Abstract
The temperature-dependent electronic structures in the thermoelectric semiconductor CoSb3 and its Yb-filled counterpart are studied by using the electron-phonon renormalization (EPR) method, considering both lattice expansion and phonon-induced atomic vibrations. The primary direct band gaps at the Γ-point for skutterudites decrease with increasing temperature, largely due to the increase in the energy level at the valance band maximum (VBM). The energy difference between the conduction band minimum (CBM) and second CB also decreases with temperature, inducing band convergence at high temperatures. The phonon vibrations of the Sb rings are responsible for these temperature-dependent electronic structures. Specifically, the four Sb-ring-related Ag phonon mode in CoSb3 plays a decisive role in causing the increase in the VBM with temperature and decrease in the primary band gap. The band convergence at high temperatures is due to the different responses to lattice vibrations of the second CB and the CBM for both systems. Our work sheds light on the relation between chemical bonds and phonon-assisted electronic structures.
Original language | English (US) |
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Pages (from-to) | 1046-1052 |
Number of pages | 7 |
Journal | Chemistry of Materials |
Volume | 33 |
Issue number | 3 |
DOIs | |
State | Published - Feb 9 2021 |
Funding
This work was supported by the National Key Research and Development Program of China (nos. 2018YFB0703600 and 2017YFB0701600), the National Natural Science Foundation of China (grant nos. 21703136, 51632005, 51761135127, and 11674211), and the 111 Project D16002. W.Z. acknowledges the support from the Guangdong Innovation Research Team Project (no. 2017ZT07C062), Guangdong Provincial Key-Lab program (no. 2019B030301001), and Shenzhen Municipal Key-Lab program (ZDSYS20190902092905285). J.X. acknowledges the support from the Shanghai Sailing Program, China (17YF1427900). Part of the calculations were supported by the Center for Computational Science and Engineering at Southern University of Science and Technology. G.J.S. acknowledges NSF DMREF award no. 1729487.
ASJC Scopus subject areas
- General Chemistry
- General Chemical Engineering
- Materials Chemistry