80% efficient solar cells from nanotechnology

Cool. This could solve a lot of problems if it can be made practical. [Link]

Because of their size, the nanoantennas absorb energy in the infrared part of the spectrum, just outside the range of what is visible to the eye. The sun radiates a lot of infrared energy, some of which is soaked up by the earth and later released as radiation for hours after sunset. Nanoantennas can take in energy from both sunlight and the earth's heat, with higher efficiency than conventional solar cells.

"I think these antennas really have the potential to replace traditional solar panels," says physicist Steven Novack, who spoke about the technology in November at the National Nano Engineering Conference in Boston.

The miniscule circuits absorb energy just like the antenna on your television or in your cell phone. All antennas work by resonance, the same self-reinforcing physical phenomenon that allows a high note to shatter glass. Radio and television antennas must be large because of the wavelength of energy they need to pick up. In theory, making antennas that can absorb electromagnetic radiation closer to what we can see is simple: just engineer a smaller antenna.

But finding an efficient way to stamp out arrays of atom-scale spirals took a number of years. "It's not that this concept is new," Novack says, "but the boom in nanotechnology is what has really made this possible." The INL team envisions the antennas might one day be produced like foil or plastic wrap on roll-to-roll machinery.

The team estimates individual nanoantennas can absorb close to 80 percent of the available energy. The circuits themselves can be made of a number of different conducting metals, and the nanoantennas can be printed on thin, flexible materials like polyethylene, a plastic that's commonly used in bags and plastic wrap. In fact, the team first printed antennas on plastic bags used to deliver the Wall Street Journal, because they had just the right thickness.