Förster-induced energy transfer in functionalized graphene

Journal Of Physical Chemistry C 118, 9283 - 9289 (2014)

Förster-induced energy transfer in functionalized graphene

E. Malic, H. Appel, O. T. Hofmann, A. Rubio

Carbon nanostructures are ideal substrates for functionalization with molecules, since they consist of a single atomic layer giving rise to an extraordinary sensitivity to changes in their surrounding. The functionalization opens a new research field of hybrid nanostructures with tailored properties. Here, we present a microscopic view on the substrate-molecule interac- tion in the exemplary hybrid material consisting of graphene functionalized with perylene molecules. First experiments on similar systems have been recently realized illustrating an extremely efficient transfer of excitation energy from adsorbed molecules to the carbon sub- strate1–3 - a process with a large application potential for high-efficiency photovoltaic devices (light harvesting) and biomedical imaging and sensing (photo-detection). So far, there has been no microscopically founded explanation for the observed energy transfer. Based on extensive first-principle calculations, we have explicitly investigated the different transfer mechanisms revealing the crucial importance of Förster coupling. Due to the efficient Coulomb interaction in graphene, we obtain strong Förster rates in the range of fs−1. We investigate its dependence on the substrate-molecule distance R and describe the impact of the momentum transfer q for an efficient energy transfer. Furthermore, we find that the Dexter transfer mechanism is negligibly small due to the vanishing overlap between the involved strongly localized orbital functions. The gained insights are applicable to a variety of carbon-based hybrid nanostructures

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