Improved\nThermoelectric Performance of P‑type\nSnTe through Synergistic Engineering of Electronic and Phonon Transports

Abstract

SnTe\nhas been regarded as a potential alternative to PbTe in thermoelectrics\nbecause of its environmentally friendly features. However, it is a\nchallenge to optimize its thermoelectric (TE) performance as it has\nan inherent high hole concentration (<i>n</i>_H∼2 × 10²⁰ cm^–3) and low\nmobility (μ_H∼18 cm² V^–1 s^–1) at room temperature (RT), arising from a\nhigh intrinsic Sn vacancy concentration and large energy separation\nbetween its light and heavy valence bands. Therefore, its TE figure\nof merit is only 0.38 at ∼900 K. Herein, both the electronic\nand phonon transports of SnTe were engineered by alloying species\nAg_0.5Bi_0.5Se and ZnO in succession, thus increasing\nthe Seebeck coefficient and, at the same time, reducing the thermal\nconductivity. As a result, the TE performance improves significantly\nwith the peak ZT value of ∼1.2 at ∼870 K for the sample\n(SnGe_0.03Te)_0.9(Ag_0.5Bi_0.5Se)_0.1 + 1.0 wt % ZnO. This result proves that synergistic\nengineering of the electronic and phonon transports in SnTe is a good\napproach to improve its TE performance.