Fast exciton diffusion in chiral stacks of conjugated p-phenylene vinylene oligomers -: art. no. 045203

The ultrafast dynamics of photoexcitations have been studied in chiral stacks of conjugated p-phenylene vinylene molecules functionalized with hydrogen-bonding groups. The results indicate that in solution, pi-pi interactions between the molecules give rise to fast exciton diffusion along the stacking axis of the assemblies. The chiral nature of the assemblies is found to cause a rotation of the dipole moment of excitons propagating along the stacks as indicated by time-resolved measurements of the photoluminescence polarization anisotropy. The observed exciton diffusion and energy relaxation dynamics in the molecular stacks are shown to be very similar to those found in conjugated polymer films. Moreover, it is demonstrated that through changes in the temperature of the surrounding solvent, the stacks can be dissociated reversibly as shown by a marked reduction in the diffusivity of excitons.