Enhancement of Thermoelectric Properties in n-Type Cu0.01Bi2Te2.3+x Se0.7 (0 ≤ x ≤ 0.7) Compounds with Te-Excess

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 Te-Bi defects under a Te-rich condition for Cu0.01Bi2Te2.3+x Se-0.7 samples (0 ae x ae 0.7). The electrical resistivity decreases with increasing the amount of excess Te in the sample of Cu0.01Bi2Te2.3+x Se-0.7, 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 K-2 is obtained at 323 K for Cu0.01Bi2Te2.4Se0.7, which is enhanced by similar to 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 Te-Bi defects in n-type Bi2Te3-based materials should be effective for enhancing their thermoelectric performance. [GRAPHICS] .