Influence of the dendron chemical structure on the photophysical properties of bisfluorene-cored dendrimers

Abstract

A detailed study of the photophysics of a family of bisfluorene-cored dendrimers is reported. Polarized time-resolved fluorescence, singlet-singlet exciton annihilation and fluorescence quantum yield measurements were performed and used to understand how the dendron structure affects the light-emitting properties of the materials. The exciton diffusion rate is similar in all films studied. An increase in the nonradiative deactivation rate by nearly one order of magnitude is observed in films of dendrimers with stilbenyl and carbazolyl based dendrons as compared to solutions, whereas the dendrimers with biphenyl and diphenylethylenyl dendrons showed highly efficient emission (photoluminescence quantum yields of 90%) in both solution and the solid state. The results of the materials that show fluorescence quenching can be explained by the presence of quenching sites at a concentration of just a fraction of a percent of all macromolecules. A possible explanation of this quenching is hole transfer from the emissive chromophore to the dendron in a face-to-face geometry. These results are important for the design of efficient blue emitters for optoelectronic applications.

Photophysical, amplified spontaneous emission and charge transport properties of oligofluorene derivatives in thin films

“…We found R 0 values of 1.2, 2.9 and 3.3 nm for the terfluorene, pentafluorene and heptafluorene, respectively, indicating that R 0 increases with the oligomer length. In good consistency with previous reports on exciton diffusion in fluorene derivatives, 35,39,[43][44][45] these results suggest that singlet excitons can diffuse in the oligofluorene films by a Fo ¨rster-type dipole-dipole coupling.…”

Solid-State Dendrimer Sensors: Probing the Diffusion of an Explosive Analogue Using Neutron Reflectometry

“…Light-emitting dendrimers are a relatively new class of fluorescent material that have been successfully developed for use in light-emitting diodes. [16][17][18][19] They consist of a core, dendrons, and surface groups *To whom correspondence should be addressed. ( with the latter being primarily responsible for their processability into thin films.…”

Theoretical investigation of the substituent effects on the electronic and optical properties of 6-substituted coumarin derivatives

“…To determine which coumarin derivative may be the optimal candidate for use as an optoelectronic material, it is necessary to understand the influence of the molecular structures on the electronic and optical properties [20][21][22].…”