High thermoelectric performance in Cu-doped Bi2Te3 with carrier-type transition
Journal
Acta Materialia
Journal Volume
157
Start Page
33
End Page
41
ISSN
13596454
Date Issued
2018
Author(s)
Yen, Wan-Ting
Abstract
For decades, the Bismuth-telluride (Bi2Te3) has been intensively studied as the thermoelectric (TE) cooler. Still, new ideas and emerging results are put forward for raising the conversion efficiency. Herein, we re-visit the Cu-doped Bi2Te3, and report the high zT values nearing the room temperature, for both the p-type (Cu2Te)0.01(Bi2Te3)0.99/Cu0.01Bi1.99Te3 (zT∼1.2 at 300 K) as well as the n-type (Cu2Te)0.09(Bi2Te3)0.91 (zT∼1.09 at 363 K), respectively. Given that the phase boundary mapping is essential for the optimization of high-efficiency TE materials, the isothermal section of ternary Bi-Cu-Te at 523 K is constructed, by collecting the phase equilibria information of various thermally-equilibrated alloys; it further guides the alloying directions for (Cu2Te)x (Bi2Te3)1-x and CuyBi2-yTe3, respectively. Small modulation in the stoichiometry leads to the carrier type transition. As a consequence, the lamellae composed of Bi2Te3 and Cu7Te5 precipitate along the grain boundary of the n-type (Cu2Te)0.09(Bi2Te3)0.91, resulting in the reduced κ due to the stronger interfacial phonon scattering, and the higher PF, owing to the higher amounts of Te vacancy (VTe). On the contrary, the promising p-type (Cu2Te)0.01(Bi2Te3)0.99/Cu0.01Bi1.99Te3 features the single-phase Bi2Te3, whereas the soluble Cu introduces extra holes and might therefore promote the p-type conduction. © 2018 Acta Materialia Inc.
Subjects
Bi-Cu-Te
Bi2 Te3
Carrier type transition
Isothermal section
Thermoelectric (TE)
SDGs
Publisher
Acta Materialia Inc
Type
journal article