Carrier tuning and multiple phonon scattering induced high thermoelectric performance in n-type Sb-doped PbTe alloys

Much progress on highly efficient thermoelectric materials have been made in the p-type PbTe. However, the n-type PbTe only shows a relatively low figure of merit ZT and conversion efficiency $\eta$, which is urgently required to be strengthened and compatible with p-type counterpart from the viewpoint of large-scale applications. Here, we report that n-type Sb-doped PbTe alloys can directly improve the power factor owing to the optimized carrier concentration. Moreover, the unexpected synergistic effect, deriving from alloying and nano-precipitates scattering due to Sb doping, triggers a dramatic reduction of lattice thermal conductivity. Consequently, a remarkable ZT of $\sim$ 1.3 at 673 K in n-type Pb${}_{0.98}$Sb${}_{0.02}$Te and the average ZT${}_{ave}$ of $\sim$ 0.83 with the calculated conversion efficiency $\eta$ of $\sim$ 12.3% in a wide temperature range from 323 to 823 K are achieved. The present findings demonstrate the excellent potential in n-type Sb-doped PbTe thermoelectric materials through a synergetic carrier tuning and multiple phonon scattering strategy, which provides a new avenue for exploring high-performance thermoelectric materials in n-type PbTe and/or other materials. (orig.)