Enhancement of Thermoelectric Properties in n-Type Cu0.01Bi2Te2.3+xSe0.7 (0 ≤ x ≤ 0.7) Compounds with Te-Excess
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The fine control of antisite defects for Bi2Te3-based materials is necessary to improve their thermoelectric performance using the optimization of a carrier concentration. In this work, we attempted to tune the n-type carrier concentration by forming antisite TeBi defects under a Te-rich condition for Cu0.01Bi2Te2.3+xSe0.7 samples (0 ≤ x ≤ 0.7). The electrical resistivity decreases with increasing the amount of excess Te in the sample of Cu0.01Bi2Te2.3+xSe0.7, which is originated from the increase in the electron carrier concentration for the Te-excess samples. The highest power factor of 2.72 mW/m K2 is obtained at 323 K for Cu0.01Bi2Te2.4Se0.7, which is enhanced by ~ 20% compared to the x = 0 sample. The highest ZT of 0.92 is achieved at 473 K for Cu0.01Bi2Te2.4Se0.7, which is 11% higher than that of x = 0 sample (ZT = 0.83). We demonstrate that the optimization of n-type carrier concentration by forming antisite TeBi defects in n-type Bi2Te3-based materials should be effective for enhancing their thermoelectric performance.
KeywordsThermoelectric Bismuth telluride Antisite defect Thermal conductivity Seebeck coefficient
This research was supported by Nano Material Technology Development Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2011-0030147) and by the Materials and Components Technology Development Program of MOTIE/KEIT (10063286).
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