Peierls distortion as a route to high thermoelectric performance in In(4)Se(3-delta) crystals.
Thermoelectric energy harvesting-the transformation of waste heat into useful electricity-is of great interest for energy sustainability. The main obstacle is the low thermoelectric efficiency of materials for converting heat to electricity, quantified by the thermoelectric figure of merit, ZT. The best available n-type materials for use in mid-temperature (500-900 K) thermoelectric generators have a relatively low ZT of 1 or less, and so there is much interest in finding avenues for increasing this figure of merit. Here we report a binary crystalline n-type material, In(4)Se(3-delta), which achieves the ZT value of 1.48 at 705 K-very high for a bulk material. Using high-resolution transmission electron microscopy, electron diffraction, and first-principles calculations, we demonstrate that this material supports a charge density wave instability which is responsible for the large anisotropy observed in the electric and thermal transport. The high ZT value is the result of the high Seebeck coefficient and the low thermal conductivity in the plane of the charge density wave. Our results suggest a new direction in the search for high-performance thermoelectric materials, exploiting intrinsic nanostructural bulk properties induced by charge density waves.
Rhyee
Jong-Soo
JS
Materials Research Laboratory, Samsung Advanced Institute of Technology, Yongin 446-712, Korea.
Lee
Kyu Hyoung
KH
Lee
Sang Mock
SM
Cho
Eunseog
E
Kim
Sang Il
SI
Lee
Eunsung
E
Kwon
Yong Seung
YS
Shim
Ji Hoon
JH
Kotliar
Gabriel
G