Could a simple shape change light the way to better OLEDs? Image Credits: Photos.com

A new organic molecule has been created that could vastly alter the organic light emitting diodes (OLEDs) used in modern electronic devices.

These structures, likened to rotelle pasta, are more efficient than the traditional ‘spaghetti-like’ chain polymers currently used in OLEDs. The reason for this is that in current OLEDs, the light is polarised by the chain polymers and hence a significant amount of light gets trapped within the LED.The pi-conjugated spoked-wheel macrocycle, or ‘wagon wheel’ molecule, has been created by physicists from the University of Utah and their findings have been published recently in the journal Nature Chemistry.

By contrast, the circular structure of the new molecule ‘scrambles’ the polarisation of the light, allowing light energy to be emitted in all directions at random.

John Lupton, lead author of this study, explains this principle in more depth below:

"The rotelle – technically called oligomers – are basically wrapped-up polymers. They all have the same shape, but they do not emit polarized light because they are round. They generate waves that vibrate in all directions. The light doesn't have a fixed polarization; it doesn't vibrate in a fixed direction. It always can get out."

Images of molecules for light-emitting diodes on the left are compared with similar shaped pasta on the right. The upper left electron microscope image shows spaghetti-shaped organic polymers now used for organic light-emitting diodes, or OLEDs. The lower left image shows new molecules -- created by scientists at the University of Utah and two German universities -- that are shaped like wagon-wheel or rotelle pasta and emit light more efficiently than the spaghetti-shape polymers. Image Credit: Molecule images by Stefan Jester, University of Bonn. Pasta images courtesy Wikimedia Commons.

OLEDs are currently widely used in a myriad of electronic devices, from smart phones to TV screens.

Utilising the new molecules would lead to OLEDs that use far less electricity, meaning potential benefits such as longer phone battery life.

A further benefit of the wagon wheel molecules is that they can trap other molecules, meaning they could be utilised in biological sensors and solar panels.

Though Lupton acknowledges that the commercial implementation of such molecules is currently a long way off, he notes in a recent press release that "in principle, we should be able to double the efficiency of getting the light out".

Sources and Further Reading