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Title: Direct observation of vast off-stoichiometric defects in single crystalline SnSe

Single crystalline tin selenide (SnSe) recently emerged as a very promising thermoelectric material for waste heat harvesting and thermoelectric cooling, due to its record high figure of merit ZT in mediate temperature range. The most striking feature of SnSe lies in its extremely low lattice thermal conductivity as ascribed to the anisotropic and highly distorted Sn-Se bonds as well as the giant bond anharmonicity by previous studies, yet no theoretical models so far can give a quantitative explanation to such low a lattice thermal conductivity. Here, we presented direct observation of an astonishingly vast number of off-stoichiometric Sn vacancies and Se interstitials, using sophisticated aberration corrected scanning transmission electron microscope; and credited the previously reported ultralow thermal conductivity of the SnSe single crystalline samples partly to their off-stoichiometric feature. In order to further validate the conclusion, we also synthesized stoichiometric SnSe single crystalline samples, and illustrated that the lattice thermal conductivity is deed much higher as compared with the off-stoichiometric single crystals. Finally, the scattering efficiency of individual point defect on heat-carrying phonons was then discussed in the state-of-art Debye-Callaway model.
 [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [1] ;  [4] ;  [4] ;  [4] ;  [1] ;  [2] ;  [5] ;  [1]
  1. Southern Univ. of Science and Technology, Shenzhen (China). Dept. of Physics
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.
  3. Beihang Univ., Beijing (China). School of Materials Science and Engineering
  4. Chinese Academy of Sciences (CAS), Beijing (China). Ningbo Inst. of Materials Technology Technology and Engineering (NIMTE)
  5. Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry
Publication Date:
Report Number(s):
Journal ID: ISSN 2211-2855; R&D Project: MA015MACA; KC0201010; TRN: US1800312
Grant/Contract Number:
SC0012704; SC0014520
Accepted Manuscript
Journal Name:
Nano Energy
Additional Journal Information:
Journal Volume: 35; Journal Issue: C; Journal ID: ISSN 2211-2855
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Thermoelectricity; Transmission electron microscopy; Interstitial defects; Off-stoichiometry; Lattice thermal conductivity; SnSe
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1397491