Light Management in Thin Film Solar Cells

32nd European Photovoltaic Solar Energy Conference and Exhibition; 1216-1218
Application of structured back reflectors, made by Nano-Imprint Lithography is shown to result in excellent light trapping in a-Si and nc-Si cells on steel foil. Applying these concepts we managed to achieve back reflectors with a Haze factor of more than 95% for the entire visible wavelength regime. On these back reflectors, nc- Si and a-Si cells were fabricated and Jscs of more than 24 mA/cm2 for nc-Si cells with an absorber layer thickness of 1000 nm were obtained. We applied the anti-reflection texture on the front glass of a hybrid tandem (in which a c-Si bottom cell was combined with a semi-transparent a-Si top cell) and reached an improvement of the Jsc of the bottom cell of 1.7 mA/cm2. The lacquer that has been developed for textured back reflectors in CIGS solar cells has been applied to make periodic and random textures. First experiments to implement these back reflectors in thin CIGS solar cells were carried out indicating that the growth of CIGS on textured substrates is non-conformal on textures with high aspect ratios. Further modeling, in which this non-conformity is taken into account, is required to determine the optimum textures for CIGS