Toward high efficiency thermoelectric material operating at low temperatures Extremely high electron mobility in a layered material with a silver nanosheet

Associate Prof. Shintaro Ishiwata and Prof. Yoshinori Tokura’s group at the University of Tokyo’s Graduate School of Engineering and researchers at the RIKEN Center for Emergent Matter Science have discovered that a layered material β-CuAgSe is promising for high-efficiency thermoelectrics operating at around room temperature.

© Shintaro Ishiwata. Red and purple spheres at the lattice points represent copper and selenium, respectively. This is an image illustrating the conduction electrons moving in the silver layer sandwiched by the copper-selenium layers at high speed, from the hot area in the rear to the cold area in the front.

Thermoelectric materials can be utilized not only as thermoelectric power generation modules but also as Peltier cooling devices. Although the Peltier cooler has various advantages such as potential for miniaturization, the cooling power is much lower than the conventional compressor-type cooler. Therefore, researchers have been searching for new thermoelectric materials with higher performance. The research group has found that a layered material β-CuAgSe with a partial substitution for Cu shows high thermoelectric performance, comparable to that of bismuth-based compounds from below room temperature down to -200℃. Based on transport measurements and first-principles calculations, the origin of the high thermoelectric performance was ascribed to the extremely high mobility electrons in the silver layers. The present study has provided a guiding principle for exploration of new thermoelectric materials for high-efficiency Peltier cooling devices.

Press release [pdf] (Japanese)

Paper

S. Ishiwata, Y. Shiomi, J. S. Lee, M. S. Bahramy, T. Suzuki, M. Uchida, R. Arita, Y. Taguchi, Y. Tokura,
“Extremely high electron mobility in a phonon-glass semimetal”,
Nature Materials Online Edition: 2013/4/22 (Japan time), doi: 10.1038/NMAT3621.
Article link

Links

Graduate School of Engineering

Department of Applied Physics, Graduate School of Engineering

Ishiwata Lab., Department of Applied Physics, Graduate School of Engineering (Japanese)

Tokura Lab., Department of Applied Physics, Graduate School of Engineering