Thanks to Arizona State University researchers, solar cells are becoming more and more efficient. Improving solar cell efficiency brings down the cost of solar electricity, which allows this source of renewable energy to become a viable option for more people. Recently, Senior Sustainability Scientist Zachary Holman and Assistant Research Professor Zhengshan “Jason” Yu in ASU’s Ira A. Fulton Schools of Engineering broke their own world-record efficiency percentage by creating a tandem solar cell stacked with perovskite and silicon that is 25.4 percent efficient. This was accomplished in conjunction with researchers at the University of Nebraska–Lincoln. The team estimates they’ll be nearing 30 percent tandem efficiency within two years. Silicon solar cells make up 95 percent of the solar panels made today. The perovskite/silicon tandem has the potential to transform mainstream silicon technology and support the U.S. Department of Energy’s SunShot Initiative to cut the cost of solar-generated electricity by half between 2020 and 2030. At the cost target of $0.03 per kilowatt hour, solar electricity would be among the least expensive options for new power generation.