title: Energy transfer in molecular layer-by-layer films of water-soluble perylene diimides.
abstract: Multilayer films of water-soluble anionic and cationic perylene diimide (PDI) moieties have been prepared using the molecular layer-by-layer method described in an earlier publication (Tang, T. J.; Qu, J. Q.; Müllen, K.; Webber, S. E. Langmuir 2006, 22, 26-28) and the fluorescence intensity compared with and without a base layer prepared using an anionic terrylene diimide dye (n-TDI), which serves as an energy-trapping layer for the PDI exciton. The fluorescence quenching data could be fit equally well to a modification of a model used by Kuhn to describe energy transfer from a J aggregate or a model developed by Kenkre and Wong to describe excitonic transfer. For both models, we obtain a characteristic energy-transfer distance on the order of 5.4 nm. Fluorescence quenching of the PDI via a single Förster energy-transfer step to the n-TDI layer is ruled out on the basis of the observed power-law dependence. We also consider a model in which the excitation is trapped at the outermost surface. This model provides a reasonable fit to the data only if the Kuhn relationship is used.
authors.affiliation: Department of Chemistry and Biochemistry and Center for Nano and Molecular Science, The University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Tingji
authors.initials: T
authors.lastname: Tang
authors.forename: Andreas
authors.initials: A
authors.lastname: Herrmann
authors.forename: Kalina
authors.initials: K
authors.lastname: Peneva
authors.forename: Klaus
authors.initials: K
authors.lastname: Müllen
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Webber