Analysis of short circuit current gains by an anti-reflective textured cover on silicon thin film solar cells

ABSTRACT The influence of a retro‐reflective texture cover on light in‐coupling and light‐trapping in thin film silicon solar cells is investigated. The texture cover is applied to the front glass of the cell and leads to a reflectance as low as r ≈ 3% by reducing the reflection at the air/glass interface and indirectly also reducing the reflections from the internal interfaces. For weakly absorbed light in the long wavelength range, the texture also enhances the light‐trapping in the solar cell. We demonstrate an increase of the short circuit current density of exemplary investigated thin film silicon tandem solar cells by up to 0.95 mA cm−2 and of the conversion efficiency by up to 0.74% (absolute). For a planar microcrystalline solar cell, the enhancement of light‐trapping was determined from the reduced reflection in the long wavelength range to be up to 17%, leading to an increase of the external quantum efficiency of up to 12%. Copyright © 2012 John Wiley & Sons, Ltd. A texture foil attached to the substrate glass of solar cells surpasses the maximum efficiency gains achievable by anti‐reflective coatings. The photograph shows the substructure of the scattering foil on top of a reflecting silicon wafer. Besides the anti‐reflex effect, the texture enhances the internal light‐trapping.