All wired up: New molecular wires for single-molecule electronic devices

August 28, 2018

Scientists at Tokyo Institute of Technology designed a new type of molecular wire doped with organometallic ruthenium to achieve unprecedentedly higher conductance than earlier molecular wires. The origin of high conductance in these wires is fundamentally different from similar molecular devices and suggests a potential strategy for developing highly conducting "doped" molecular wires.

Since their conception, researchers have tried to shrink electronic devices to unprecedented sizes, even to the point of fabricating them from a few molecules. Molecular wires are one of the building blocks of such minuscule contraptions, and many researchers have been developing strategies to synthesize highly conductive, stable wires from carefully designed molecules.

A team of researchers from Tokyo Institute of Technology, including Yuya Tanaka, designed a novel molecular wire in the form of a metal electrode-molecule-metal electrode (MMM) junction including a polyyne, an organic chain-like molecule, "doped" with a ruthenium-based unit Ru(dppe)2. The proposed design, featured in the cover of the Journal of the American Chemical Society, is based on engineering the energy levels of the conducting orbitals of the atoms of the wire, considering the characteristics of gold electrodes.

Using scanning tunneling microscopy, the team confirmed that the conductance of these molecular wires was equal to or higher than those of previously reported organic molecular wires, including similar wires "doped" with iron units. Motivated by these results, the researchers then went on to investigate the origin of the proposed wire's superior conductance. They found that the observed conducting properties were fundamentally different from previously reported similar MMM junctions and were derived from orbital splitting. In other words, orbital splitting induces changes in the original electron orbitals of the atoms to define a new "hybrid" orbital facilitating electron transfer between the metal electrodes and the wire molecules. According to Tanaka, "such orbital splitting behavior has rarely been reported for any other MMM junction".

Since a narrow gap between the highest (HOMO) and lowest (LUMO) occupied molecular orbitals is a crucial factor for enhancing conductance of molecular wires, the proposed synthesis protocol adopts a new technique to exploit this knowledge, as Tanaka adds "The present study reveals a new strategy to realize molecular wires with an extremely narrow HOMO?LUMO gap via MMM junction formation."

This explanation for the fundamentally different conducting properties of the proposed wires facilitate the strategic development of novel molecular components, which could be the building blocks of future minuscule electronic devices.

Tokyo Institute of Technology

Related Building Blocks Articles from Brightsurf:

Building blocks of language evolved 30-40 million years ago
The capacity for language is built upon our ability to understand combinations of words and the relationships between them, but the evolutionary history of this ability is little understood.

New method to design diamond lattices and other crystals from microscopic building blocks
In a new study appearing in the journal Physical Review Letters, researchers describe a technique for using LEGO®-like elements at the scale of a few billionths of a meter.

New light-based method for faster and 'green' production of building blocks for medicines
Researchers at Eindhoven University of Technology (TU/e), the Netherlands have developed a new method to convert gaseous, low-weight hydrocarbons into more complex molecules by illuminating the hydrocarbons with light in the presence of a suitable catalyst.

Quantifying the building blocks of DNA is now easier thanks to a novel technique
A highly sensitive and easy-to-use technique applicable for tissue samples can be useful, for example, to researchers specialised in mitochondrial diseases and cancer.

Viruses don't have a metabolism; but some have the building blocks for one
'Giant viruses' are many times larger than typical viruses and have more complex genomes.

Antibiotic intercepts building blocks of the bacterial envelope
One of the last arrows in the quiver in the fight against dangerous bacteria is the reserve antibiotic daptomycin.

Scientists have discovered the origins of the building blocks of life
Rutgers researchers have discovered the origins of the protein structures responsible for metabolism: simple molecules that powered early life on Earth and serve as chemical signals that NASA could use to search for life on other planets.

A close-up of Arrokoth reveals how planetary building blocks were constructed
The farthest, most primitive object in the Solar System ever to be visited by a spacecraft - a bi-lobed Kuiper Belt Object known as Arrokoth -- is described in detail in three new reports.

POSTECH developed self-assembled artificial microtubule like LEGO building blocks
Professor Kimoon Kim and his research team identified a new hierarchical self-assembly mechanism

Astronomers reveal interstellar thread of one of life's building blocks
Phosphorus is an essential element for life as we know it.

Read More: Building Blocks News and Building Blocks Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to