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Published October 2017 | Supplemental Material
Journal Article Open

High thermoelectric performance in (Bi_(0.25)Sb_(0.75)_2 Te_3 due to band convergence and improved by carrier concentration control


Bi_2Te_3 has been recognized as an important cooling material for thermoelectric applications. Yet its thermoelectric performance could still be improved. Here we propose a band engineering strategy by optimizing the converging valence bands of Bi_2Te_3 and Sb_2Te_3 in the (Bi_(1−x)Sb_x)_2Te_3 system when x = 0.75. Band convergence successfully explains the sharp increase in density-of-states effective mass yet relatively constant mobility and optical band gap measurement. This band convergence picture guides the carrier concentration tuning for optimum thermoelectric performance. To synthesize homogeneous textured and optimally doped (Bi0.25Sb0.75)2Te3, excess Te was chosen as the dopant. Uniform control of the optimized thermoelectric composition was achieved by zone-melting which utilizes separate solidus and liquidus compositions to obtain zT = 1.05 (at 300 K) without nanostructuring.

Additional Information

© 2017 Elsevier Ltd. Available online 28 June 2017. The authors would like to acknowledge funding from the Solid-State Solar-Thermal Energy Conversion Center (S3TEC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0001299. H.-S. Kim gratefully acknowledge financial support from Samsung Advanced Institute of Technology (SAIT). H.-S. Kim would like to thank fruitful discussions with Prof. Yanzhong Pei (Tongji University) and Dr. Heng Wang (University of California, Berkeley). Lastly, H.-S. Kim would also like to acknowledge the time and efforts that Prof. Teruyuki Ikeda (Ibaraki University) has put to build the zone-levelling furnace used in the lab.

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August 19, 2023
October 26, 2023