Abstract
The presence of high crystallographic symmetry and nanoscale defects are favorable for thermoelectrics. With proper electronic structures, a highly symmetric crystal tends to possess multiple carrier channels and promote electrical conductivity without sacrificing Seebeck coefficient. In addition, nanoscale defects can effectively scatter acoustic phonons to suppress thermal conductivity. Here, it is reported that the triple doping of Cu2SnSe3 leads to a high ZT value of 1.6 at 823 K for Cu1.85Ag0.15(Sn0.88Ga0.1Na0.02)Se3, and a decent average ZT (ZTave) value of 0.7 is also achieved for Cu1.85Ag0.15(Sn0.93Mg0.06Na0.01)Se3 from 475 to 823 K. This study reveals: 1) Ag doping on Cu sites generates numerous point defects and greatly decreases lattice thermal conductivity. 2) Doping Mg or Ga converts the monoclinic Cu2SnSe3 into a cubic structure. This symmetry enhancing leads to an increase in the effective mass from 0.8 me to 2.6 me (me, free electron mass) and the power factor from 4.3 µW cm−1 K−2 for Cu2SnSe3 to 11.6 µW cm−1 K−2. 3) Na doping creates dense dislocation arrays and nanoprecipitates, which strengthens the phonon scattering. 4) Pair distribution function analysis shows localized symmetry breakdown in the cubic Cu1.85Ag0.15(Sn0.88Ga0.1Na0.02)Se3. This work provides a standpoint to design promising thermoelectric materials by synergistically manipulating crystal symmetry and nanoscale defects.
| Original language | English (US) |
|---|---|
| Article number | 2100661 |
| Journal | Advanced Energy Materials |
| Volume | 11 |
| Issue number | 42 |
| DOIs | |
| State | Published - Nov 11 2021 |
Funding
This work was supported by the U.S. Department of Energy, Office of Science Basic Energy Sciences under grant DE-SC0014520, DOE Office of Science (materials characterization, sample synthesis, transport properties). User Facilities were supported by the Office of Science of the U.S. Department of Energy under Contract Nos. 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 Tier 2 under Grant Nos. MOE2018-T2-1-010, Singapore A*STAR Pharos Program SERC 1527200022, and Singapore A*STAR project A19D9a0096. The electron microscopy and XRD work were performed at the Facility for Analysis, Characterization, Testing and Simulation (FACTS), Nanyang Technological University, Singapore. The synchrotron radiation experiments were performed at the BL02B2 of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2021A1074). Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Science, under Contract DE-AC02-06CH11357. Y.-W.F. acknowledges the computational resources provided by the New York University New York, Abu Dhabi and Shanghai. The authors acknowledge the SXRD and PDF data collection by Dr. Zhao Pan, Dr. Tianwei Li, and Senior Scientist Dr. Yang Ren. This work was supported by the U.S. Department of Energy, Office of Science Basic Energy Sciences under grant DE‐SC0014520, DOE Office of Science (materials characterization, sample synthesis, transport properties). User Facilities were supported by the Office of Science of the U.S. Department of Energy under Contract Nos. 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 Tier 2 under Grant Nos. MOE2018‐T2‐1‐010, Singapore A*STAR Pharos Program SERC 1527200022, and Singapore A*STAR project A19D9a0096. The electron microscopy and XRD work were performed at the Facility for Analysis, Characterization, Testing and Simulation (FACTS), Nanyang Technological University, Singapore. The synchrotron radiation experiments were performed at the BL02B2 of SPring‐8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2021A1074). Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Science, under Contract DE‐AC02‐06CH11357. Y.‐W.F. acknowledges the computational resources provided by the New York University New York, Abu Dhabi and Shanghai. The authors acknowledge the SXRD and PDF data collection by Dr. Zhao Pan, Dr. Tianwei Li, and Senior Scientist Dr. Yang Ren.
Keywords
- crystal symmetry
- diamondoid structure
- nanoscale defects
- thermoelectrics
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- General Materials Science
