Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Oregon approach for 'nanohoops' could energize future devices

13.10.2015

While application is down the road, these tiny organic circular structures could be used in solar cells, light-emitting diodes and medical diagnostics

When Ramesh Jasti began making tiny organic circular structures using carbon atoms, the idea was to improve carbon nanotubes being developed for use in electronics or optical devices. He quickly realized, however, that his technique might also roll solo.


Illustration of a cycloparaphenylene, or nanohoop, that has been doped with nitrogen atoms. Research in the University of Oregon lab of Ramesh Jasti has shown the combination of nitrogen and carbon atoms extends the potential efficiency and capabilities of such structures.

Courtesy of Ramesh Jasti

In a new paper, Jasti and five University of Oregon colleagues show that his nanohoops -- known chemically as cycloparaphenylenes -- can be made using a variety of atoms, not just those from carbon. They envision these circular structures, which efficiently absorb and distribute energy, finding a place in solar cells, organic light-emitting diodes or as new sensors or probes for medicine.

The research, led by Jasti's doctoral student Evan R. Darzi, was described in a paper placed online ahead of print in ACS Central Science, a journal of the American Chemical Society. The paper is a proof-of-principle for the process, which will have to wait for additional research to be completed before the full impact of these new nanohoops can be realized, Jasti said.

These barely one-nanometer nanohoops offer a new class of structures -- sized between those made with long-chained polymers and small, low-weight molecules -- for use in energy or light devices, said Jasti, who was the first scientist to synthesize these types of molecules in 2008 as a postdoctoral fellow at the Molecular Foundry at the Lawrence Berkeley National Laboratory.

"These structures add to the toolbox and provide a new way to make organic electronic materials," Jasti said. "Cyclic compounds can behave like they are hundreds of units long, like polymers, but be only six to eight units around. We show that by adding non-carbon atoms, we are able to move the optical and electronic properties around."

Nanohoops help solve challenges related to materials with controllable band gaps -- the energies that lie between valance and conduction bands and is vital for designing organic semiconductors. Currently long materials such as those based on polymers work best.

"If you can control the band gap, then you can control the color of light that is emitted, for example," Jasti said. "In an electronic device, you also need to match the energy levels to the electrodes. In photovoltaics, the sunlight you want to capture has to match that gap to increase efficiency and enhance the ability to line up various components in optimal ways. These things all rely on the energy levels of the molecules. We found that the smaller we make nanohoops, the smaller the gap."

To prove their approach could work, Darzi synthesized a variety of nanohoops using both carbon and nitrogen atoms to explore their behavior. "What we show is that the charged nitrogen makes a nanohoop an acceptor of electrons, and the other part becomes a donator of electrons," Jasti said.

"The addition of other elements like nitrogen gives us another way to manipulate the energy levels, in addition to the nanohoop size. We've now shown that the nanohoop properties can be easily manipulated and, therefore, these molecules represent a new class of organic semiconductors -- similar to conductive polymers that won the Nobel Prize in 2000," he said. "With nanohoops, you can bind other things in the middle of the hoop, essentially doping them to change properties or perhaps sense an analyte that allows on-off switching."

His early work making nanohoop compounds was carbon-based, with the idea of making them different diameters and then combining them, but his group kept seeing unique and unexpected electronic and optical properties.

Jasti, winner of a National Science Foundation Career Award in 2013, brought his research from Boston University to the UO's Department of Chemistry and Biochemistry in 2014. He said the solar cell research being done by his colleagues in the Materials Science Institute, of which he is a member, was an important factor in his decision to move to the UO.

"We haven't gotten very far into the application of this," he said. "We're looking at that now. What we were able to see is that we can easily manipulate the energy levels of the structure, and now we know how to exchange any atom at any position along the loop. That is the key discovery, and it could be useful for all kinds of semiconductor applications."

###

Co-authors with Darzi and Jasti were: former BU doctoral student Elizabeth S. Hirst, who now is a postdoctoral fellow at the U.S. Army Natick Soldier Research, Development and Engineering Center; UO doctoral student Christopher D. Weber; Lev N. Zakharov, director of X-ray crystallography in the UO's Advanced Materials Characterization in Oregon center; and Mark C. Lonergan, a professor in the Department of Chemistry and Biochemistry.

The NSF (grant CHE-1255219), Department of Energy (DE-SC0012363), Sloan Foundation and Camille and Henry Dreyfus Foundation supported the research.

Source: Ramesh Jasti, associate professor, Department of Chemistry and Biochemistry, 541-346-2508, rjasti@uoregon.edu

Note: The UO is equipped with an on-campus television studio with a point-of-origin Vyvx connection, which provides broadcast-quality video to networks worldwide via fiber optic network. There also is video access to satellite uplink and audio access to an ISDN codec for broadcast-quality radio interviews.

Links:

Jasti faculty page: http://chemistry.uoregon.edu/profile/rjasti/
Department of Chemistry and Biochemistry: http://chemistry.uoregon.edu/
Materials Science Institute: http://materialscience.uoregon.edu/
Paper abstract: http://pubs.acs.org/doi/10.1021/acscentsci.5b00269

Media Contact

Jim Barlow
jebarlow@uoregon.edu
541-346-3481

 @UOregonNews

http://uonews.uoregon.edu

Jim Barlow | EurekAlert!

More articles from Life Sciences:

nachricht The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology

nachricht Colorectal cancer risk factors decrypted
16.07.2018 | Max-Planck-Institut für Stoffwechselforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication

16.07.2018 | Physics and Astronomy

New players, standardization and digitalization for more rail freight transport

16.07.2018 | Transportation and Logistics

Researchers discover natural product that could lead to new class of commercial herbicide

16.07.2018 | Agricultural and Forestry Science

VideoLinks
Science & Research
Overview of more VideoLinks >>>