Solar cells are not easy to build, but a new technology from Notre Dame could, someday, change that. It involves a nanoparticle paste made from t-butanol, water, cadmium sulfide and titanium dioxide. Here, you watch the process of constructing a solar cell this way and see why it could be easier and cheaper than current options. The downside: These solar cells won’t be coming to a neighborhood near you anytime soon. They’re in the early stages of research and are still only 1% efficient at converting solar energy to electricity. (Standard solar cells tend to be closer to 25% efficient.)