UC Berkeley engineers built an invisible LED that’s just three atoms thick

By Jean-Jacques
DeLisle, contributing writer

 

 

A
new light emitting device has been developed in the laboratory of Ali Javey,
professor of electrical engineering and computer sciences at Berkeley and it
may have a very bright future. The new device is three atoms thick and can be made smaller than a human
hair
. Funded by the National Science Foundation and
the Department of Energy, the advancement was published in Nature Communications on March 26. A
previously published work by the Ali Javey lab in 2015 showed how different
semiconductors were capable of emitting light but they were unable to create a
functioning light emitting device. 

The
atomically thin light emitting device opens the possibility for invisible
displays. Image source:
Berkeley.

 

The
new report published in Nature Communications shows proof of concept for a new
type of LED which can overcome some of the fundamental problems with LED
technology today. In traditional LEDs, an electrical current is passed through
the light emitting diode and creates light using a DC current. These are
efficient but not as scalable as modern tech companies would like. The new LEDs
are much smaller than their predecessors, and according to its creators, it can
even be made invisible.

 

“The
materials are so thin and flexible that the device can be made transparent and
can conform to curved surfaces,” said Der-Hsien Lien, a postdoctoral
fellow at UC Berkeley, in a press release. Der-Hsien Lien is a co-first author
along with Matin Amani and Sujay Desai, doctoral students in the Department of
Electrical Engineering and Computer Sciences at Berkeley.

 

The
new LEDs function on an AC field, unlike previous LED technology that required
current injection. The field results from an AC voltage connection to the LED
monolayer and to an insulator underneath the monolayer, so there is only one
point of contact to the LED itself, rather than the two points that are
required for typical LEDs. This cuts down on material cost and allows the
devices to be miniaturized. The Devices work by laying the semiconductor
monolayer on an insulator and placing electrodes on the monolayer and
underneath the insulator. In this arrangement researchers could apply an AC
signal across the insulator and excite the semiconductor, creating light.

 

The
applications for this new technology are wide-ranging. Powerful lights could be
invisibly installed for security systems. Tiny transparent displays could
disappear and reappear as they are needed or windows on skyscrapers that softly
glow at night, reducing energy costs. The devices could even be embedded under
the skin to create glowing tattoos. The technology shows a lot of promise,
though it is still in its fledgling stages. “A lot of work remains to be done
and a number of challenges need to be overcome to further advance the
technology for practical applications,” Javey said. “However, this is one step
forward by presenting a device architecture for easy injection of both charges
into monolayer semiconductors.”