Excimer Formation Dynamics of Intramolecular π-Stacked Perylenediimides Probed by Single-Molecule Fluorescence Spectroscopy

摘要

Abstract: π-Stacked perylenediimides (PDIs) have strong electronic communication between the individualnmolecules and show great promise as organic electronic materials for applications in field effect transistors,nphotovoltaics, and liquid crystal displays. To gain further insight into the relationship between conformationalnbehaviors and electronic structures of π-stacked PDIs, we have investigated changes in the excimer-likenstate of cofacial PDI oligomers that result from π-stacking in real time by monitoring the single-moleculenfluorescence intensity and lifetime trajectories in a PMMA polymer matrix. The fluorescence intensity andnlifetime of π-stacked perylenediimides are sensitive to the degree of π-orbital interactions among PDI units,nwhich is strongly associated with molecular conformations in the polymer matrix. Furthermore, our resultsncan be applied to probe the conformational motions of biomolecules such as proteins.