Fullerene-based processable polymers as plausible acceptors in photovoltaic applications

To develop n-type processable polymeric materials for photovoltaic applications, a series of polymers was synthesized by grafting fullerene C₆₀ onto polystyrene (PS). Grafted polymers were studied and compared with PS:fullerene blends. Electronical and electrical properties were first measured to define the minimal amount of C₆₀ required for solar cells application. Then, thermal properties and rheological behavior of grafted polymers were analyzed to determine whether they could be processed from the melt. A throughout experimental study revealed that C₆₀-grafted polymers exhibit two thresholds. The first threshold at 3–4 vol % (detected by electrical conductivity, electron mobility, and melt viscosity measurements) is associated to the percolation of C₆₀ molecules. The second threshold (evidenced by glass transition and melt viscosity measurements and confirmed by optical and atomic force micrograph observations) at about 12–13 vol % is assumed to be related to the formation of C₆₀ aggregates. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013