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

Intrinsic BiTe 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 BiTe, resulting in the difficulty of further property enhancement. In this work, the formation energy of native point defects in BiTe supercells and the electronic structure of BiTe primitive unit cell were calculated using first-principles. The antisite defect Bi_Te has a lower formation energy (0.68 eV) under the Te-lack condition for p-type BiTe. The effects of point defects on TE properties were investigated a series of p-type BiTe ( = 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 ( ) and *, the thermal conductivity ( ) was also cut down by the increased point defects. Benefitting from the high PF of 4.09 mW m K and the low of 1.77 W m K, the highest of 0.70 was obtained for = 0.06 composition at 300 K, which is 30% higher than that (0.54) of the intrinsic BiTe.