Investigation on halogen-doped n-type SnTe thermoelectrics

Recent theoretical predictions and experimental findings on the transport properties of n-type SnTe have triggered extensive researches on this simple binary compound, despite the realization of n-type SnTe being a great challenge. Herein, Cl as a donor dopant can effectively regulate the position of Fermi level in Sn_0.6Pb_0.4Te matrix and successfully achieve the n-type transport behavior in SnTe. An outstanding power factor of ~ 14.7 µW·cm^‑1·K^‑2 at 300 K was obtained for Cl-doped Sn_0.6Pb_0.4Te sample. By combining the experimental analysis with theoretical calculations, the transport properties of n-type SnTe thermoelectrics doped with different halogen dopants (Cl, Br, and I) were then systematically investigated and estimated. The results demonstrated that Br and I had better doping efficiencies compared with Cl, which contributed to the well-optimized carrier concentrations of ~ 1.03 × 10¹⁹ and ~ 1.11 × 10¹⁹ cm^‑3 at 300 K, respectively. The improved n-type carrier concentrations effectively lead to the significant enhancement on the thermoelectric performance of n-type SnTe. Our study further promoted the experimental progress and deep interpretation of the transport features in n-type SnTe thermoelectrics. The present results could also be crucial for the development of n-type counterparts for SnTe-based thermoelectric devices.