Solar cells today are made from expensive materials such as crystalline silicon or exotic thin films of rare elements like cadmium and tellurium. A new study finds that unconventional solar cell materials, such as iron pyrite -- fool's gold -- may be a better deal if photovoltaics are expected to meet energy demands of the future. These materials are more abundant and cheaper to extract, which can offset their somewhat lower efficiency.

Scientists have shown that carrier multiplication -- when a photon creates multiple electrons -- is a real phenomenon in tiny semiconductor crystals and not a false observation born of extraneous effects that mimic carrier multiplication. The research shows the possibility of solar cells that create more than one unit of energy per photon.

Japanese researchers have developed a new process to capture light energy -- they "plug" a molecular "wire" directly into a biological photosynthetic system to efficiently conduct the free electrons to a gold electrode.