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Light management in flexible thin-film solar cells - the role of nanoimprinted textures and tilted surfaces

: Wilken, Karen; Paetzold, Ulrich W.; Meier, Matthias; Smeets, Michael; Prager, Nicole; Fahland, Matthias; Finger, Friedhelm; Smirnov, Vladimir


IEEE Journal of Photovoltaics 5 (2015), No.6, pp.1646-1653
ISSN: 2156-3381
Journal Article
Fraunhofer FEP ()
flexible substrates; solar cells; Texturing; light trapping; thin films

We present the application of ultraviolet (UV) nanoimprint lithography for the replication of advanced light management schemes in flexible thin-film solar cells. The approach is maintained entirely at low temperatures, which are required for the development of flexible solar cells on low-cost transparent polymer films. Light-scattering properties are significantly improved by this technique, and thin-film silicon solar cells prepared on these substrates show a substantial improvement in performance due to the nanoimprinted texture. We further investigate the effect of various incident angles of the light on the short-circuit current density (Jsc) of the solar cell and evaluate the corresponding performance of a flexible solar cell in a bent state. Our results show that in the case of imprinted texture, the Jsc and efficiency is reduced within 5% in a bent case of a semicircle when a reduction of the effective illumination area with angle is not taken into account. Overall, the solar cell on imprint-textured polyethylene terephthalate (PET) film shows an increased Jsc for the entire range of incident angles and bent states compared with the nonimprinted PET substrate.