Synergistic Optimization of Thermoelectric Performance of SnTe via In-Doping Induced Resonant Levels and Se/Cd-Doping Enhanced Phonon Scattering

SnTe is widely recognized as a promising alternative to environmentally harmful PbTe for thermoelectric applications at moderate and high temperatures. Nevertheless, due to the ultrahigh hole concentration as well as lattice thermal conductivity, the thermoelectric performance of pure SnTe is greatly constrained. In our work, a novel strategy was put forward to optimize the relatively poor thermoelectric performance of SnTe by simultaneously incorporating In2Se3 and Cd. The Seebeck coefficient was apparently improved through the whole temperature range originating from the introduction of resonant energy levels achieved by In doping, while lattice thermal conductivity was decreased to a relatively low level of ∼0.49 W m–1 K–1 at 873 K, owing to a decrease in sound velocity and strong scattering on phonon caused by nanopores and dislocations after doping. Profiting from the synergistic optimization thermoelectric performance strategies, a peak zT of 1.32 at 873 K was achieved in Sn0.96Cd0.04Te+1%In2Se3, which represents a remarkable 89% increase over pristine SnTe. And an average zT of 0.66 from 303 to 873 K was also obtained. Our work provides a new strategy for multifunctional synergistic modulation of the thermoelectric properties of SnTe-based materials.