Electronic Energy Transfer in Multichromophoric Arrays. The Effects of Disorder on Superexchange Coupling and Energy Transfer Rate

Abstract

The effects of diagonal (site energy) and off-diagonal (intermolecular interaction) disorder arising from the distribution of ionization energies on superexchange coupling and the corresponding electronic energy transfer (EET) rate are considered. The effective donor−acceptor coupling is obtained using the Dyson's equations-based solution of the Green's function for both the orthogonal and nonorthogonal basis sets. In a disordered multichromophoric array, the effective superexchange coupling is shown to be enhanced. Furthermore, the competing roles of the multiple pathways when next-to-nearest-neighbor interactions exist behave differently depending on the type and extent of disorder. It is demonstrated that the exponential falloff of the energy transfer rate with increasing donor−acceptor distance weakens when disorder is present. Moreover, this exponential decay is more apparent when the donor−bridge energy gap is reduced. A method to treat EET at the molecular orbital level using Dyson's equations is a...