Electronic deactivation and energy transfer in doped oligophenylenevinylene nanoparticles

Suspensions of oligopllenylenevinylene (nPV) nanoparticles with n = 2 vinyl ene units are doped with nPVs of longer chainlengths, n = 3-5. Absorption a nd fluorescence spectroscopy and steady slate and time-resolved fluorescenc e anisotropy measurements are used to determine the photophysical propertie s of the suspensions. Undoped nanoparticles form highly oriented H-aggregat es with low fluorescence quantum yields (Phi(F) approximate to 0.1). Introd uction of bulky substituents into the particle constituting molecules pertu rbs thr intermolecular orientation. Upon doping, efficient energy transfer to the dopants is found, changing the color and leading to enhancement of t he fluorescence quantum yields up to Phi(F) = 0.6. The intermolecular orien tation is not changed upon doping.