A team of researchers about whom we’ve been talking about more then two years ago, from the Idaho National Laboratory in Idaho Falls, has made advances in the study of a special kind of solar cells that can harvest the solar power even at night, in the absence of visible light.
When the Sun’s heat warms everything during the day, the energy is not lost, but stored as heat and released as infrared light during those hot summer nights.
One issue that had been stopping researchers to practically implement this kind of infrared-harvesting solar cells has been the lack of conversion technology from the high frequencies of infrared light into alternating electricity.
The Idaho team has experimented gold nanoantennas for a long time now. Their first forecasts about the efficiency of such a system had been very optimistic, about 92 percent. Nowadays, they recalculated and reached the conclusion that a complete infrared solar cell system would go up to 46 percent (while most modern solar cells have around 25 percent). Under ideal lab conditions, though, the efficiency raises up to 84 percent.
Steven Novack, one of the first to experiment with nanoantennas, has recently devised a technique for manufacturing nanoantennas fit to different light wavelengths. Although currently they are not small enough to reach the wavelengths of the infrared spectrum, Novack says he and his team can tune them to work with mid and near-infrared frequencies in the future.
Other scientists from the University of Colorado in Boulder have created new diodes that can handle high optical frequencies. Blended with Novack’s nanoantennas, these could transform light into electricity during the next months. Both teams say that their discoveries could change the way solar cells are made, and hope to make them truly efficient, not just expensive toys.
[via new scientist]