Synergistical Tuning Interface Barrier and Phonon Propagation in Au-Sb2Te3 Nanoplate for Boosting Thermoelectric Performance

Abstract

Engineering of low-dimensional metal-semiconductor nanocomposites is expected to decouple electrical and thermal property, leading to substantially higher thermoelectric property. In this study, we rationally design a unique 0D-2D Au-Sb2Te3 architecture with beneficial interface barrier and strengthened phonon scattering, resulting in synergistically optimized electrical and thermal properties. In-situ growth of Au nanoparticles ∼10 nm on Sb2Te3 nanoplates enables better manipulation of electron and phonon transport compared to traditional bulks. The energy barrier between Au and Sb2Te3 effectively filters low-energy holes, while the Au nanoparticles competently hinder the propagation of midto-long wavelength phonons. As a result, this unique 0D-2D Au-Sb2Te3 composite exhibits a concurrent increase in electrical conductivity and Seebeck coefficient, and a decrease in lattice thermal conductivity, which allows a double of ZT value (∼0.8 at 523 K) for 1 mol % Au-Sb2Te3 composites with respect to the pristine Sb2Te3 (∼0.39 at 523 K). This self-assembled heterostructure provides a direction to design other low-dimensional metal-semiconductor nanoassemblies for thermoelectric application.