Light up with a jellyfish

Researchers from the University of South Carolina have enlisted the help of jellyfish in their efforts to develop better light-emitting diodes (LEDs).

The Pacific Ocean jellyfish is said to produce the kind of light that researchers try to coax from crystalline semiconductors such as indium phosphide or gallium arsenide.

Jellyfish accomplish this with aplomb because its light comes from green fluorescent protein (GFP), which collects the energy produced in a cellular chemical reaction and emits it as green light from a molecular package called chromophore.

Inspired by the Pacific Ocean jellyfish’s green glow, Mark Thompson of the University of Southern California and his colleagues synthesised chromophore-like molecules, which they then seeded onto a matrix of organic molecules in an organic LED (OLED).

These devices are built form a variety of different molecular and polymeric materials, which serve as electron and hole carriers, sites of recombination and luminescent zones.

They believed the chromophore-like molecules would function as ‘dopants,’ converting energy captured from the matrix into light. After adjusting the molecular structures, the team produced both green and orange OLEDs.

Researchers are keen to develop such OLEDs for flat-screen, portable computer displays because they would be simpler and cheaper to make than their non-organic counterparts.

Although not so efficient as existing devices, the chromophore-based model should improve with further work.

Thompson has spent a great deal of time focussing on the colour tuning of these devices in some detail. With the use of both fluorescent and phosphorescent dopants he has tuned the OLED colour form blue to red with efficiency as high as 10%.

‘There are an enormous variety of fluorescent organisms,’ noted the team. ‘Other materials can be prepared using the insight provided by naturally occurring systems, which may be useful in electronic and optoelectronic applications.’