For years physicists have sought a revolutionary approach to solar energy. Instead of working on ordinary solar cells, which require many photons to produce a single electron, they have focused on quantum dots, which need only one photon to produce multiple electrons. This process, called multiple exciton generation (MEG), has so far worked only in toxic materials like lead. Now Arthur Nozik at the National Renewable Energy Laboratory has proved that MEG works in silicon, the material that constitutes most solar cells. The next step: Prove that MEG can be scaled out of the lab to become commercially viable.