US scientists build thinnest-known LEDs

Scientists have built the thinnest-known LEDs that are 10,000 times smaller than the thickness of a human hair and can be used as a source of light energy in electronics.
Most modern electronics, from flat-screen TVs and smartphones to wearable technologies and computer monitors, use tiny light-emitting diodes, or LEDs.
These LEDs are based off of semiconductors that emit light with the movement of electrons. As devices get smaller and faster, there is more demand for such semiconductors that are tinier, stronger and more energy efficient.
The LED developed by the University of Washington is based off of two-dimensional, flexible semiconductors, making it possible to stack or use in much smaller and more diverse applications than current technology allows.

"We are able to make the thinnest-possible LEDs, only three atoms thick yet mechanically strong. Such thin and foldable LEDs are critical for future portable and integrated electronic devices," said Xiaodong Xu, a UW assistant professor in materials science and engineering and in physics.
Most consumer electronics use three-dimensional LEDs, but these are 10 to 20 times thicker than the LEDs being developed by the UW.

"These are 10,000 times smaller than the thickness of a human hair, yet the light they emit can be seen by standard measurement equipment," said Jason Ross, a UW materials science and engineering graduate student.

"This is a huge leap of miniaturisation of technology, and because it's a semiconductor, you can do almost everything with it that is possible with existing, three-dimensional silicon technologies," Ross said.
The UW's LED is made from flat sheets of the molecular semiconductor known as tungsten diselenide, a member of a group of two-dimensional materials that have been recently identified as the thinnest-known semiconductors.
Researchers use regular adhesive tape to extract a single sheet of this material from thick, layered pieces in a method inspired by the 2010 Nobel Prize in Physics awarded to the University of Manchester for isolating one-atom-thick flakes of carbon, called graphene, from a piece of graphite.

In addition to light-emitting applications, this technology could open doors for using light as interconnects to run nano-scale computer chips instead of standard devices that operate off the movement of electrons, or electricity.
The latter process creates a lot of heat and wastes power, whereas sending light through a chip to achieve the same purpose would be highly efficient, researchers said.
The details of the study are published in the journal Nature Nanotechnology.