| Abstract
| - The electronic parameters of fullerenes are essential for their potentials used as active layers in organic solar cells. Two isomeric forms of the C60 ([5,6] fulleroid and [6,6] methanofullerene), named [60] PCBM (phenyl-C61-butyric acid methyl ester) clusters, were calculated using the B3LYP method with the 6-31G(d) basis set. It has been found that the contraction of C6−6 double bonds is favorable for addition. The first adiabatic electron affinity (AEA) for [60] PCBM is similar to that for C60. The energy gaps between the highest-occupied molecular orbital (HOMO) and the lowest-unoccupied molecular orbital (LUMO) of [60] PCBM have been reduced compared with C60. PCBM derivatives show an increased level of LUMO of fullerenes. From the natural charge populations, it has been found that adding a PCBM unit onto the C60 cages does not change the charge populations remarkably; attaching a PCBM has no effect on the electronic structures of C60. The results of theoretical calculation suppose that PCBM is not involved in the process of photoelectric conversion, but it plays a key role in adjusting the level of HOMO−LUMO for increasing photoelectric conversion efficiencies.
|
