Converting sunlight into electricity is not economically attractive because of the high cost of solar cells, but a recent, purely optical approach to improving luminescent solar concentrators (LSCs) may ease the problem, according to researchers at Argonne National Laboratories and Penn State. Using concentrated sunlight reduces the cost of solar power by requiring fewer solar cells to generate a given amount of electricity. LSCs concentrate light by absorbing and re-emiting it at lower frequency within the confines of a transparent slab of material. They can not only collect direct sunlight, but on cloudy days, can collect diffuse light as well. The material then guides the light to the slab's edges, where photovoltaic cells convert the energy to electricity.