Nanoimprint texturing of transparent flexible substrates for improved light management in thin‐film solar cells

We present a nanoimprint based approach to achieve efficient light management for solar cells on low temperature transparent polymer films. These films are particularly low‐priced, though sensitive to temperature, and therefore limiting the range of deposition temperatures of subsequent solar cell layers. By using nanoimprint technology, we successfully replicated optimized light trapping textures of etched high temperature ZnO:Al on a low temperature PET film without deterioration of optical properties of the substrate. The imprint‐textured PET substrates show excellent light scattering properties and lead to significantly improved incoupling and trapping of light in the solar cell, resulting in a current density of 12.9 mA/cm², similar to that on a glass substrate. An overall efficiency of 6.9% was achieved for a flexible thin‐film silicon solar cell on low cost PET substrate. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)