Enhanced thermoelectric performance in p-type (Bi, Sb)2Te3 materials via anomalous PbBr2 doping
Bismuth telluride-based materials has been applied in thermoelectric cooling wildly, but the properties still can be further enhanced by doping, microstructure controlling and compositing strategies. Herein, we demonstrate an anomalous doping strategy in (Bi, Sb) 2 Te 3 (BST) materials, where the strong n type dopant of PbBr 2 acts as p-type dopant, introducing holes in BST materials. The anomalous doping is attributed to the dissolution of Pb and Br elements into the matrix in a non-stoichiometric ratio, with Pb predominantly occupying Sb vacancies and Br enriching the in-situ generated Sb 2 O 3 , resulting in the increased hole concentration and improved electrical conductivity. The maximum power factor (PF) ultimately increases to 3972 μW m −1 K −2 for the 0.3 mol% PbBr 2 doped BST sample. Moreover, the enhanced multi-scale wavelength phonon scattering centers cause the lattice thermal conductivity fall to 0.52 W m −1 K −1 . Finally, the peak ZT is effectively enhanced to 1.3 at 323 K, which is 22 % higher than that of pristine sample. Furthermore, a direct conversion efficiency of 4.6 % is achieved in a single 0.3 mol% PbBr 2 -doped BST leg at a temperature gradient of ΔT = 200 K. Thus, this study underscores the anomalous PbBr 2 doping in Bi 0.42 Sb 1.58 Te 3 , promoting the wider application of BST-based materials.
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