Stanford University engineers have developed the first solar cell made entirely of carbon – a promising alternative to the expensive materials used in photovoltaic devices today. The thin-film prototype is made of carbon materials that can be coated from solution – a technique that has the potential to reduce manufacturing costs.
“Every component in our solar cell, from top to bottom, is made of carbon materials,” says Stanford graduate student Michael Vosgueritchian. “Other groups have reported making all-carbon solar cells, but they were referring to just the active layer in the middle, not the electrodes.”
The experimental solar cell consists of a photoactive layer, which absorbs sunlight, sandwiched between two electrodes. In a typical thin film solar cell, the electrodes are made of conductive metals and indium tin oxide. One drawback of the all-carbon prototype is that it primarily absorbs near-infrared wavelengths of light, contributing to a laboratory efficiency of less than 1 percent – much lower than commercially available solar cells.