Resonance-shifting to circumvent reabsorption loss in luminescent solar concentrators

• Published in: Nature photonics Vol. 5; no. 11; pp. 694 - 701
• Main Authors: Giebink, Noel C., Wiederrecht, Gary P., Wasielewski, Michael R.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2011; Nature Publishing Group
• Subjects: 639/624/1075/524; Applied and Technical Physics; Concentrators; Devices; Equivalence; Holes; Photovoltaics; Physics; Physics and Astronomy; Quantum Physics; Resonance; Slabs; Strategy; Sun; Tracking
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/nphoton.2011.236

Luminescent solar concentrators (LSCs) provide a simple means to concentrate sunlight without tracking the Sun. These devices absorb and then re-emit light at a lower frequency into the confined modes of a transparent slab, where it is guided towards photovoltaic cells attached to the slab edges. In the thermodynamic limit, a concentration ratio exceeding the equivalent of 100 suns is possible, but, in actual LSCs, optical propagation loss (due mostly to reabsorption) limits the concentration ratio to ∼10. Here, we introduce a general, all-optical means to overcome this problem by ‘resonance-shifting’, in which sharply directed emission from a bilayer 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. Using this strategy, we demonstrate near-lossless propagation for several different chromophores, which ultimately enables a more than twofold increase in concentration ratio over that of the corresponding conventional LSC. Re-absorption losses in luminescent solar concentrators cause concentration performances to be around ten times less than the ideal value. Researchers have now reduced re-absorption by forcing the emission in one region to be off-resonant with the other regions, achieving a two-fold enhancement in concentration performance over conventional devices.