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Title: Enhanced thermoelectric performance in Cu-intercalated BiTeI by compensation weakening induced mobility improvement

Abstract

The low weighted carrier mobility has long been considered to be the key challenge for improvement of thermoelectric (TE) performance in BiTeI. The Rashba-effect-induced two-dimensional density of states in this bulk semiconductor is beneficial for thermopower enhancement, which makes it a prospective compound for TE applications. In this report, we show that intercalation of minor Cu-dopants can substantially alter the equilibria of defect reactions, selectively mediate the donor-acceptor compensation, and tune the defect concentration in the carrier conductive network. Consequently, the potential fluctuations responsible for electron scattering are reduced and the carrier mobility in BiTeI can be enhanced by a factor of two to three between 10 K and 300 K. The carrier concentration can also be optimized by tuning the Te/I composition ratio, leading to higher thermopower in this Rashba system. Cu-intercalation in BiTeI gives rise to higher power factor, slightly lower lattice thermal conductivity, and consequently improved figure of merit. Compared with pristine BiTe 0.98I 1.02, the TE performance in Cu 0.05BiTeI reveals a 150% and 20% enhancement at 300 and 520 K, respectively. Ultimately, these results demonstrate that defect equilibria mediated by selective doping in complex TE and energy materials could be an effective approach to carriermore » mobility and performance optimization.« less

Authors:
 [1];  [2];  [3];  [4];  [4];  [5];  [6];  [4]
  1. Chinese Academy of Sciences, Shanghai (China); Univ. of Washington, Seattle, WA (United States); Shanghai Univ., Shanghai (China)
  2. Univ. of Washington, Seattle, WA (United States); Shanghai Univ., Shanghai (China)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Univ. of Washington, Seattle, WA (United States)
  5. Chinese Academy of Sciences, Shanghai (China); Shanghai Univ., Shanghai (China)
  6. Chinese Academy of Sciences, Shanghai (China)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org.:
National Science Foundation (NSF); National Basic Research Program of China; USDOE Office of Science (SC)
OSTI Identifier:
1259710
Alternate Identifier(s):
OSTI ID: 1265785
Grant/Contract Number:
FC26-04NT42278; 2013CB632501; 11234012; 1235535; AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 5; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; electronic properties and materials; semiconductors; 36 MATERIALS SCIENCE

Citation Formats

Wu, Lihua, Yang, Jiong, Chi, Miaofang, Wang, Shanyu, Wei, Ping, Zhang, Wenqing, Chen, Lidong, and Yang, Jihui. Enhanced thermoelectric performance in Cu-intercalated BiTeI by compensation weakening induced mobility improvement. United States: N. p., 2015. Web. doi:10.1038/srep14319.
Wu, Lihua, Yang, Jiong, Chi, Miaofang, Wang, Shanyu, Wei, Ping, Zhang, Wenqing, Chen, Lidong, & Yang, Jihui. Enhanced thermoelectric performance in Cu-intercalated BiTeI by compensation weakening induced mobility improvement. United States. doi:10.1038/srep14319.
Wu, Lihua, Yang, Jiong, Chi, Miaofang, Wang, Shanyu, Wei, Ping, Zhang, Wenqing, Chen, Lidong, and Yang, Jihui. Wed . "Enhanced thermoelectric performance in Cu-intercalated BiTeI by compensation weakening induced mobility improvement". United States. doi:10.1038/srep14319. https://www.osti.gov/servlets/purl/1259710.
@article{osti_1259710,
title = {Enhanced thermoelectric performance in Cu-intercalated BiTeI by compensation weakening induced mobility improvement},
author = {Wu, Lihua and Yang, Jiong and Chi, Miaofang and Wang, Shanyu and Wei, Ping and Zhang, Wenqing and Chen, Lidong and Yang, Jihui},
abstractNote = {The low weighted carrier mobility has long been considered to be the key challenge for improvement of thermoelectric (TE) performance in BiTeI. The Rashba-effect-induced two-dimensional density of states in this bulk semiconductor is beneficial for thermopower enhancement, which makes it a prospective compound for TE applications. In this report, we show that intercalation of minor Cu-dopants can substantially alter the equilibria of defect reactions, selectively mediate the donor-acceptor compensation, and tune the defect concentration in the carrier conductive network. Consequently, the potential fluctuations responsible for electron scattering are reduced and the carrier mobility in BiTeI can be enhanced by a factor of two to three between 10 K and 300 K. The carrier concentration can also be optimized by tuning the Te/I composition ratio, leading to higher thermopower in this Rashba system. Cu-intercalation in BiTeI gives rise to higher power factor, slightly lower lattice thermal conductivity, and consequently improved figure of merit. Compared with pristine BiTe0.98I1.02, the TE performance in Cu0.05BiTeI reveals a 150% and 20% enhancement at 300 and 520 K, respectively. Ultimately, these results demonstrate that defect equilibria mediated by selective doping in complex TE and energy materials could be an effective approach to carrier mobility and performance optimization.},
doi = {10.1038/srep14319},
journal = {Scientific Reports},
number = ,
volume = 5,
place = {United States},
year = {Wed Sep 23 00:00:00 EDT 2015},
month = {Wed Sep 23 00:00:00 EDT 2015}
}

