Organic solar cells that can be painted or printed on surfaces are increasingly efficient, and now show promise for incorporation into applications like clothing that also require them to be flexible. National Science Foundation-funded engineers have developed flexible organic photovoltaics that could be useful where constant, low-power generation is sufficient. Organic solar cells rely on carbon-based materials including polymers, as opposed to hard, inorganic materials like silicon, to capture sunlight and translate it into current. Organics are also thin, lightweight, semitransparent and inexpensive. While middle-of-the-road, commercial, silicon-based solar cells perform at about 22 percent efficiency -- the amount of sunlight converted into electricity -- organics top out at around 15 percent. One approach to fixing the brittle problem would be to find polymers or other organic semiconductors that are flexible by nature, but the researchers took another tack. Rather than make a mesh and pour in the semiconducting polymers, the researchers mixed in sulfur-based thiol-ene reagents. The molecules blend with the polymers and then crosslink with each other to provide flexibility.
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