Improved Thermoelectric Performance of P-type SnTe through Synergistic Engineering of Electronic and Phonon...

SnTe has been regarded as a potential alternative to PbTe in thermoelectrics because of its environmentally friendly features. However, it is a challenge to optimize its thermoelectric (TE) performance as it has an inherent high hole concentration (n_H∼2 × 10²⁰ cm^-3) and low mobility (μ_H∼18 cm² V^-1 s^-1) at room temperature (RT), arising from a high intrinsic Sn vacancy concentration and large energy separation between its light and heavy valence bands. Therefore, its TE figure of merit is only 0.38 at ∼900 K. Herein, both the electronic and phonon transports of SnTe were engineered by alloying species Ag_0.5Bi_0.5Se and ZnO in succession, thus increasing the Seebeck coefficient and, at the same time, reducing the thermal conductivity. As a result, the TE performance improves significantly with the peak ZT value of ∼1.2 at ∼870 K for the sample (SnGe_0.03Te)_0.9(Ag_0.5Bi_0.5Se)_0.1 + 1.0 wt % ZnO. This result proves that synergistic engineering of the electronic and phonon transports in SnTe is a good approach to improve its TE performance.