Influence of mesoscopic ordering on the photoexcitation transfer dynamics in supramolecular assemblies of oligo-p-phenylenevinylene

The authors have studied the influence of mol. arrangement on the transfer rates of photoexcitations along supramol. assemblies of H-bonded oligo-p-phenylenevinylene (OPV) mols. for 2 different packing geometries, in view of optoelectronic device application. For well-defined, helical stacks of monofunctional OPVs fast (~50 ps) photoluminescence depolarization and excitation transfer to dopants was obsd., in agreement with semi-coherent exciton diffusion. For disordered assemblies of bifunctional OPVs incorporating a spacer to link adjacent mols., depolarization and energy transfer dynamics occur on a longer time scale (~nanosecond). This strongly suggests that such spacers need to be tuned carefully as they may otherwise interfere with the p-stacking thereby reducing the intermol. electronic coupling.