 92% of all of the solar cells that are being manufactured now are made of crystalline silicon. Perovskites are exciting compared to conventional semiconductors used in solar cells. Perovskite refers to a certain crystal structure. Some of the great advantages of perovskites are that they are a thin film technology and can be easily printed on plastic substrates, very flexible lightweight substrates. We report the discovery of a new perovskite semiconductor with a small band gap. We were able to use it along with another perovskite that has a high band gap to make a tandem solar cell. One of these solar cells absorbs high energy photons so that's blue and green light. It uses this to generate a high voltage and then the second solar cell which has a much smaller band gap absorbs lower energy light such as the red and the infrared. When you stack these together you sum up their voltages and you can reach a higher performance than you ever can for a single solar cell so we can have that combination of low cost and highest possible performance. I'm very optimistic that we will have panels with efficiencies above 25%. We already have 20% when these materials are optimized. We're going to be able to get a world record efficiency of 30% in three to five years.