Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UGA scientists invent long-lasting, near infrared-emitting material

21.11.2011
Implications for medical diagnostics, security and solar energy

Materials that emit visible light after being exposed to sunlight are commonplace and can be found in everything from emergency signage to glow-in-the-dark stickers. But until now, scientists have had little success creating materials that emit light in the near-infrared range, a portion of the spectrum that only can be seen with the aid of night vision devices.

In a paper just published in the early online edition of the journal Nature Materials, however, University of Georgia scientists describe a new material that emits a long-lasting, near-infrared glow after a single minute of exposure to sunlight. Lead author Zhengwei Pan, associate professor of physics and engineering in the Franklin College of Arts and Sciences and the Faculty of Engineering, said the material has the potential to revolutionize medical diagnostics, give the military and law enforcement agencies a "secret" source of illumination and provide the foundation for highly efficient solar cells.

"When you bring the material anywhere outside of a building, one minute of exposure to light can create a 360-hour release of near-infrared light," Pan said. "It can be activated by indoor fluorescent lighting as well, and it has many possible applications."

The material can be fabricated into nanoparticles that bind to cancer cells, for example, and doctors could visualize the location of small metastases that otherwise might go undetected. For military and law enforcement use, the material can be fashioned into ceramic discs that serve as a source of illumination that only those wearing night vision goggles can see. Similarly, the material can be turned into a powder and mixed into a paint whose luminescence is only visible to a select few.

The starting point for Pan's material is the trivalent chromium ion, a well-known emitter of near-infrared light. When exposed to light, its electrons at ground state quickly move to a higher energy state. As the electrons return to the ground state, energy is released as near-infrared light. The period of light emission is generally short, typically on the order of a few milliseconds. The innovation in Pan's material, which uses matrix of zinc and gallogermanate to host the trivalent chromium ions, is that its chemical structure creates a labyrinth of "traps" that capture excitation energy and store it for an extended period. As the stored energy is thermally released back to the chromium ions at room temperature, the compound persistently emits near-infrared light over period of up to two weeks.

In a process that Pan likens to perfecting a recipe, he and postdoctoral researcher Feng Liu and doctoral student Yi-Ying Lu spent three years developing the material. Initial versions emitted light for minutes, but through modifications to the chemical ingredients and the preparation—just the right amounts of sintering temperature and time—they were able to increase the afterglow from minutes to days and, ultimately, weeks.

"Even now, we don't think we've found the best compound," Pan said. "We will continuously tune the parameters so that we may find a much better one."

The researchers spent an additional year testing the material—indoors and out, as well as on sunny days, cloudy days and rainy days—to prove its versatility. They placed it in freshwater, saltwater and even a corrosive bleach solution for three months and found no decrease in performance.

In addition to exploring biomedical applications, Pan's team aims to use it to collect, store and convert solar energy. "This material has an extraordinary ability to capture and store energy," Pan said, "so this means that it is a good candidate for making solar cells significantly more efficient."

The U.S. Office of Naval Research, the National Science Foundation, the American Chemical Society Petroleum Research Fund and the UGA Research Foundation supported the research.

Zhengwei Pan | EurekAlert!
Further information:
http://www.uga.edu

More articles from Materials Sciences:

nachricht Shock-dissipating fractal cubes could forge high-tech armor
08.07.2020 | DOE/Los Alamos National Laboratory

nachricht Atomic 'Swiss army knife' precisely measures materials for quantum computers
08.07.2020 | National Institute of Standards and Technology (NIST)

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

Im Focus: ILA Goes Digital – Automation & Production Technology for Adaptable Aircraft Production

Live event – July 1, 2020 - 11:00 to 11:45 (CET)
"Automation in Aerospace Industry @ Fraunhofer IFAM"

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM l Stade is presenting its forward-looking R&D portfolio for the first time at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

 
Latest News

Shock-dissipating fractal cubes could forge high-tech armor

08.07.2020 | Materials Sciences

Scientists use nanoparticle-delivered gene therapy to inhibit blinding eye disease in rodents

08.07.2020 | Health and Medicine

'Growing' active sites on quantum dots for robust H2 photogeneration

08.07.2020 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>