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Pasta shape provides better LED

'Rotelle' molecules depolarise light and are more efficient than 'spaghetti'

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One problem in developing more efficient organic LED light bulbs and displays for TVs and phones is that much of the light is polarized in one direction and thus trapped within the light-emitting diode, or LED. University of Utah physicists believe they have solved the problem by creating a new organic molecule that is shaped like rotelle – wagon-wheel pasta – rather than spaghetti.

The rotelle-shaped molecule – known as a "pi-conjugated spoked-wheel macrocycle" – acts the opposite of polarizing sunglasses, which screen out glare reflected off water and other surfaces and allow only direct sunlight to enter the eyes.

The new study showed wagon-wheel molecules emit light randomly in all directions – a necessary feature for a more efficient OLED, or organic LED. Existing OLEDs now in some smart phones and TVs use spaghetti-shaped polymers – chains of repeating molecular units – that emit only polarized light.

"This work shows it is possible to scramble the polarization of light from OLEDs and thereby build displays where light doesn't get trapped inside the OLED," says University of Utah physicist John Lupton, lead author of a study of the spoked-wheel-shaped molecules published online Sunday, Sept. 29 in the journal Nature Chemistry.

"We made a molecule that is perfectly symmetrical, and that makes the light it generates perfectly random," he...

The full text of this article can be purchased from Informit.