Premium
Control of Electrophosphorescence in Conjugated Dendrimer Light‐Emitting Diodes
Author(s) -
Lupton J. M.,
Samuel I. D. W.,
Frampton M. J.,
Beavington R.,
Burn P. L.
Publication year - 2001
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/1616-3028(200108)11:4<287::aid-adfm287>3.0.co;2-z
Subject(s) - phosphorescence , materials science , chromophore , dendrimer , electroluminescence , miscibility , dopant , oled , photochemistry , optoelectronics , diode , quenching (fluorescence) , polyfluorene , chemical physics , fluorescence , doping , polymer , nanotechnology , optics , chemistry , polymer chemistry , composite material , physics , layer (electronics)
We present a novel platinum porphyrin based phosphorescent dendrimer for use as a triplet harvesting dopant in organic light‐emitting diodes. Two types of dendritic host materials are used. Through the choice of a common branching architecture around the emissive chromophore unit of both guest and host materials, we are able to achieve excellent miscibility. The relative contribution of guest to host emission is found to depend strongly on the energy level offsets of the two blend materials, indicating strong trapping processes. Under pulsed operation, we observe a striking dependence of the emission spectrum on pulse period, independent of the host material used. This spectral modification is attributed to the quenching of triplet excitations at high excitation densities. We find excellent agreement between our measured data and a model based on bimolecular recombination.