The Thick and Thin of Solar Cells

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Date/Time:Monday, 14 Feb 2011 from 4:10 pm to 5:10 pm
Location:Physics, Room 5
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Eric Schiff (Syracuse University)

Abstract: Like MacDonald's hamburgers, billions of solar modules have been sold. In this talk I will concentrate on the physics of their thinness. "Thin film" solar cells are typically microns thick, and they are usually made from disordered materials: nanocrystalline and amorphous semiconductors, polymers, organics, even mesoporous titania. I will suggest that these typical thicknesses are an upper limit that is consistent with what we know - experimentally - about disorder-induced, Anderson localization near band-edges. While necessitated by disorder, thinness can be advantageous is reducing the cost of a solar cell - as long as the sunlight is collected efficiently. Here too there's an elegant fundamental argument that sets an "ergodic" or classical limit for how effectively solar photons can be trapped in a cell. Many workers are gambling that this limit can be exceeded, perhaps by using surface plasmon excitations at semiconductor-metal interfaces. I'll present an argument that this may be possible, and survey some of the experimental work being done to realize supraclassical light-trapping.

Bio: Eric Schiff received his B.S. from Caltech and his Ph.D. in Physics from Cornell (with Al Sievers). He was a post-doc with Hellmut Fritzsche at the University of Chicago. He has been a Physics Professor at Syracuse University since then, also serving as the Chair of the Physics Department. His research has focused on the optoelectronic properties of unconventional semiconductors such as amorphous silicon and mesoporous titania, as well as on the applications of these materials in solar cells.