Michael Gratzel. Portrait of the German photochemist Michael Gratzel (born 1944) at the award ceremony for the 2010 Millennium Technology Prize. Gratzel is a professor at the Ecole Polytechnique Federale de Lausanne, Switzerland, where he directs the Laboratory of Photonics and Interfaces. He pioneered research on energy and electron transfer reactions in mesoscopic-materials and their optoelectronic applications, and the use of nanomaterials in lithium ion batteries. He was awarded the 20120 Millennium Technology Prize for his inventing a new type of solar cell based on dye-sensitised mesoscopic oxide particles. Photographed in Helsinki, Finland, on 9th June 2010.