Facile fabrication of bulk nanostructured thermoelectric materials via ligand exchange-enabled integration of colloidal nanoparticles

Incorporating nanostructures into bulk thermoelectric (TE) materials is a promising strategy for enhancing their performance, but scalable and versatile fabrication methods remain limited. In this study, we present a simple and general approach to produce bulk nanostructured TE materials by uniformly decorating thermoelectric powders with colloidal nanoparticles through a ligand exchange-assisted process. As a model system, colloidal Au nanoparticles and Bi-Te-based thermoelectric powders were used to demonstrate the method. This process enables homogeneous nanoparticle distribution and significantly reduces surface organic residues that hinder electrical transport. The resulting composite powders can be consolidated into dense bulk materials using low-temperature sintering, while retaining well-distributed nanostructures along grain boundaries. Microstructural analysis confirms the effective integration of nanoparticles into the TE matrix, leading to enhanced phonon scattering and improved thermoelectric properties. The process is applicable to a wide range of thermoelectric materials and nanoparticle systems, offering a practical and scalable route for designing high-performance TE materials through controlled nanostructuring.