Black silicon surfaces on solar cells can elevate their efficiency to new levels, research out of Finland reports. Black silicon, with a surface reflectance of below 1 percent, has long been an attractive material for use in photovoltaic and other photonic applications. However, black silicon (b-Si) has poor charge carrier transport properties and increased surface recombination, resulting in poor spectral response, most notably at short wavelengths. Black silicon surfaces on solar cells can elevate the efficiency to new levels, research at Aalto University has found. Courtesy of Päivikki Repo. Now, with more effective surface passivation methods available, b-Si has become a viable material for solar cells and other technologies, said Päivikki Repo, a researcher at Aalto University. Together with scientists at Fraunhofer Institute for Solar Energy Systems ISE, Repo and colleagues developed black-silicon-based high-efficiency solar cells with high-sensitivity light response by applying atomic layer coating to the cell. This yielded extremely good surface passivation of the silicon nanostructures while simultaneously reducing the reflectance at all wavelengths. The research appeared in the Journal of Photovoltaics (doi: 10.1109/JPHOTOV.2012.2210031). For more information, visit: www.aalto.fi/en