Realizing High Thermoelectric Performance in Bi0.4Sb1.6Te3 Nanosheets by Doping Sn Element

The bottom-up method has been universally used to synthesize low-dimensional nanomaterials because the existence of a large number of interfaces contributes to low thermal conductivity compared to the top-down method. In this work, SnxBi0.4-xSb1.6Te3 (abbreviated as SnxBST, where x = 0, 0.04, 0.06, or 0.08) ingots are synthesized by a one-step hydrothermal method, combining a fast annealing technique with a high-temperature sintering technique. The existence of defects contributes to the dramatic increase of carrier concentration and then optimizes the electrical conductivity. The maximum power factor (PF) value is 3.11 mW/m/K2 for the Sn0.08BST thermoelectric ingot, which is an increase of 1.59 times compared to that of the pure sample at room temperature. Moreover, the maximum weighted mobility (μw) value is 339.1 cm2/(V·s) at 303 K, which is 1.54 times that of the pure sample. By considering the anisotropy of the thermal conductivity, combining PF perpendicular to the pressure direction and thermal conductivity along the pressure direction, the over-estimated ZTmax and ZTave values are up to 1.34 at 393 K and 1.24 between 303 and 483 K, respectively, which are 1.43 and 1.52 times those of the pure sample, respectively. Finally, this work could be extended to apply to the synthesis of thermoelectric materials via solvothermal methods.