Nav: Home

Plot twist: Straightening single-molecule conductors improves their performance

June 11, 2019

Osaka, Japan - A team at Osaka University has created single-molecule nanowires, complete with an insulation layer, up to 10 nanometers in length. When they measured the electrical properties of these nanowires, the researchers found that forcing the ribbon-like chains to be flat significantly improved their conductivity compared with a twisted conformation. The findings may allow for a new generation of inexpensive high-tech devices, including smartphone screens and photovoltaics.

Carbon-based polymers, which are long molecular chains made of repeating units, can be found everywhere, from the rubber in the soles of your shoes to the proteins that make up your body. We used to think that these molecules could not conduct electricity, but that all changed with the discovery of conducting polymers. These are a small subset of carbon-based molecules that can act like tiny wires owing to their alternating single and double chemical bonds, also called conjugated bonds. Since carbon-based conductors are much easier and cheaper to make and customize than conventional electronics, they have seen rapid adoption in OLED TVs, iPhone screens, and solar panels, while drastically reducing their cost.

Now, researchers at Osaka University have synthesized chains of oligothiophene of various lengths, with up to 24 repeat units. This means that single nanowires could be up to 10 nanometers in length. Insulation of the wires was needed to avoid interwire currents, so that the intrinsic conductivity of a single molecule could be measured accurately. On the basis of the rules of quantum mechanics, electrons in molecules behave more like spread-out waves than localized particles. The overlapping bonds in oligothiophene allow electrons to be entirely spread out over the polymer backbone, so they can easily transverse the molecule to create an electrical current.

This charge transport can occur is two very different ways. "Over short distances, electrons rely on their wave-like nature to 'tunnel' directly through barriers, but over long distances, they hop from site to site to reach their destination," first author Dr. Yutaka Ie explained. The team at Osaka University found that changing the oligothiophene chain from twisted to flat led to much greater overlap of the conjugated backbone of oligothiophene, which in turn meant a larger overall conductivity. As a result, the crossover from tunneling to hopping conduction took place with flat chains at shorter chain lengths, compared with those with the twisted conformation.

The researchers believe that this work can open a whole new world of devices. "This study demonstrates that our insulated nanowires have the potential to be used in novel 'single-molecule' electronics," lead author Dr. Yoshio Aso said. The work is published in The Journal of Physical Chemistry Letters as "Highly Planar and Completely Insulated Oligothiophenes: Effects of π-Conjugation on Hopping Charge Transport." (DOI: 10.1021/acs.jpclett.9b00747)
-end-
About Osaka University

Osaka University was founded in 1931 as one of the seven imperial universities of Japan and now has expanded to one of Japan's leading comprehensive universities. The University has now embarked on open research revolution from a position as Japan's most innovative university and among the most innovative institutions in the world according to Reuters 2015 Top 100 Innovative Universities and the Nature Index Innovation 2017. The university's ability to innovate from the stage of fundamental research through the creation of useful technology with economic impact stems from its broad disciplinary spectrum. Website: https://resou.osaka-u.ac.jp/en/top

Osaka University

Related Nanowires Articles:

Nanowires, the future of electronics
The current demand for small-sized electronic devices is calling for fresh approaches in their design.
Improving silver nanowires for FTCEs with flash light interactions
A Korean research team led by Professor Keon Jae Lee of the Materials Science and Engineering Department at KAIST and Dr.
UC researchers use gold coating to control luminescence of nanowires
In electronics, the race for smaller is huge. Physicists at the University of Cincinnati are working to harness the power of nanowires, microscopic wires that have the potential to improve solar cells or revolutionize fiber optics.
Obtaining of silicon nanowires becomes eco-friendly
Scientists from the Faculty of Physics, the Lomonosov Moscow State University have devised a technique of silicon nanowires synthesis.
Nanowires as sensors in new type of atomic force microscope
A new type of atomic force microscope (AFM) uses nanowires as tiny sensors.
Tiny crystals and nanowires could join forces to split water
Scientists are pursuing a tiny solution for harnessing one of the world's most abundant sources of clean energy: water.
A versatile method to pattern functionalized nanowires
A team of researchers from Hokkaido University has developed a versatile method to pattern the structure of 'nanowires,' providing a new tool for the development of novel nanodevices.
Newly discovered organic nanowires leave manmade technologies in their dust
A microbial protein fiber discovered by a Michigan State University scientist transports charges at rates high enough to be applied in manmade nanotechnologies.
New research shows how nanowires can be formed
In an article published in Nature today, researchers at Lund University in Sweden show how different arrangements of atoms can be combined into nanowires as they grow.
New type of nanowires, built with natural gas heating
A new simple, cost-effective approach that may open up an effective way to make other metallic/semiconducting nanomaterials.

Related Nanowires Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Moving Forward
When the life you've built slips out of your grasp, you're often told it's best to move on. But is that true? Instead of forgetting the past, TED speakers describe how we can move forward with it. Guests include writers Nora McInerny and Suleika Jaouad, and human rights advocate Lindy Lou Isonhood.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...