Tailoring the Carrier and Phonon Scattering to Enhanced Thermoelectric Performance of SnTe by Cation–Anion Codoping with Eco-Benign CaI2

Abstract

In this work, earth abundant CaI2 compound has been applied to regulate the thermoelectric performance of SnTe by codoping in both the anion and cation sites for the first time. The carrier concentration has been effectively tuned to a reasonable range due to the electron donor nature of ITe+ point defects; on the other hand, the Seebeck coefficient has been significantly enhanced because of the resulted valence band convergence and band gap enlargement. More importantly, the phonon and carrier scattering have been tailored tactically, and a relatively high power factor with a significantly lowered thermal conductivity have been achieved simultaneously. In consequence, an enhanced figure of merit ZT ∼1.2 at 873 K was attained in the SnTe-3% CaI2 sample.