| Abstract
| - Single-molecule fluorescence spectroscopy was performed on a number of multi-peryleneimide substitutedpolyphenylene dendrimers for the purpose of investigating the parameters which influence the efficiency ofthe dendrimers as single-photon sources at room temperature. Analysis of fluorescence intensity, lifetime,and interphoton arrival time distribution revealed that all measured first-generation dendrimers behave assingle-photon emitters when more than one chromophore is excited by a single excitation pulse regardless ofthe number of constituent chromophores. This is a result of efficient singlet−singlet annihilation, which becomesless efficient in higher-generation dendrimers when the interchromophoric distance increases. The efficiencyof the investigated dendrimers as single-photon sources depends on several other parameters, such as thenature of the surrounding polymer matrix, the number of chromophores, and the extent of interchromophoricinteractions. These parameters mainly affect the frequency of singlet−triplet annihilation, which in turndominates the quality of these multichromophoric dendrimers as single-photon sources. The results reportedhere are important not only for the design of single-photon sources based on single organic molecules butalso for a fundamental understanding of natural and artificial multichromophoric systems.
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