Special deal on photon-to-electron conversion: Two for one!
Throughout decades of research on solar cells, one formula has been considered an absolute limit to the efficiency of such devices in converting sunlight into electricity: Called the Shockley-Queisser efficiency limit, it posits that the ultimate conversion efficiency can never exceed 34 percent for a single optimized semiconductor junction. Now, researchers at MIT have shown that there is a way to blow past that limit as easily as today’s jet fighters zoom through the sound barrier — which was also once seen as an ultimate limit. Their work appears this week in a report in the journal Science, co-authored by graduate students including Daniel Congreve, Nicholas Thompson, Eric Hontz and Shane Yost, alumna Jiye Lee ’12, and professors Marc Baldo and Troy Van Voorhis.The principle behind the barrier-busting technique has been known theoretically since the 1960s, says Baldo, a professor of electrical engineering at MIT. But it was a somewhat...