Theoretical Study of Bis-Porphyrin-Fullerene Supramolecular Complex Designed for Photovoltaic Devices

A computational study of a bis-porphyrin-fullerene supramolecular complex designed for photovoltaic devices using semiempirical AM1 method is presented. The study of the frontier molecular orbitals in the ground state has revealed that porphyrin part is an electron donor moiety, while fullerene guest is an electron acceptor. The electronic properties of the excited singlet states of 1@C60add complex indicate electron transfer from porphyrin to fullerene moiety. Introduction. Porphyrin-fullerene supramolecular systems and dyads have been extensively studied in order to examine donor-acceptor interactions. These systems are highly interesting in view of the possible supramolecular modulation of electronic properties of fullerenes.[1] Donor-acceptor interactions within fullerene-porphyrin architectures are important for multi-component model systems designed for transmission and process of solar energy. [2] Various fullerene-porphyrin donor-acceptor dyads were reported [3],[4],[5] and photovoltaic cells based on a fullerene-porphyrin dyads exhibited good quantum efficiency.[6] ,[7] Most of these supramolecular photocurrentgenerating devices are based on covalently linked components using fullerenes and porphyrins. There are also literature examples of self-assembled supramolecular donor-acceptor (D-A) model systems employing metal complexation, such as zinc-porphyrin (ZnP), ZnP-C60 systems and DABCO[8],[9] and bisZnP (D)-pyridine (A) systems.[10],[11] It was found that dipyridine-linked acceptors can be assembled with two coordination bonds to bisZnP donors.[12] Time-resolved fluorescence studies showed that the coordination bonds between the donor and acceptor do not make significant influence on the electron transfer (ET). [4] Therefore, supramolecular ET systems Zagreb, Croatia University of