Interface-engineered melt-spun BiSbTe for multiscale phonon scattering and enhanced thermoelectric performance

Abstract

Thermoelectric materials have attracted tremendous attention owing to their capability to directly convert heat and electricity. Enhancing thermoelectric efficiency of materials relies on minimizing thermal conductivity via phonon scattering engineering, where the broad spectrum of phonon frequencies requires multiscale architectures capable of scattering phonons over diverse wavelengths. In this study, we developed BiSbTe-based thermoelectric materials featuring multiscale hierarchical microstructures, achieved via melt-spinning synthesis of nanostructured BiSbTe particles followed by solutionphase coating with polyoxometalates (POMs). During spark plasma sintering, the POM surface layers decompose to form ultrathin oxide interfacial layers within the BiSbTe grains. These oxide interfaces, in combination with nanoscale features, effectively suppress lattice thermal conductivity to 0.38 W m⁻¹ K⁻¹ at room temperature with only 0.1 mol% POM additive, yielding a peak figure of merit (ZT) of 1.56 at 75 °C. This work demonstrates a scalable strategy for realizing multiscale phonon scattering and enhanced thermoelectric performance through interface engineering.