Influence of the spatial photocarrier generation profile on the performance of organic solar cells

We investigate the impact of the interplay of charge carrier drift and diffusion on the fill factor of organic solar cells. Thin film interferences lead to strong gradients in the photocarrier generation profile. By means of numerical simulations, we show that the shape of the absorption profile is crucial for the efficiency of organic solar cells. High absorption in the peripheral areas of the active layer advantages an unfavorable diffusion current which leads to a reduction of the fill factor. Our work suggests design rules for the optical optimization of organic solar cells.