Indexed by:期刊论文
Date of Publication:2018-08-21
Journal:JOURNAL OF MATERIALS CHEMISTRY C
Included Journals:SCIE
Volume:6
Issue:31
Page Number:8479-8487
ISSN No.:2050-7526
Abstract:Herein, we propose for the first time a novel recipe to improve the thermoelectric properties of BiCuSeO by doping with variable valence elements. Taking Yb-doped BiCuSeO as a typical example, the dimensionless figure of merit (ZT) is optimized by simultaneously doping with Yb2+ to increase the carrier concentration and by introducing Yb3+ to increase the carrier mobility. The mechanisms of valence fluctuation, the increase in carrier concentration and the increase in mobility are investigated by combining experimental results with first-principles calculations. By coupling high electronic conductivity, medium Seebeck coefficient, and low thermal conductivity, a maximum ZT value of 0.62 is achieved at 823 K for Bi0.7Yb0.3CuSeO, which is 1.55 times higher than that of pristine BiCuSeO. These findings undoubtedly provide a new strategy for the rational design of high-ZT thermoelectric materials.