Single-Electron Currents in Designer Single-Cluster Devices

Abstract

Atomically precise clusters can be used to create single-electron devices wherein a single redox-active cluster is connected to two macroscopic electrodes via anchoring ligands. Unlike single-electron devices comprising nanocrystals, these cluster-based devices can be fabricated with atomic precision. This affords an unprecedented level of control over the device properties. Herein, we design a series of cobalt chalcogenide clusters with varying ligand geometries and core nuclearities to control their current−voltage (I−V) characteristics in a scanning tunneling microscope-based break junction (STM-BJ) device. First, the device geometry is modified by precisely positioning junction-anchoring ligands on the surface of the cluster. We show that the I−V characteristics are independent of ligand placement, confirming a sequential, single-electron tunneling mechanism. Next, we chemically fuse two clusters to realize a larger cluster dimer that behaves as a single electronic unit, possessing a smaller reorganization energy and more accessible redox states than the monomeric analogues. As a result, dimer-based devices exhibit significantly higher currents and can even be pushed to current saturation at high bias. Owing to these controllable properties, single-cluster junctions serve as an excellent platform for exploring incoherent charge transport processes at the nanoscale. With this understanding, as well as properties such as nonlinear I−V characteristics and rectification, these molecular clusters may function as conductive inorganic nodes in new devices and materials.

Towards Quantum Computing with Molecular Electronics

“…The theory of single-molecule transport, including the role of quantum interference, has developed considerably since [24,28,29,[36][37][38][39][40]. We are interested in exploring the use of molecules for quantum computing because (1) molecules are extremely small, typically on the order of 1 to 10nm in size, and thus computation with molecules operate within the regime of quantum mechanical effects, (2) Quantum interference effects in molecules are potentially robust to external perturbation [26,38,41], and (3) molecules may be easier and cheaper to fabricate than e.g. superconducting qubits.…”

Electron transport properties of PAl12-based cluster complexes

“…Moreover, conventional single molecular junction also suffers from some significant limitations such as low-temperature dependence and coherent tunneling. 7 As Moore's law is faltering 8 , scientists are now trying to use different components to increase the computer's computing power, like using carbon nanotubes, nanoclusters, or quantum transistors. Recent researches have shown promising transport results for metal 9,10 and metal chalcogenide 7,11 clusters.…”

“…7 As Moore's law is faltering 8 , scientists are now trying to use different components to increase the computer's computing power, like using carbon nanotubes, nanoclusters, or quantum transistors. Recent researches have shown promising transport results for metal 9,10 and metal chalcogenide 7,11 clusters. It was also noticed that by using such nanoclusters for charge transport, one could circumvent the limitations of common organic or organometallic molecules.…”

“…It was also noticed that by using such nanoclusters for charge transport, one could circumvent the limitations of common organic or organometallic molecules. 7 In the spirit of this, semiconducting cluster complexes constituted of atomic clusters and choices of ligands are proposed to mimic the functions of transistors to achieve the goal of increasing computing power.…”

Superatom Regiochemistry Dictates the Assembly and Surface Reactivity of a Two-Dimensional Material

“…The key feature of this new 2D material is that its surfaces are passivated with photolabile CO ligands offering unique possibilities for surface functionalization. The photoinduced exchange of CO for phosphines and isocyanides on Co 6 Se 8 clusters has been demonstrated in solution − but not in the solid state. As a first demonstration, we functionalize exfoliated flakes of 2 with 4-isocyano­azobenzene (CNAB), which allows us to monitor the reaction by Raman spectroscopy.…”