High Thermoelectric Performance in 2D Sb₂Te₃ and Bi₂Te₃ Nanoplate Composites Enabled by Energy Carrier Filtering and Low Thermal Conductivity

Thermoelectrics are an important class of materials with great potential in alternative energy applications. In this study, two-dimensional (2D) nanoplates the layered chalcogenides, Sb2Te3 and Bi2Te3, synthesized composites two investigated for their thermoelectric properties. The materials, were as hexagonal, 2D via a colloidal polyol route. as-synthesized Bi2Te3 vary drastically from one another lateral vertical dimensions revealed by scanning electron microscopy atomic force microscopy. single crystalline nanoplate nature is deduced high-resolution transmission selected area diffraction. Nanoplates have well-defined hexagonal facets seen images. consolidated anisotropic nanostructured pellet spark plasma sintering. Preferred orientation observed powder X-ray diffraction pattern images fractured pellets confirm structure nanoplates. Thermoelectric properties parallel perpendicular directions measured, revealing strong anisotropy significant reduction to thermal conductivity direction due increased phonon scattering at interfaces. All compositions, except that 25% composite, behave degenerate semiconductors increasing electrical resistivity temperature increases. Seebeck coefficient also dramatically nanocomposites, highest reaching 210 μV/K 15% Bi2Te3. increase attributed carrier filtering Overall, these enhanced lead drastic performance direction, zT ∼ 1.26, composite 450 K.