Organic ligand displacement by metal salts to enhance nanoparticle functionality: thermoelectric properties of Ag2Te

The presence of organic ligands on the surface of colloidal nanoparticles strongly limits their performance in technological applications where charge carrier transfer/transport plays an important role. We use metal salts, matched with the nanoparticle composition, to eliminate the surface organic ligands without introducing extrinsic impurities in the final nanomaterial. The potential of the simple, general and scalable processes presented here is demonstrated by characterizing the thermoelectric properties of nanostructured Ag2Te produced by the bottom up assembly of Ag2Te nanocrystals. A 6-fold increase of the thermoelectric figure of merit of Ag2Te was obtained when organic ligands were displaced by AgNO3. The same procedure can enhance the performance of nanocrystals and nanocrystal-based devices in a broad range of applications, from photovoltaics and thermoelectrics to catalysis.