Hybrid systems consisting of core/shell semiconductor quantum dots (QDs) and organic rylene dyes have been prepared and characterized. Complex formation is mediated by bidentate carboxylate moieties covalently linked to the dye molecules. The complexes were very stable with respect to time (at least months), dilution (sub nM), and precipitation. After preparation in organic solvent, complexes could be easily transferred into water. The strong quenching of QD emission by the dye molecules (transfer efficiencies up to 95%) was satisfactorily modeled by an FRET process. Single complexes immobilized in thin polymer films were imaged by confocal fluorescence microscopy.

Perylenediimide (PDI) dyes have attracted a great deal of attention as they possess excellent photochemical stability, high extinction coefficients, and fluorescence quantum yields. The use of multiple PDI chromophores in one synthetic architecture increases their versatile use and functionality even more. However, bringing multiple chromophores in close proximity also leads to interactions among the chromophores and opens up new photophysical pathways. Here, the synthesis and photophysical characterization, both at the ensemble and single molecule level, of a diphenyl-acetylene linked perylenediimide trimer (3PDIAc) is presented. Förster type energy transfer processes like energy hopping and singlet-singlet annihilation among the chromophores are investigated. Despite the lower singlet-singlet annihilation rate of the phenoxy substituted perylenediimide chromophores (356 ps) versus for example perylenemonoimide (10 ps), the system still behaves as a single photon emitter. Sequential fitting of the dipole emission pattern recorded with defocused wide field imaging of single 3PDIAc, immobilized in a PMMA polymer film, demonstrated that emission can switch between sequential emission of all of the chromophores or emission from one chromophore that likely is the lowest in energy.