Fluorescence and host-guest energy transfer in polymeric chains

Intrachain singlet electronic excitation energy transfer from host polyvinylcarbazole (PVCa) to guest vinylbenzocarbazole (VBCa) units has been studied through measurements of the quenching effect on PVCa fluorescence and observation of the sensitized guest VBCa emission in solutions at 293 and 77K for different intramolecular concentrations of guest VBCa units. A method of taking into account intrinsic traps of singlet excitons (excimer forming sites, EFS), ordinarily present in an impurity free polymer macromolecule, has been elaborated. The comparison of the experimental data with theory shows that the one-dimensional singlet excitation energy transfer in a polymeric chain involves motion of incoherent excitons randomly hopping to a nearest neighbor along the line under conditions when capturing occurs upon the first visit of a trap and trapping centers of different origin become indistinguishable as regards their capturing capability.