A Chemically Soldered Polyoxometalate Single-Molecule Transistor.

Chuanli Wu,Xiaohang Qiao,Simon J Higgins,Andrea Vezzoli,Richard J Nichols,Chenxin Cai,Craig M Robertson

doi:10.1002/anie.202002174

Abstract

Polyoxometalates have been proposed in the literature as nanoelectronic components, where they could offer key advantages with their structural versatility and rich electrochemistry. Apart from a few studies on their ensemble behaviour (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, using the organic termini to chemically “solder” a single cluster to two nanoelectrodes. 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 mechanism with different charge‐transport probabilities through different charge states. Our results show the promise of polyoxometalates in nanoelectronics and give an insight on their single‐entity electrochemical behaviour.

Highlights

Assemblies of molecules, or even single molecules, might in the future offer new approaches to traditional nanoelectronics and nanofabrication, and contribute to scalability with a bottom-up selfassembly approach and miniaturisation.[1]
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
The MnMo6O24 oxide cluster core is capped with two 4-pyridyl moieties that act as contact to the electrodes, allowing the fabrication of single-POM junctions

Summary

Introduction

Assemblies of molecules, or even single molecules, might in the future offer new approaches to traditional nanoelectronics and nanofabrication, and contribute to scalability with a bottom-up selfassembly approach and miniaturisation.[1]. Stemming from the original studies employing simple aliphatic and conjugated, rod-like, oligoaryl moieties,[14] it is common to read reports on molecular wires incorporating fused polyaromatic/heterocyclic systems,[15,16] supramolecular complexes,[17,18] organometallic centres[19,20] and, more recently, polynuclear clusters.[21,22,23,24] The latter are interesting from a technology point of view for their electronic behaviour, as the presence of multiple metallic centres imparts stability to several oxidation states, with the cluster accommodating large charge variations These electron-sink phenomena[25] (i.e. clusters are able to accept and release electrons reversibly without significant changes in their structure) resulted in great interest in their synthesis and applications, especially as electroactive materials to be deployed in electronic, sensing and catalytic devices.[26,27]

Methods

Results

Conclusion