The steady improvement of the efficiency and stability of Organic Photovoltaics (OPV) over the last few years has been driven by the development of new materials with desirable optical and electronic properties. The rules that guide the design of new materials are often based on focused studies of model compounds that allow for a deeper understanding of the underlying photophysics of these complex systems. Here we discuss trifluoromethylfullerenes (TMFs) as model systems for understanding the dynamics of photoinduced charge generation and decay in a prototypical OPV photoactive layer comprising a conjugated polymer and TMFs. We take advantage of the tunability of the properties of TMFs, afforded by controlling the addition pattern on the C<sub>60</sub> cage, to vary their reduction potential, LUMO position on the C<sub>60</sub> cage and the inter-fullerene distance in the polymer-TMF film. We probe charge generation in the polymer-fullerene blend in 100 fs – 500 ns time scales with pump-probe spectroscopy. We show that charge generation depends on the electronic transport properties within the fullerene phase and we determine the properties of the fullerene, at the molecular level, that lead to long lived (&gt;500 ns) photoinduced free carriers in the blend. We discuss these findings with respect to new OPV materials design. Finally, we show that fluorinated fullerenes can be successful not only as model compounds but also as practical alternatives to existing materials in OPV device applications.

Trifluoromethylfullerenes as model compounds for unraveling the photophysics of organic photovoltaics

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.