Modeling the optical absorption within conjugated polymer/fullerene-based bulk-heterojunction organic solar cells

In this paper, we report our results on the modeling of the optical properties of the bulk-heterojunction “plastic solar cells”, consisting of a solid-state blend of the conjugated polymer poly-[2-(3,7-dimethyloctyloxy)-5-methyloxy]-para-phenylene-vinylene and the fullerene C60 derivative 1-(3-methoxycarbonyl) propyl-1-phenyl [6,6]C61. Upon illuminating these cells with the standard AM 1.5 solar spectrum, the short circuit current can be determined for any given internal quantum efficiency as a function of the active layer thickness. In addition, the depth profiles of photoinduced charge generation rates are calculated. Based on the agreement of this modeling with experimentally determined efficiencies of these solar cells, an internal quantum efficiency of about 80% has been estimated.