This graphical representation shows the layers of the 2-D LED and how it emits light. (Image courtesy University of Washington)
SEATTLE—University of Washington scientists have built the thinnest-known LED that can be used as a source of light energy in electronics, thanks in part to a breakthrough by researchers at Oak Ridge National Laboratory and University of Tennessee in Knoxville.
The LED 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,” said Xiaodong Xu, a UW assistant professor in materials science and engineering and in physics. “Such thin and foldable LEDs are critical for future portable and integrated electronic devices.”
Most consumer electronics use three-dimensional LEDs, but they are up to 20 times thicker than the LEDs being developed.
“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 who co-authored the report. “This is a huge leap of miniaturization of technology, and because it’s a semiconductor, you can do almost everything with it that is possible with existing, three-dimensional silicon technologies.”
The new 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.
Nirmal Ghimire, Jiaqiang Yan, and D.G. Mandrus of UT’s Department of Materials Science and Engineering and ORNL were instrumental in the creation of that semiconductor, with the crystals that made it possible being grown in the Science and Engineering Research Facility on UT’s campus thanks to a grant from the U.S. Department of Energy.
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 electricity, a far more efficient method of power.
“A promising solution is to replace the electrical interconnect with optical ones, which will maintain the high bandwidth but consume less energy,” Xu said. “Our work makes it possible to make highly integrated and energy-efficient devices in areas such as lighting, optical communication and nano lasers.”
Other co-authors include Aaron Jones and David Cobden of UW; Philip Klement of Justus Liebig University in Germany; Takashi Taniguchi, Kenji Watanabe, and Kenji Kitamura of the National Institute for Materials Science in Japan; and Wang Yao of the University of Hong Kong.
Additional funding for the research came from the U.S. Department of Energy Office of Science, the Research Grant Council of Hong Kong, the University Grant Committee of Hong Kong and the Croucher Foundation. Ross is supported by a National Science Foundation graduate fellowship.
Read the University of Washington story here.
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