Optimization of Microtextured Light-Management Films for Enhanced Light Trapping in Organic Solar Cells Under Perpendicular and Oblique Illumination Conditions

To improve light absorption in organic solar cells, microscale surface-textured light-management (LM) films are applied on top of the front glass substrate. In this study, numerical simulations are employed to determine the optimal texture of the LM films that would result in the highest short-circuit current density of the solar cells in perpendicular, as well as oblique, illumination conditions. Different types of 2-D periodic surface textures are analyzed (pyramidal, parabolic, sinusoidal), and the effects of the period and groove height sizes are investigated. Numerical simulations are based on a model that combines geometric optics and wave optics and, thus, enables simulation of light propagation through the thick microtextured LM film and glass, as well as thin layers of the device, respectively. Results show that parabolic textures are the most advantageous for the solar cells to achieve high performance operating in changing illumination conditions. When properly optimized, they enable over 14% boost of the short-circuit current density in a broad range of illumination incident angles, with the maximum of 22% for perpendicular incidence, with respect to that of the nontextured cell.