Discovery: Everybody loves the idea of photovoltaic solar cells: endless clean electricity generated directly from sunlight. The problem lies in the messy reality of making the technology work well. For instance, says Boston College physicist Michael J. Naughton, the cells’ two functions–capturing light and making energy–pull the optimum design for a solar panel in opposite directions. “‘Photo’ wants it thick,” Naughton says, “but ‘voltaic’ wants it thin.” So Naughton and other like-minded scientists are…