Funneling the sun’s energy
The quest to harness a broader spectrum of sunlight’s energy to produce electricity has taken a radically new turn, with the proposal of a “solar energy funnel” that takes advantage of materials under elastic strain.“We’re trying to use elastic strains to produce unprecedented properties,” says Ju Li, an MIT professor and corresponding author of a paper describing the new solar-funnel concept that was published this week in the journal Nature Photonics.In this case, the “funnel” is a metaphor: Electrons and their counterparts, holes — which are split off from atoms by the energy of photons — are driven to the center of the structure by electronic forces, not by gravity as in a household funnel. And yet, as it happens, the material actually does assume the shape of a funnel: It is a stretched sheet of vanishingly thin material, poked down at its center by a microscopic needle that indents...