50% Efficient Solar Cells

revscat writes: "MIT's Technology review is reporting that a new material has been developed that could allow for much more efficient solar cells: "Researchers at Lawrence Berkeley National Laboratory (LBNL) have created a new type of semiconductor material designed to improve the efficiency of solar cells by capturing low-energy photons. Traditional solar cells respond only to a narrow spectrum of sunlight, making them highly inefficient. In the language of physicists, solar cells convert light with wavelengths corresponding to the energy it takes for electrons to jump from the valence band to the conduction band. Photons with lower energy pass right through the material. The new semiconductor material can capture these low-energy photons for electricity, which could make solar cells with efficiencies of around 45 percent, compared with 25 percent for conventional cells that use a single semiconductor and 39 percent for cells with layers of mixed semiconductors.""