U. of Georgia researchers create near-IR phosphor that emits for weeks

persistent_IR_phosphor
Zhengwei Pan and Feng Liu stand in a darkened room lit only by ceramic discs containing a persistent near-IR phosphor. The phosphorescent material was also mixed into the paint that was used to create the University of Georgia logo behind them. (Imaging parameters: auto, ISO 200, 3-4 seconds of exposure time using a night-vision monocular.) Image: Zhengwei Pan/UGA



Athens, GA--While persistent phosphors (glow-in-the-dark materials) for the visible region are everywhere, persistent IR phosphors have been difficult to develop. Now, a group at the University of Georgia has created a near-IR phosphor that has an afterglow of up to two weeks after a one-minute exposure to sunlight.1 The material can be made into paints, all-weather ceramic disks, or even into nanoparticles that bind to cancer cells.

The researchers created a series of chromium-doped zinc gallogermanate phosphors that exhibit strong emission at somewhere between 650 to 1000 nm, with the peak wavelength determined by composition.

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

The time period of light emission for the trivalent chromium ion used in the emitter is normally short, typically on the order of a few milliseconds. The innovation in Pan's material 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-IR light.

Pan and researchers Feng Liu and Yi-Ying Lu spent three years developing the material. Initial versions emitted light for minutes, but the researchers extended this time to days, and finally to weeks. "Even now, we don't think we've found the best compound," Pan says. "We will continuously tune the parameters so that we may find a much better one."

The researchers placed the material in fresh water, salt water, 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 says, "so this means that it is a good candidate for making solar cells significantly more efficient."


REFERENCE:

1. Zhengwei Pan et al., Nature Materials, published online 20 November 2011; doi:10.1038/nmat3173.





Get All the Laser Focus World News Delivered to Your Inbox

Subscribe to Laser Focus World Magazine or email newsletter today at no cost and receive the latest news and information.

 Subscribe Now

Most Popular Articles

Webcasts

Mid-infrared lasers in remote chemical sensing – from stand-off detection to atmospheric sounding

In this webcast, Gerard Wysocki of MIRTHE will discuss the unique remote-sensing capabilities enabled by modern mid-infrared (mid-IR) lasers and novel spectr...

Femtosecond Lasers – Getting the Photons to the Work Area

Ultrashort-pulse lasers, both picosecond and femtosecond, are now available from a large number of manufacturers, with new players entering the field at a ra...
White Papers

Degradation studies of a VECSEL gain structure using a stable green pump laser

The degradation of the gain structure of a red-emitting Optically Pumped Semiconductor (OPS) Vert...

Tailored bar concepts for 10 mm-mrad fiber coupled modules scalable to kW-class direct diode lasers

In this paper, laser modules based on newly developed tailored bars are presented. The modules al...

Wavelength stabilized multi-kW diode laser systems

Wavelength stabilization of high-power diode laser systems is an important means to increase the ...
Technical Digests

Fiber for Fiber Lasers

The development of higher-power and higher-energy fiber lasers has benefited from many advances i...

SCANNERS FOR MATERIALS PROCESSING: Serving demanding applications

Galvanometer-based scanners are an essential component in laser-based materials-processing system...

Click here to have your products listed in the Laser Focus World Buyers Guide.

PRESS RELEASES

Social Activity
  •  
  •  
  •  
  •  
Copyright © 2007-2014. PennWell Corporation, Tulsa, OK. All Rights Reserved. PRIVACY POLICY | TERMS AND CONDITIONS