Boosting Thermoelectric Performance of Bi2Te3 Material by Microstructure Engineering

Abstract Due to the intrinsic contradiction of electrical conductivity and Seebeck coefficient in thermoelectric materials, the enhancement for the power factor ( PF ) is limited. Since the PF decides the output power, strategies to the enhancement of PF are of paramount importance. In this work, Bi 2 Te 3 /Sb and Bi 2 Te 3 /W multilayer films are proposed to enhance the thermoelectric properties. Both systems possess extremely high conductivity of ≈5.6 × 10 5 S m −1 . Moreover, the electrical conductivity and Seebeck coefficient simultaneously increase as temperature rising, showing the overcome of the intrinsic contradiction. This results in ultrahigh PF s of 1785 µWm −1 K −2 for Bi 2 Te 3 /W and of 1566 µWm −1 K −2 for Bi 2 Te 3 /Sb at 600 K. Thermal heating of the Bi 2 Te 3 /Sb multilayer system shows compositional changes with subsequent formation of Bi‐Te‐Sb phases, Sb‐rich Bi‐Te precipitates, and cavities. Contrary, the multilayer structure of the Bi 2 Te 3 /W films is maintained, while Bi 2 Te 3 grains of high‐crystalline quality are confined between the W layers. In addition, bilayer defects in Bi 2 Te 3 and smaller cavities at the interface to W layers are also observed. Thus, compositional and confinement effects as well as structural defects result in the ultrahigh PF . Overall, this work demonstrates the strategies on how to obtain ultrahigh PF s of commercial Bi 2 Te 3 material by microstructure engineering using multilayer structures.