Atomic force microscope images the reveal the surface morphology of the active layers without Al contacts. The leftmost frame shows a PCBM:P3HT sample without dye. The two columns show the effects of green dye (1, top row) and red dye (DR1, bottom row) at 5% and 10% weight concentrations with respect to the PCBM content. The addition of both dyes clearly enhances aggregation in the samples.