Friday, November 15, 2013

Solar bonanza

A new solar cell material has properties that might lead to solar cells more than twice as efficient as the best on the market today. The material—a modified form of a class of compounds called perovskites, promises to be a good choice though not experimentally used.

Researchers are making new perovskites using combinations of elements and molecules not seen in nature; many researchers see the materials as the next great hope for making solar power cheap enough to compete with fossil fuels. Perovskite-based solar cells have been improving at a remarkable pace. It took a decade or more for the major solar cell materials used today—silicon and cadmium telluride—to reach efficiency levels that have been demonstrated with perovskites in just four years.

The perovskite material described in the latest Nature has properties that could lead to solar cells that can convert over half of the energy in sunlight directly into electricity according to the center for energy innovation at the University of Pennsylvania.

That’s more than twice as efficient as conventional solar cells. Such high efficiency would cut in half the number of solar cells needed to produce a given amount of power. Besides reducing the cost of solar panels, this would greatly reduce installation costs, which now account for most of the cost of a new solar system.

Unlike conventional solar cell materials, the new material doesn’t require an electric field to produce an electrical current. This reduces the amount of material needed and produces higher voltages, which can help increase power output. While other materials have been shown to produce current without the aid of an electric field, the new material is the first to also respond well to visible light, making it relevant for solar cells.

The researchers also showed that it is relatively easy to modify the material so that it efficiently converts different wavelengths of light into electricity. It could be possible to form a solar cell with different layers, each designed for a specific part of the solar spectrum, something that could greatly improve efficiency compared to conventional solar cells.

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