Recently, interest has been growing in using both dielectric and metallic nanostructures for light trapping in photovoltaics and liquid-junction solar cells. Dielectric photonic crystals  have been used to extend the action spectrum of dye-sensitized solar cells, and plasmonic metal nanostructures have been used to enhance light absorption in photovoltaics.  So far few studies have considered the combination of these structures for light trapping.Sub-wavelength periodic texturing of the backing metallic layer of a thin-film solar cell can be used to launch surface plasmon-polariton (SPP) waves, to create a high electric field in the region of the semiconductor close to the metal. This effect however leads to modest gains in light harvesting because gratings interfaced to uniform dielectrics couple only one linear polarization of incident light, and because the enhanced electric field extends only a short distance into the semiconductor. We have recently proposed from modeling studies that a grating interfaced to a dielectric with a periodically varying refractive index (i.e., a photonic crystal) should support multiple SPP modes, which should be excited by incident light of both s- and p-polarization states. This finding has now been verified experimentally by measuring the reflectivity of such structures. With appropriate grating design we observe surprisingly strong coupling of s- as well as p-polarized incident light over a wide range of angles and free space wavelengths. This talk will discuss strategies for incorporating these new metallodielectric nanostructures into thin film solar cells.

Nanostructures for improving the spectral response of photovoltaic cells

246th National Meeting (2013)

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