The National Institute of Standards and Technology (NIST) recently reported that polymer solar cells, which can effectively be printed onto sheets akin to printing a newspaper from a long spool of paper, are coming closer to practicality. Such solar cells are much cheaper to produce can be placed on a variety of substrates and use less materials.
The research, published in Energy & Environmental Science, was led by NIST and included an international team of researchers. They found that the ‘sweet spot’ for mass-producing polymer solar cells will come when polymer solar cells reach 10 percent efficiency and they were able to produce polymer solar cells that were more than 9.5 percent efficient using a mock-up high-volume, roll-to-roll processing method. They said it was almost as good as “small-batch devices made with spin-coating, a method that produces high-quality films in the laboratory but is commercially impractical since it wastes up to 90 percent of the initial ink.”
“Efficient roll-to-roll fabrication is key to achieving the low-cost, high-volume production that would enable photovoltaics to scale to a significant fraction of global energy production,” explained He Yan, a collaborator from Hong Kong University of Science and Technology.
The researchers also found that mass produced solar cells, which they expected to have similar texture and molecular density, aren’t the same. But the lab-made varieties are only slightly more efficient at 11 percent efficiency. In such manufacturing the polymers are deposited on a substrate like an ink.
“The ‘rule of thumb’ has been that high-volume polymer solar cells should look just like those made in the lab in terms of structure, organization and shape at the nanometer scale,” said Lee Richter, a NIST physicist who works on functional polymers. “Our experiments indicate that the requirements are much more flexible than assumed, allowing for greater structural variability without significantly sacrificing conversion efficiency.”Tweet