title: Photophysics of delocalized excitons in carbazole dendrimers.
abstract: The photophysical properties in solution of three generations of carbazole-based dendrons and dendrimers with fluorenyl surface groups were studied using steady-state, time-resolved femtosecond transient absorption and anisotropy, and coherent two-dimensional ultraviolet spectroscopy. It was found that increasing the generation caused a switch in the nature of the emissive state between the first-generation compounds and the second- and third-generation dendrimers. Time-resolved anisotropy measurements revealed low initial anisotropies that decreased with increasing dendrimer generation consistent with increasing intradendrimer interchromophore coupling. Two-dimensional UV spectroscopy showed that the signal from the second- and third-generation dendrimers is the product of multiple chromophores interacting. The maximum number of interacting chromophores is reached by the second generation.
authors.affiliation: Department of Chemistry, 80 St. George Street, University of Toronto, Toronto, Ontario M5S 3H6, Canada.
authors.forename: Inchan
authors.initials: I
authors.lastname: Hwang
authors.forename: Ulrike
authors.initials: U
authors.lastname: Selig
authors.forename: Simon S Y
authors.initials: SS
authors.lastname: Chen
authors.forename: Paul E
authors.initials: PE
authors.lastname: Shaw
authors.forename: Tobias
authors.initials: T
authors.lastname: Brixner
authors.forename: Paul L
authors.initials: PL
authors.lastname: Burn
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Scholes