Tuning the Thermoelectric Performance of SnTe via Dual-Site Electronic Donation and Super-Saturation Solution

In this work, a dual-site electronic doping with Sb and I in SnTe has been carried out, and the impact of codoping on the electrical and thermal transport properties has been studied in detail. Due to the electron donation effect, the excessive hole density has been reduced, and the Seebeck coefficient (S) has been increased effectively. Moreover, transmission electron microscope (TEM) characterization analysis showed that a multiscale microstructure has been fabricated to suppress phonon propagation, thus decreasing the lattice thermal conductivity due to Sb content beyond its solubility limit. Combined with the enhancement of electronic transport properties and large reduction on thermal conductivity, a thermoelectric figure of merit of ∼0.97 at 873 K is obtained in the Sn0.88Sb0.12Te0.97I0.03 alloy, which is a 143% increase compared to that of the SnTe matrix.