Insulator-to-metal transition in nanocrystal assemblies driven by in situ mild thermal annealing

We report on exploration of internanocrystal coupling in assemblies of CoPt₃ nanocrystals (i.e., artificial atom solids) probed by variable temperature charge transport measurements. Nanocrystal devices can be tuned in situ from Mott insulating to metallic behavior using mild thermal annealing. Thermal analysis suggests that the observed insulator-to-metal transition is due to melting and reorganization of the nanocrystal ligand shells causing a reduction in mean internanocrystal distance and is not due to nanocrystal ligand desorption or nanocrystal sintering.