GaN-based nanowire LEDs beat OLEDs on both flexibility and longevity: Page 2 of 2

May 05, 2017 // By Julien Happich
In a joint research effort at Paris-Sud University, CNRS Orsay (France) and Grenoble's CEA (French Alternative Energies and Atomic Energy Commission), an international team of researchers have fabricated flexible inorganic LEDs based on gallium-nitride semiconductor nanowires.

(a) Schematic illustration of a blue-green
bi-colour flexible NW LED, in which a fully
transparent blue LED is mounted on top of
a green LED. The two LEDs are biased

(b) Electroluminescence spectra (in arbitrary
units) of the bi-colour flexible NW LED.
The blue, green, and red curves show the
emissions from the top layer, bottom layer,
and both layers together (biased simultaneously),

The researchers went on to create a flexible white LED by blending a mixture of yellow phosphors into the polydimethylsiloxane membrane hosting blue emitting NW-LEDs, down-converting the light to a broad spectrum.

Because a NW-LED array can be peeled-off and connected as a single LED sheet, several such sheets can be stacked (embedding NW-LEDs from different compositions), as the researchers demonstrated. Thus they created a flexible bi-colour LED sheet made of a fully transparent flexible blue LED on top of a green LED, each biased separately so as to produce either blue or green light, or a mix of the two.

Photographs of the blue (top), green (middle),
and white (bottom) flexible LEDs operating under
different bending conditions.


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