Bi 2 Te 3 single crystals with high room-temperature thermoelectric performance enhanced by manipulating point defects based on first-principles calculation.

Intrinsic Bi 2 Te 3 is a representative thermoelectric (TE) material with high performance at low temperature, which enables applications for electronic cooling. However, antisite defects easily form in p-type Bi 2 Te 3 , resulting in the difficulty of further property enhancement. In this work, the formation energy of native point defects in Bi 2 Te 3 supercells and the electronic structure of Bi 2 Te 3 primitive unit cell were calculated using first-principles. The antisite defect Bi_Te 1 has a lower formation energy (0.68 eV) under the Te-lack condition for p-type Bi 2 Te 3 . The effects of point defects on TE properties were investigated via a series of p-type Bi 2 Te 3- x ( x = 0, 0.02, 0.04, 0.06, 0.08) single crystals prepared by the temperature gradient growth method (TGGM). Apart from the increased power factor (PF ∥ ) which originates from the increased carrier concentration ( n ∥ ) and m *, the thermal conductivity ( κ ∥ ) was also cut down by the increased point defects. Benefitting from the high PF ∥ of 4.09 mW m -1 K -2 and the low κ ∥ of 1.77 W m -1 K -1 , the highest ZT ∥ of 0.70 was obtained for x = 0.06 composition at 300 K, which is 30% higher than that (0.54) of the intrinsic Bi 2 Te 3 .