TY - JOUR
T1 - Direct observation of vast off-stoichiometric defects in single crystalline SnSe
AU - Wu, Di
AU - Wu, Lijun
AU - He, Dongsheng
AU - Zhao, Li Dong
AU - Li, Wei
AU - Wu, Minghui
AU - Jin, Min
AU - Xu, Jingtao
AU - Jiang, Jun
AU - Huang, Li
AU - Zhu, Yimei
AU - Kanatzidis, Mercouri G.
AU - He, Jiaqing
N1 - Funding Information:
This contribution was supported by the Natural Science Foundation of Guangdong Province (Grant No. 2015A030308001), the leading talents of Guangdong Province Program (Grant No. 00201517), and the Science, Technology and Innovation Commission of Shenzhen Municipality (Grant Nos. JCYJ201508311142508365, KQTD2016022619565991 and KQCX2015033110182370). TEM work at BNL was supported by the U.S. Department of Energy, Office of Basic Energy Science, Division of Materials Science and Engineering, under Contract No. DE-SC0012704. This work was also supported by NSFC under Grant Nos. 11504160, 51571007 and 51632005, and partly by the ?Zhuoyue? Program from Beihang University and the Recruitment Program for Young Professionals. At Northwestern University this project was supported by the Department of Energy, Office of Science Basic Energy Sciences grant DE-SC0014520. The authors appreciate the help of Prof. Wenyu Zhao from Wuhan University of Technology for the EPMA measurements.
PY - 2017/5/1
Y1 - 2017/5/1
N2 - 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. In this work, 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. 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. The scattering efficiency of individual point defect on heat-carrying phonons was then discussed in the state-of-art Debye-Callaway model.
AB - 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. In this work, 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. 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. The scattering efficiency of individual point defect on heat-carrying phonons was then discussed in the state-of-art Debye-Callaway model.
KW - Interstitial defects
KW - Lattice thermal conductivity
KW - Off-stoichiometry
KW - SnSe
KW - Thermoelectricity
KW - Transmission electron microscopy
UR - http://www.scopus.com/inward/record.url?scp=85017106227&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85017106227&partnerID=8YFLogxK
U2 - 10.1016/j.nanoen.2017.04.004
DO - 10.1016/j.nanoen.2017.04.004
M3 - Article
AN - SCOPUS:85017106227
VL - 35
SP - 321
EP - 330
JO - Nano Energy
JF - Nano Energy
SN - 2211-2855
ER -