Self-assembly of a quantum dot superlattice using molecularly linked metal clusters

摘要

We report on a synthesis strategy for fabrication of close-packed planar arrays of nanometer-diameter metal clusters that are covalently linked by organic molecular wires. The clusters are gold single crystals, each encapsulated by a monolayer of dodecanethiol molecules. A colloidal suspension of these clusters in mesitylene is spread onto a flat, insulating substrate. On evaporation of the mesitylene the clusters self-assemble to form a close-packed monolayer. This two-dimensional cluster array is crosslinked by immersing it in an acetonitrile solution containing conjugated di-thiol or di-isonitrile molecules which serve as molecular wires. They displace some of the dodecanethiol molecules and form well defined tunnel junctions between adjacent clusters. This crosslinked network is a two-dimensional superlattice of metal quantum dots. When the clusters used to synthesize the network have diameters less than approximately 2 nm, it is predicted that this superlattice will exhibit Coulomb blockade effects at room temperature.