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  • The low weighted carrier mobility has long been considered to be the key challenge for improvement of thermoelectric (TE) performance in BiTeI. The Rashba-effect-induced two-dimensional density of states in this bulk semiconductor is beneficial for thermopower enhancement, which makes it a prospective compound for TE applications. In this report, we show that intercalation of minor Cu-dopants can substantially alter the equilibria of defect reactions, selectively mediate the donor-acceptor compensation, and tune the defect concentration in the carrier conductive network. Consequently, the potential fluctuations responsible for electron scattering are reduced and the carrier mobility in BiTeI can be enhanced by amore » factor of two to three between 10 K and 300 K. The carrier concentration can also be optimized by tuning the Te/I composition ratio, leading to higher thermopower in this Rashba system. Cu-intercalation in BiTeI gives rise to higher power factor, slightly lower lattice thermal conductivity, and consequently improved figure of merit. Compared with pristine BiTe0.98I1.02, the TE performance in Cu0.05BiTeI reveals a 150% and 20% enhancement at 300 and 520 K, respectively. These results demonstrate that defect equilibria mediated by selective doping in complex TE and energy materials could be an effective approach to carrier mobility and performance optimization.« less
  • The electronic structures were calculated for BiTeBr and BiTeI using the density-functional theory approach and accounting for the strong spin-orbital interaction. Qualitatively, the band structures for two compounds are similar, showing strong mixing of the p states of all elements in vicinity of the Fermi level, with the band gaps of 0.595 and 0.478 eV for BiTeBr and BiTeI, respectively. The optimized crystal structures show a tendency for the Bi-X (X=Br, I) bond elongation compared to the Bi-Te one. Both compounds are intrinsic n-type semiconductors but display a metallic-like conductivity coupled to rather large thermopower, which is rationalized within themore » frames of the acoustic phonons scattering model. Because of larger thermopower BiTeBr exhibits a twice higher thermoelectric figure-of-merit near room temperature, ZT=0.17, compared to BiTeI. The addition of 1 mass% of BiI{sub 3} or CuI to BiTeI decreases the mobility of electrons by two orders of magnitude, leading to significantly lower electrical conductivity, but at the same time effectively reduces the thermal conductivity. The prospects of further enhancing the thermoelectric efficiency are briefly discussed. - Graphical abstract: View of the crystal structure of BiTeBr is shown in the figure The optimized crystal structures show a tendency for the Bi-X (X=Br, I) bond elongation compared to the Bi-Te one. The electronic structures were calculated for BiTeBr and BiTeI using the density-functional theory approach and accounting for the strong spin-orbital interaction. Qualitatively, the band structures for two compounds are similar, showing strong mixing of the p states of all elements in vicinity of the Fermi level, with the band gaps of 0.595 and 0.478 eV for BiTeBr and BiTeI, respectively. Both compounds are intrinsic n-type semiconductors but display a metallic-like conductivity coupled to rather large thermopower, which is rationalized within the frames of the acoustic phonons scattering model. The addition of 1 mass% of BiI{sub 3} or CuI to BiTeI effectively reduces the thermal conductivity. The prospects of further enhancing the thermoelectric efficiency are briefly discussed. Highlights: Black-Right-Pointing-Pointer BiTeBr and BiTeI feature mixing of p states of Bi, Te, and halogen near Fermi level. Black-Right-Pointing-Pointer BiTeBr has thermoelectric figure-of-merit ZT=0.17, two times that of BiTeI. Black-Right-Pointing-Pointer 1% CuI or BiI{sub 3} decrease dramatically electron mobility in BiTeI. Black-Right-Pointing-Pointer 1% CuI decreases thermal conductivity of BiTeI by a factor of 4, reaching 0.5 W m{sup -1} K.« less
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  • Superionic chalcopyrites have recently attracted interest in their use as potential thermoelectric materials because of extraordinary low thermal conductivities. To overcome long-term stability issues in thermoelectric generators using superionic materials at evaluated temperatures, materials need to be found that show good thermoelectric performance at moderate temperatures. Here, we present the structural and thermoelectric properties of the argyrodite Ag 8SiSe 6, which exhibits promising thermoelectric performance close to room temperature.