Thermoelectric transport in surface- and antimony-doped bismuth telluride nanoplates

Abstract

We report the in-plane thermoelectric properties of suspended (Bi_1–xSb_x)₂Te₃ nanoplates with x ranging from 0.07 to 0.95 and thicknesses ranging from 9 to 42 nm. The results presented here reveal a trend of increasing p-type behavior with increasing antimony concentration, and a maximum Seebeck coefficient and thermoelectric figure of merit at x ~ 0.5. We additionally tuned extrinsic doping of the surface using a tetrafluoro-tetracyanoquinodimethane (F₄-TCNQ) coating. As a result, the lattice thermal conductivity is found to be below that for undoped ultrathin Bi₂Te₃ nanoplates of comparable thickness and in the range of 0.2–0.7 W m^–1 K^–1 at room temperature.