The efficiency of organic bulk heterojunction solar cells depends crucially on charge transport in the composite. The charge carrier mobilities in common polymer:fullerene blends are rather low and depend strongly on the film morphology. Here we show the improvement of performance of canonical polymer:fullerene solar cells by embedding highly dispersed Mo6S9-xIx nanowires within their active layer. Adding 0.5 wt% of nanowires raises both the fill factor and the open-circuit voltage, resulting in 18% higher power conversion efficiency. We attribute this increase to improved charge transport by the embedded nanowire mesh and envisage further improvement by using higher nanowire weight fractions and thinner nanowire bundles. (C) 2014 Elsevier B.V. All rights reserved.