Argonne National Laboratory Solar Energy Systems U.S. Department of Energy

Research: Concentrating Sunlight

Resonance-shifting to circumvent reabsorption loss in luminescent solar concentrators

solar concentrator
A specialized piece of glass called a luminescent solar concentrator can intensify incoming light. The green and orange rings are produced by its fluorescence.

The Center for Nanoscale Materials Nanophotonics Group, collaborating with researchers at Northwestern University, have designed and tested a new form of luminescent solar concentrator (LSC) that enables a more than two-fold increase in concentration ratio over that of conventional LSCs. LSCs have traditionally been studied as a means to concentrate sunlight without tracking the Sun.  These devices operate by absorbing light and then re-emitting it at lower frequency, typically into the confined modes of a transparent slab, where it is transported toward photovoltaic cells attached to the edges.  In principle, concentration ratio exceeding the equivalent of 100 suns is possible, however, in actual LSCs, optical propagation loss due mostly to reabsorption limits the concentration ratio to ~10.  In this work, a general, all-optical means to overcome this problem by ‘resonance-shifting’ is introduced, in which sharply directed emission from a bi-layer cavity into the glass substrate returns to interact with the cavity off-resonance at each subsequent bounce, significantly reducing reabsorption loss en route to the edges.  The ‘resonance-shifting’ is achieved by patterning nanoscale thickness changes onto the bi-layer cavity, thereby altering the cavity resonance condition as a function thickness. Using this strategy, near-lossless emission propagation for several different chromophores has been demonstrated.

N.C. Giebink, G.P. Wiederrecht, and M.R. Wasielewski, “Resonance-shifting to circumvent reabsorption loss in luminescent solar concentrators,” Nat. Photon. 5, 694-701 (2011)


March 2013


Gary Wiederrecht


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