Described herein are photovoltaic devices including self-assembling fullerene derivatives. In one embodiment, a photovoltaic device includes a first electrode layer, a second electrode layer, and an active layer disposed between the first electrode layer and the second electrode layer. The active layer is configured to absorb incident light to produce a first type of charge carrier that is transported to the first electrode layer and a second type of charge carrier that is transported to the second electrode layer. The active layer includes self-assembled molecules of a fullerene derivative to provide a conductive path through at least a portion of the active layer.