Broadband optical absorption enhancement through coherent light trapping in thin-film photovoltaic cells.

Electrical Engineering, Stanford University, Stanford, CA 94305, USA.
Optics Express (Impact Factor: 3.55). 05/2008; 16(8):5385-96. DOI: 10.1364/OE.16.005385
Source: PubMed

ABSTRACT We show that optical absorption in thin-film photovoltaic cells can be enhanced by inserting a tuned two-component aperiodic dielectric stack into the device structure. These coatings are a generalization and unification of the concepts of an anti-reflection coating used in solar cells and high-reflectivity distributed Bragg mirror used in resonant cavity-enhanced narrowband photodetectors. Optimized two-component coatings approach the physically realizable limit and optimally redistribute the spectral photon density-of-states to enhance the absorption of the active layer across its absorption spectrum. Specific designs for thin-film organic solar cells increase the photocurrent under AM1.5 illumination, averaged over all incident angles and polarizations, by up to 40%.

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