Realizing high thermoelectric performance in N-type Bi2Te3 compounds by Sb nano-precipitates

Abstract

Driven by the prospective application of thermoelectric (TE) materials, massive efforts have been devoted to improving its performance. However, strong-coupled thermal and electrical transport is still the largest block for the promotion of TE techniques. Here, we report a peak ZT over 1.2 at 400 K in an n-type Bi2Te2.7Se0.3 sample doped by 5 wt. % Sb under the spark plasma sintering method. This high performance is attributed to the synergistically optimized thermal and electrical transport properties. Sb nano-precipitates, which have been observed directly by spherical aberration-corrected transmission electron microscopy, substantially decrease the lattice thermal conductivity of the sample, leading to a low value of 0.35 W m−1 K−1. Meanwhile, band bending caused by the nano-precipitates significantly enhances the Seebeck coefficient, resulting in a high PF of 35 μW cm−1 K−2. The study about optimizing electrical and thermal properties simultaneously opens the door to the high performance of Bi2Te3-based materials.