Electronic deactivation and energy transfer in doped oligophenylenevinylene nanoparticles

Suspensions of oligopllenylenevinylene (nPV) nanoparticles with n = 2 vinylene units are doped with nPVs of longer chainlengths, n = 3-5. Absorption and fluorescence spectroscopy and steady slate and time-resolved fluorescence anisotropy measurements are used to determine the photophysical properties of the suspensions. Undoped nanoparticles form highly oriented H-aggregates with low fluorescence quantum yields (Phi(F) approximate to 0.1). Introduction of bulky substituents into the particle constituting molecules perturbs thr intermolecular orientation. Upon doping, efficient energy transfer to the dopants is found, changing the color and leading to enhancement of the fluorescence quantum yields up to Phi(F) = 0.6. The intermolecular orientation is not changed upon doping.