Light Management in Flexible Thin-Film Solar Cells—The Role of Nanoimprinted Textures and Tilted Surfaces

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 (J_sc) 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 J_sc 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 J_sc for the entire range of incident angles and bent states compared with the nonimprinted PET substrate.