In the laboratories of MIT put nanotechnology in the service of photovoltaic created a fiber capable of concentrating and multiplying by 100 the sun's energy. Will be the star of the future of photovoltaics? The promises are enticing but it is still early to tell.
"solar funnels," or antennas made of nanotubes, able to concentrate and increase the sun's energy and promise to give rise to new low-cost cells. Could come from nanotechnology developments in the photovoltaic panels and the future could produce the same amount of energy with a hundredth the size of current ones. In the laboratories of the Massachusetts Institute of Technology (MIT) is working on a new very interesting material for the energy from the sun, presented recently in a study published in Nature Materials.
innovation study not so recently, because a few years ago is the subject of work by some laboratories, but now is slowly taking more concrete. Using carbon nanotubes, or hollow tubes made of carbon atoms, the chemical engineers at MIT have found a way of creating antennas capable of concentrating solar energy multiplying by 100 compared to the normal flow involving both a solar cell. "Rather than having the entire roof covered with solar cells you can have some small spots with tiny cells equipped with antennas that direct photons," said Michael Strano, a researcher involved in the project called "solar funnel", that is, precisely, "solar funnel ".
We know that solar panels work by converting photons into electrical current, ie the light energy from the sun. The "nano funnels" MIT would only increase exponentially the number of photons that the cell can capture. Nothing to do with concentrating solar power as we know, nothing to do with lenses and mirrors, but here everything is played on a scale of micrometers, or millionths of a meter. The antenna, a result of advances in nanotechnology, is a fiber length of about 10 micrometers thick and 4 contains about 30 million carbon nanotubes (see above microscope image, courtesy MIT).
The peculiarity that makes this "funnel" to focus the photons nanotechnology is being made of two layers of nanotubes, each with different electrical properties, specifically different "bandgap", ie gaps in the conduction band. The nanotube sheet internal antenna has a smaller bandgap than that of the outer layer: this means that excitons (the result of the interaction between the electrons and the bandgap) are being routed to the inside antenna. When light hits the material, therefore, all excitons flowing toward the center of the fiber, where they are concentrated.
The material can also be used in other applications, such as night vision goggles or scopes. But the most important next step will be integrated into a photovoltaic device, the antenna built around a semiconductor material. For now, the fibers disperse 13% of light energy absorbed, but the aim is to reduce this loss to 1%. The efficiency of the device then depend on that of the semiconductor. Of course, with a concentration factor of 100, the promises are enticing.
nanotubes solar cells could, therefore, become low-cost alternative to traditional? According to Strange, yes "in the near future, carbon nanotubes will be sold at pennies per ounce, like polymers," and continues: "The addition (of the nano-antennas, ed) cells would result in a negligible increase in costs compared the cost of production of the cell itself. "
However, some minor problems to be solved. For example, says Michael Arnold, a professor of materials science at the University of Wisconsin at Madison, “bisogna investigare come gli eccitoni nello strato interno (dell'antenna, ndr) potranno essere raccolti e trasformati in energia elettrica”. Insomma, stiamo parlando di tecnologie interessanti, ma per il momento ancora lontane dal poter influire concretamente sul settore del fotovoltaico. Abbiamo cioè ancora un po' di tempo per vedere se le promesse degli “imbuti solari” verranno mantenute
Fonte QualEnergia
0 comments:
Post a Comment