Synergistic band convergence and defect engineering boost thermoelectric performance of SnTe

As an eco-friendly thermoelectric material, SnTe has attracted extensive attention. In this study, we use a stepwise strategy to enhance the thermoelectric performance of SnTe. Firstly, AgCl is doped into SnTe to realize band convergence and enlarge the band gap of AgCl-doped SnTe. AgCl-doping also induces dense point defects , strengthens the phonon scattering, and reduces the lattice thermal conductivity . Secondly, Sb is alloyed into AgCl-doped SnTe to further optimize the carrier concentration and simultaneously reduce the lattice thermal conductivity , leading to improved thermoelectric dimensionless figure of merit, ZT . Finally, (Sn 0.81 Sb 0.19 Te) 0.93 (AgCl) 0.07 has approached the ZT value as high as ∼0.87 at 773 K, which is 272 % higher than that of pristine SnTe. This study indicates that stepwise AgCl-doping and Sb-alloying can significantly improve thermoelectric performance of SnTe due to synergistic band engineering, carrier concentration optimization and defect engineering.