A significant obstacle to obtaining enhanced thermoelectric performance (defined by a thermoelectric figure of merit, zT) in commercial p-type Bi-Sb-Te alloys is bipolar transport originating from their intrinsic narrow-band-gap semiconducting characteristics. Cation-site doping is commonly used to suppress the bipolar conduction. However, zT enhancement occurs often only at elevated temperatures since the electronic thermal conductivity mainly increases at low temperatures due to the increase of hole concentration. Herein, the substitution of isovalent S ions in the anion Te-site of Bi-Sb-Te is explored to obtain a high zT over a wide temperature range by simultaneously increasing the density-of-states effective mass and weighted mobility. The zT of Bi0.49Cu0.01Sb1.5Te3 is enhanced by ~10 % for all measured temperatures, and the average zT increases beyond 1.0 between 300 and 520 K, benefitting from the synergetic control of band structure and deformation potential via S substitution.
Bibliographical noteFunding Information:
This research was supported by the Global Frontier Program through the Global Frontier Hybrid Interface Materials (GFHIM) project (Grant2013M3A6B1078870) and the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2019R1A6A1A11055660). This work was also supported by the Technology Innovation Program (20000149, Development of non-rare half-Heusler thermoelectric alloys for mid to high temperature waste heat recovery) funded By the Ministry of Trade, Industry & Energy (MOTIE, Korea).
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All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys