A team at Michigan State University has developed an untinted solar window that absorbs and generates electricity from the near-infrared wavelengths of sunlight. Previous transparent luminescent solar concentrators have demonstrated better efficiency, but at the cost of being highly colored. The new device incorporates colorless, NIR-absorbing organic salts and diverts the invisible light photovoltaic cells at its edges. A transparent luminescent solar concentrator module. Courtesy of Yimu Zhao/University of Michigan. “Because the materials do not absorb or emit light in the visible spectrum, they look exceptionally transparent to the human eye,” said MSU professor Dr. Richard Lunt. The device has a solar conversion efficiency close to 1 percent; the team’s goal is to reach efficiencies beyond 5 percent. The best colored luminescent solar concentrator has an efficiency of around 7 percent. The technology could be used in buildings, cell phones and other devices with flat, clear surfaces, the researchers said. The research was published in Advanced Optical Materials (doi: 10.1002/adom.201400103). For more information, visit www.msu.edu.