A Chemically Soldered Polyoxometalate Single-Molecule Transistor

Polyoxometalates have been proposed in the literature as promising components for nanoelectronic applications, where they could offer key advantages with their structural versatility and rich electrochemistry. Apart from a few studies on their ensemble behaviour (for instance, as monolayers or thin films) this potential remains largely unexplored. We synthesised a pyridyl-capped Anderson-Evans polyoxometalate and used it to fabricate single-molecule junctions, by using the organic termini to chemically “solder” a single metal oxide cluster to two nanoelectrodes through coordination bonds. Operating the device in an electrochemical environment allowed us to probe charge transport through different oxidation states of the polyoxometalate, and we report here an efficient three-state transistor behaviour. Conductance data fits a quantum tunnelling transport mechanism, with charge having different tunnelling probabilities through different oxidation states of the polyoxometalate. Our results show the promise of such compounds in nanoelectronics, and are, to our best knowledge, the first report on the single-entity electrochemical behaviour of polyoxometalates.