Abstract
Bi2Si2Te6, a 2D compound, is a direct band gap semiconductor with an optical band gap of ∼0.25 eV, and is a promising thermoelectric material. Single-phase Bi2Si2Te6 is prepared by a scalable ball-milling and annealing process, and the highly densified polycrystalline samples are prepared by spark plasma sintering. Bi2Si2Te6 shows a p-type semiconductor transport behavior and exhibits an intrinsically low lattice thermal conductivity of ∼0.48 W m-1 K-1 (cross-plane) at 573 K. The first-principles density functional theory calculations indicate that such low lattice thermal conductivity is derived from the interactions between acoustic phonons and low-lying optical phonons, local vibrations of Bi, the low Debye temperature, and strong anharmonicity result from the unique 2D crystal structure and metavalent bonding of Bi2Si2Te6. The Bi2Si2Te6 exhibits an optimal figure of merit ZT of ∼0.51 at 623 K, which can be further enhanced by the substitution of Bi with Pb. Pb doping leads to a large increase in power factor S2σ, from ∼3.9 μW cm-1 K-2 of Bi2Si2Te6 to ∼8.0 μW cm-1 K-2 of Bi1.98Pb0.02Si2Te6 at 773 K, owing to the increase in carrier concentration. Moreover, Pb doping induces a further reduction in the lattice thermal conductivity to ∼0.38 W m-1 K-1 (cross-plane) at 623 K in Bi1.98Pb0.02Si2Te6, due to strengthened point defect (PbBi′) scattering. The simultaneous optimization of the power factor and lattice thermal conductivity achieves a peak ZT of ∼0.90 at 723 K and a high average ZT of ∼0.66 at 400-773 K in Bi1.98Pb0.02Si2Te6.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1445-1454 |
| Number of pages | 10 |
| Journal | Journal of the American Chemical Society |
| Volume | 144 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jan 26 2022 |
Funding
This work was supported in part the Department of Energy, Office of Science Basic Energy Sciences under grant DE-SC0014520, DOE Office of Science (materials synthesis, TE characterization, TEM, DFT) and in part by the National Natural Science Foundation of China (Grant Nos. 52002137, 92163211, 51802070, and 51632006). This work made use of the EPIC facilities of Northwestern’s NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. User Facilities are supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-06CH11357 and DE-AC02-05CH11231. Access to facilities of high-performance computational resources at the Northwestern University is acknowledged. The authors also acknowledge Singapore MOE AcRF Tier 2 under Grant Nos. 2018-T2-1-010, Singapore A*STAR Pharos Program SERC 1527200022, Singapore A*STAR project A19D9a0096, the Fundamental Research Funds for the Central Universities under Grant No. 2021XXJS008 and 2018KFYXKJC002. We gratefully acknowledge the technical assistance from the Analytical and Testing Center of HUST. This work was supported in part the Department of Energy Office of Science Basic Energy Sciences under grant DE-SC0014520 DOE Office of Science (materials synthesis, TE characterization, TEM DFT) and in part by the National Natural Science Foundation of China (Grant Nos. 52002137, 92163211, 51802070, and 51632006). This work made use of the EPIC facilities of Northwestern’s NUANCE Center which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. User Facilities are supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-06CH11357 and DE-AC02-05CH11231. Access to facilities of high-performance computational resources at the Northwestern University is acknowledged. The authors also acknowledge Singapore MOE AcRF Tier 2 under Grant Nos. 2018-T2-1-010, Singapore A*STAR Pharos Program SERC 1527200022, Singapore A*STAR project A19D9a0096, the Fundamental Research Funds for the Central Universities under Grant No. 2021XXJS008 and 2018KFYXKJC002. We gratefully acknowledge the technical assistance from the Analytical and Testing Center of HUST.
ASJC Scopus subject areas
- General Chemistry
- Biochemistry
- Catalysis
- Colloid and Surface Chemistry