Density Functional Theory Investigation of Fulvene-Derivatized Fullerenes as Candidates for Organic Solar Cells.

Interest within the scientific community in organic solar cells has been on the rise over the last two decades as researchers respond to increasing demands for alternative renewable energy sources. Fulvene, fullerene, and endohedral metallofullerene derivatives have individually shown great promise as efficient charge transfer agents. Despite the heavy demand for research in this area, there have been no studies reported to date that explore the electronic behavior of molecules containing both fullerene and fulvene groups. The lack of interest may be attributed to inherent limitations and inaccuracy in most density functional theory (DFT) band gap calculations for large molecules. Herein we present a systematic computational investigation of the band gaps and dipole moments of several test fullerene-fulvene molecules using a novel DFT method that has been modified to allow accurate computation of the band gaps of this class of molecules. Calculated results showed promising low band gap energies and attractive conductive properties for all fullerene-fulvene derivatives. This new DFT method can conceivably be an invaluable tool that can provide predictive insight into the suitability of similar high molecular weight materials for application in organic solar cell devices.