题目：Enhancing thermoelectric properties of low-dimensional materials

报告人 Nguyen Tuan Hung

单位：日本东北大学物理系

报告时间：12月6日（周三），上午10:00-12:00，

地点：李薰楼468室

Enhancing thermoelectric properties of low-dimensional materials

Nguyen T. Hung, Ahmad R. T. Nugraha, Riichiro Saito
Department of Physics, Tohoku University, Sendai 980-8578, Japan
Corresponding Author: Nguyen Tuan Hung
Tel: +81-22-795-6442, Fax: +81-22-795-6447,
E-mail: nguyen@flex.phys.tohoku.ac.jp

Thermoelectricity (TE) is the simplest technology applicable and environmentally friendly solution for direct heat-to-electricity energy conversion. Low-dimensional materials have been known to improve their TE performance by reducing confinement lengths of the materials, such as the diameter of nanowires or thickness of thin films, thanks to the seminal work of Hicks and Dresselhaus [1]. However, in some cases, reducing the confinement lengths does not immediately enhance the TE performance. For example, in silicon nanowires, the TE performance of the nanowires with diameters of about 30 nm still have similar performance with the bulk silicons [2]. To solve this problem, we showed that the TE performance of low-dimensional semiconductors depends not only on the confinement length, but also on the thermal de Broglie wave length [3]. The TE performance is enhanced in one-(1D) and two-dimensional (2D) semiconductors only when the confinement length is smaller than the thermal de Broglie wave length of the semiconductors. On the other hand, for 1D material such as semiconducting single wall carbon nanotubes (s-SWNTs) with diameters less than 0.6 nm might be more promising as a TE material due to the large Seebeck coefficient (~2000 μV/K) [4]. For 2D material, we found that high TE power factor in monolayer InSe originates from both the unique band structure and unusual shape of density of states of monolayer InSe by using the Boltzmann transport theory and first-principles calculations [5].

[1] L. D. Hicks and M. S. Dresselhaus, Phys. Rev. B 47, 12727 and 16631(R) (1993).
[2] A. I. Hochbaum et al., Nature 451, 163 (2008).
[3] N. T. Hung et al., Phys. Rev. Lett. 117, 036602 (2016).
[4] N. T. Hung et al., Phys. Rev. B. 92, 165426 (2015).
[5] N. T. Hung et al., Appl. Phys. Lett. 111, 092107 (2017).