Perovskite

Guest: Michael Graetzel, Director of the Laboratory of Photonics and Interfaces at the Ecole Polytechnique Federal de Lausanne  The cost of solar energy has been dropping rapidly in recent years, as scientists find better, cheaper ways to build panels that can convert sunlight to electricity.  Traditionally, those panels have been coated in silicon, but there’s increasing excitement over a mineral found in the Earth’s mantle called “perovskite” which seems to be much better at absorbing sunlight. These minerals have been known about for a hundred years, but their photovoltaic properties were fairly recently discovered by accident when a team at the Laboratory of Photonics and Interfaces at the Ecole Polytechnique Federal de Lausanne used colorful perovskite crystals as a molecular dye on solar cell.  Graetzel says that perovskite “comes as a gift from God. The crystals that are formed are unusually pure. Silicon purification are very costly. Perovskite comes out very pure.—very few materials have that property.”