Exciton Trapping in an Organic Dendrimer Possessing No Energy Gradient

The optical properties of a novel triarylamine dendrimer system are reported. The dendrimer is composed of triarylamine dendrons and a diphenylbenzidine core. Excitations are transferred from the mostly delocalized triarylamine dendrons to the diphenylbenzidine core with a lifetime of 25 ps and 95% yield via a exciton−phonon coupling mechanism rather than the more typical Förster-type mechanism. This work implies that energy traps with over 95% efficiencies can be engineered into triarylamine systems by the addition of biphenylene linkages.