High thermoelectric and mechanical performance in strong-textured n-type Bi2Te2.7Se0.3 by temperature gradient method

Bismuth telluride is the only commercially available thermoelectric material, but the poor n-type thermoelectric performance restricts its further development. Herein, we report the n-type Bi2Te2.7Se0.3 + x wt% PbI2 polycrystalline with both high texture degree and various microstructures by the temperature gradient method. Based on the superior carrier mobility maintained by high grain orientation, dilute PbI2 doping not only tunes the carrier concentration to an optimal level but also induces multiscale phonon scattering centers to realize a very low lattice thermal conductivity. As a result, a peak ZT of 1.26 at 350 K, a high ZTavg of 1.22 (300–400 K), and an improved Vickers hardness of 0.48 GPa are realized in Bi2Te2.7Se0.3 + 0.22 wt% PbI2 sample. This work suggests that the dilute PbI2 doping by temperature gradient method is an effective solution for preparation of n-type bismuth telluride materials with both high thermoelectric and moderate mechanical properties.