A simple Pb-doping to achieve bonding evolution, VSn and resonant level shifting for regulating thermoelectric transport behavior of SnTe

Abstract

The intensification of energy crises and environmental pollution inspire researchers' attention to environment-friendly SnTe thermoelectric materials. In this work, we achieved a lower lattice thermal conductivity and optimized the power factor via the synergistic optimization of bonding characteristic, VSn, and resonant level for the SnTe system, respectively. Pb-introduction produces weak bonding strength, mass fluctuation, and stress distortion, which result in lower thermal conductivity. The lowest lattice thermal conductivity achieves 0.66 W m–1 K–1 at 773 K. Further introduced VSn relieves loss of electrical conductivity caused by Pb-introduction, and it also makes the bigger g(E) and up-shift of resonance level. The VSn, enhanced g(E), and resonant level make electrical conductivity and Seebeck coefficient enhance simultaneously. Finally, the further optimization of thermal and electronic transport performance contributes to a higher ZT value of ∼0.86 at 773 K in the Sn0.685Pb0.285In0.015Te0.7Se0.3 sample. The strategy of bonding characteristic, VSn, and resonant level synergistic engineering will be widely applicable to various TE systems for achieving better thermoelectric performance.