Leveraging the cost of photovoltaic power through advances in solar concentration
Speaker: Dr. Noel C. Giebink, Argonne National Laboratory
Series: Electrical Engineering Departmental Seminar
Location: Engineering Quadrangle B205
Date/Time: Thursday, March 17, 2011, 4:30 p.m. - 5:30 p.m.
Sunlight is a diffuse energy resource and thus all methods of solar energy capture and conversion have one feature in common – concentration. In this talk, I will focus on some of our recent efforts in luminescent solar concentration, a concept originally introduced three decades ago as a simple route to obtain high concentration for photovoltaic cells without tracking the sun. Luminescent concentrators (LSCs) traditionally consist of a transparent slab embedded with a chromophore that absorbs sunlight and re-emits it back into the slab, where it is trapped by total internal reflection and absorbed by photovoltaic cells attached to the edges. Concentration ratios exceeding 100 are theoretically possible, however, in practice, the overlap between chromophore absorption and emission spectra ultimately leads to unacceptable reabsorption losses that limit the concentration ratio to ~10, and hence the utility of LSCs to date.
Recently, we have developed an all-optical means of overcoming the reabsorption problem by incorporating a simple bilayer cavity on top of a transparent substrate and continuously varying its resonance across the lateral dimensions of the concentrator. In this ‘resonance-shifting’ approach, sharply directed emission from the cavity continuously avoids the narrow reabsorption resonance at each subsequent bounce and hence propagates with low loss to the substrate edges. This strategy is demonstrated for several different organic chromophores with varying degrees of reabsorption overlap, with near-lossless propagation and a significant improvement in concentration ratio demonstrated for each case.
Noel Giebink is currently the George Wells Beadle postdoctoral fellow at Argonne National Laboratory in conjunction with an appointment at Northwestern University through the Argonne-Northwestern Solar Energy Research Center. He received his Ph.D. in electrical engineering from Princeton University and holds undergraduate degrees in both Physics and Engineering Science from Trinity University (TX). His research interests highlight the synthesis of organic and inorganic materials in optoelectronic and plasmonic devices, with a particular emphasis on applications for solar energy conversion and solar fuels generation.