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Tech breakthrough could give us more efficient LEDs and invisibility cloaks, too

university michigan invisibility cloak nanoparticles could spur better leds cloaks chamber orig 20170719
Joseph Xu, Michigan Engineering
Researchers at the University of Michigan want to make your LED lights 50 percent more efficient — and develop Harry Potter-style invisibility cloaks in the process.

In a new study described in the Journal of Applied Physics, the researchers describe the development of a new technique that involves “peppering” nanoparticles into semiconductors. This is reportedly a world-first when it comes to being able to cheaply grow metal nanoparticles on and below the surface of semiconductors: Something that means fewer semiconductors would have to be used in finished products. (For those keeping track at home, fewer semiconductors mean cheaper products!)

These metal nanoparticles can help increase LED efficiency by acting as miniature antennas, which redirect the electricity that runs through a semiconductor, resulting in more of it being turned into light. In addition, the metal nanoparticles help reflect light out of the device, rather than it being trapped inside and therefore wasted.

While adding nanoparticles to increase the efficiency of LEDs is not necessarily new, previous attempts to achieve this have not been practical for mass manufacturing. One reason is that they relied on expensive metals like silver, gold or platinum. In this project, the investigators were able to change by getting their nanoscale particles to perform the same role as gold and platinum flecks in previous work.

The really exciting potential development, however, is the possibility of invisibility cloaking devices. The theory behind this is a phenomenon called “reverse refraction,” which involves bending light backward in a way that does not happen in nature. The hypothesis of the researchers is that careful sizing and spacing of an array of its nanoparticles would be able to control specific wavelengths of light.

“For invisibility cloaking, we need to both transmit and manipulate light in very precise ways, and that’s very difficult today,” said Rachel Goldman, professor of materials science, engineering and physics. “We believe that this process could give us the level of control we need to make it work.”

We are still pretty far away from all being able to don our own invisibility capes and creep around Hogwarts, of course, but this work certainly takes us one step closer.

It’s worth noting that this far from the only attempt to develop invisibility capes we have reported on in recent years. But, hey, none of the others promise to give you longer-lasting LED lights while you’re waiting, do they?

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