In this work, we seek to improve the long term stability of organic photovoltaic (OPV) active layers under white light illumination in air through the use of perfluoroalkylfullerene acceptors. The rates of irreversible photobleaching of blends of donor polymers and fullerene acceptors were found to correlate well with the electron affinity of the fullerene, provided that the polymer and fullerene were well blended. The degree of blending of both fluorinated and nonfluorinated donor polymers with fullerene acceptors was quantified in terms of domain size using scanning tunneling microscopy imaging. We observed, for example, that C60(CF3)2 had a pronounced affect on stabilizing the donor polymer towards photodegradiation if that donor polymer contained fluorinated benzothiadiazole groups that could help promote miscibility. However, a fullerene containing a perfluorinated aryl group was found more appropriate for stabilizing fluorinated and non-fluorinated donor polymers such as those based on thienopyrrolodione and benzodithiophene (e.g., PBDT-TPD). A summary of design rules for improving photostability of active layer blends using fluorination strategies will be discussed.

Influence of perfluoroalkylated fullerene acceptors on morphology and photodegradation of organic photovoltaic active layers

254th National Meeting (2017)

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