Intramolecular charge transfer in the porphyrin-oligothiophene-fullerene triad

Intramolecular charge transfer (ICT) in porphyrin-oligothiophene-fullerene triad was reported experimentally [J. Ikemoto, K. Takimiya, Y. Aso. T. Otsubo, M. Fujitsuka, O. Ito, Org. Lett. 4 (2002) 309], and the weak distance dependence of the oligothiophene spacer was found. In this Letter, ICT in this triad is theoretically investigated with quantum chemistry method as well as the 2D and 3D real space analysis methods. The calculated transition energies and oscillator strengths are consistent with the experimental data. The theoretical analysis with 2D and 3D real space analysis reveal that there are two ICT mechanisms. The experimental weak distance dependence of the oligothiophene spacer is benefitted from the superexchange mechanism.