to control both the properties separately. In this study, the multi-layered hybrid films consisting of a high-conductivity & low-Seebeck material and low-conductivity & high-Seebeck material were prepared by sputtering method, and the effect of the hybrid structure on thermoelectric power factor was investigated. The electrical conductivity of the hybrid film was more than that of the consisting materials at a thickness ratio of a high-conductivity & low-Seebeck layer was small, resulting in an improved power factor. The hybrid bulk material was also synthesized from thermoelectric material powders and metal nano-powders using hot pressing. The mixing ratio of metal powers was ~3%. It was found that the power factor was improved by up to 90% by hybridization.

Free Research Field

熱電材料

Academic Significance and Societal Importance of the Research Achievements

ゼーベック係数と電気伝導率はトレードオフの関係にあり、ゼーベック係数と電気伝導率を独立に制御して、出力因子を向上させることはできない。これは材料中で同じキャリア（ｎ型では電子、ｐ型では正孔）が熱輸送と電荷輸送の両方を担っていることが原因である。本研究では、材料内部に熱流経路と電荷流経路を造り分けて機能分担させることにより、出力因子を向上されることが可能であることを見出した。