Abstract
Although Ga doping can weaken the electron phonon coupling in n-type PbTe, Ga-doped PbTe has a relatively low carrier concentration (n) and high lattice thermal conductivity (κlat), resulting in a lower figure of merit (ZT) compared with those of other top-performing n-type PbTe-based thermoelectric materials. Herein, we report the extraordinary role of Zn in enhancing the thermoelectric performance of Ga-doped PbTe. It is discovered that Zn can simultaneously improve the electronic transport properties and decrease the κlat of Ga-doped PbTe, thereby affording a record high ZTavg ∼ 1.26 at 400-873 K, with a maximum ZT value of 1.55 at 723 K. The isoelectronic substitution of Zn for Pb in Ga-doped PbTe increases the electrical conductivity and n by inducing the nucleation and growth of Ga2Te3 in the second phase. The formation of Ga2Te3 results in nonstoichiometry and Te deficiency in the PbTe matrix, which increases the number of electron carriers. Additionally, discordant Zn and Ga atoms with displacing off-center from the ideal octahedral positions, as well as Ga2Te3 nanocrystals ranging from 30 to 200 nm coherently embedded into the PbTe matrix effectively weaken the phonon modes and scatter heat-carrying phonons, resulting in a significant reduction in κlat.
Original language | English (US) |
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Pages (from-to) | 368-375 |
Number of pages | 8 |
Journal | Energy and Environmental Science |
Volume | 15 |
Issue number | 1 |
DOIs | |
State | Published - Jan 2022 |
Funding
This study was supported primarily by the Department of Energy, Office of Science Basic Energy Sciences under grant DE-SC0014520, DOE Office of Science (sample preparation, synthesis, XRD, TE measurements, TEM measurements, DFT calculations), and Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China (2021ZZ127). The authors acknowledge the Minjiang Scholar Professorship (GXRC-21004) and the National Natural Science Foundation of China (61728401). The authors acknowledge the EPIC facility of Northwestern University’s NUANCE Center, which received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center, International Institute for Nanotechnology (IIN), Keck Foundation, State of Illinois, through the IIN; and the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-06CH11357 and DE-AC02-05CH11231. Access to facilities for high-performance computational resources at the Northwestern University is acknowledged. The authors acknowledge Singapore MOE AcRF Tier 2 under Grant No. 2018-T2-1-010, Singapore A*STAR project A19D9a0096, and the support from FACTs of Nanyang Technological University for sample analysis.
ASJC Scopus subject areas
- Environmental Chemistry
- Renewable Energy, Sustainability and the Environment
- Nuclear Energy and Engineering
- Pollution