Solar cells can absorb and emit light

In a development that could lead to cheaper lasers, researchers have discovered that perovskite solar cells can emit as well as absorb light.

By sandwiching a thin layer of lead halide perovskite between two mirrors, researchers from Cambridge's Cavendish Laboratory produced an optically driven laser that effectively re-emitted 70% of absorbed light.

"This first demonstration of lasing in these cheap solution-processed semiconductors opens up a range of new applications," said Dr Felix Deschler, whoe led the research. "Our findings demonstrate potential uses for this material in telecommunications and for light emitting devices."

While most commercial solar cell materials need expensive processing before they show good luminescence, the new materials work well even when simply prepared as thin films using cheap scalable solution processing.

The researchers found that upon light absorption in the perovskite, two charges (electron and hole) form very quickly – within 1ps – but then take anywhere up to a few microseconds to recombine.

This is long enough for chemical defects to have ceased the light emission in most other semiconductors, such as silicon or gallium arsenide.

"These long carrier lifetimes, together with exceptionally high luminescence, are unprecedented in such simply prepared inorganic semiconductors," said Oxford University's Dr Sam Stranks, who helped with the research. "This has great implications for improvements in solar cell efficiency."

Sustainable Fusion Reactor

Nuclear fission (the process by which nuclear power plants produce energy) is much easier to control than nuclear fusion (the process by which the sun burns, and nuclear weapons work). Small nuclear fusion reactors have been built, but a large-scale, sustainable fusion reactor has yet to be attempted—until now. A consortium of seven member bodies (the US, EU, Russia, China, Japan, South Korea, and India) has chosen a location in France to build the world first. And while even its champions concede it could be decades before it’s dispensing energy, nuclear fusion is cleaner and yields three to four times more power than fusion.
The project is called ITER, for International Thermonuclear Experimental Reactor, and it is the second-largest cooperative international scientific endeavor (ranking behind only the Space Station). It will use a donut-shaped magnetic field to contain gases that will reach temperatures comparable to those at the core of the sun, in excess of 150 million degree C

(270 million F), and will produce 10 times more power than it consumes.

Paper-Thin, Flexible Computers and Phones

In early 2013, consumer electronics shows debuted a prototype by European firm Plastic Logic of a product called the Paper tab. That would be a portmanteau of “paper” and “tablet” and it is pretty much what it sounds like: a fully functional, touch screen tablet computer that is not only as thin as a sheet of paper, but as flexible as one too, and possesses the same reflective qualities. The company envisions such machines being ubiquitous within five to 10 years, as they could be inexpensive and interactive. A consumer could have several lying around, multi-tasking with different media all in service of one project.
A joint project between two American and Canadian universities has been creatively dubbed the Paper phone. Queens University director Dr. Roel Vertegaal has largely the same vision of the project. “This is the future,” he says. “Everything is going to look and feel like this within five years.” The machine is the size of a regular smartphone, with a 9.4-centimeter (3.7 in) display, but again, paper-thin and flexible. Users can give the phone commands by using “bend gestures.” It consumes no power when not in use and is considerably harder to damage than an ordinary phone.

New lens design improves kidney stone treatment

Duke Univ. engineers have devised a way to improve the efficiency of lithotripsy—the demolition of kidney stones using focused shock waves. After decades of research, all it took was cutting a groove near the perimeter of the shock wave-focusing lens and changing its curvature.

NIST chips help South Pole telescope find direct evidence of universe origin

Earlier this week, a team of U.S. cosmologists using the BICEP2 telescope at the South Pole said they have discovered the first direct evidence of the rapid inflation of the universe at the dawn of time. The finding was made possible, in part, by superconducting quantum interference devices (SQUIDs) designed at NIST.

Researchers devise stretchable antenna for wearable health monitoring

Researchers from North Carolina State Univ. have developed a new, stretchable antenna that can be incorporated into wearable technologies, such as health monitoring devices. The researchers wanted to develop an antenna that could be stretched, rolled or twisted and always return to its original shape, because wearable systems can be subject to a variety of stresses as patients move around.

Source-gated transistor could pave the way for flexible gadgets

Existing transistors act as electronic switches, altering current flow through a semiconductor by controlling the bias voltage across the channel region. A new electronic component, called a source-gated transistor, has been developed in the U.K. and exploits physical effects such as the Schottky barriers at metal-semiconductor contacts. This innovation could improve the reliability of future digital circuits used within flexible gadgets.