Intramolecular and intermolecular resonant energy transfer of a free-base tetraphenylporphyrin–fullerene dyad: A DFT and TDDFT study

Intramolecular and intermolecular resonant energy transfer (RET) of a free-base tetraphenylporphyrin–N-methyl-pyrrolidinofullerene (TPP–MPC60) molecular dyad are studied by using the density functional theory (DFT) and the time-dependent DFT. The Fermi golden rule is used along with the extended dipole model to describe the electronic coupling in calculating the energy transfer rates. Among the PBE, PBE0, and B3LYP functionals the PBE is observed to predict the experimentally observed intramolecular RET rate the best, as well as the spectroscopic properties of TPP. The PBE calculated intramolecular RET rate is of the same order of magnitude as the experimentally observed rate and is observed to be also almost the same as the intermolecular energy transfer between two adjacent molecules.