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Elucidating the Spatial Arrangement of Emitter Molecules in Organic Light‐Emitting Diode Films
Author(s) -
Tonnelé Claire,
Stroet Martin,
Caron Bertrand,
Clulow Andrew J.,
Nagiri Ravi C. R.,
Malde Alpeshkumar K.,
Burn Paul L.,
Gentle Ian R.,
Mark Alan E.,
Powell Benjamin J.
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201610727
Subject(s) - common emitter , phosphorescence , oled , molecule , materials science , biphenyl , radiative transfer , chemical physics , iridium , optoelectronics , chemistry , nanotechnology , fluorescence , optics , physics , biochemistry , organic chemistry , layer (electronics) , catalysis
The effect of varying the emitter concentration on the structural properties of an archetypal phosphorescent blend consisting of 4,4′‐bis( N ‐carbazolyl)biphenyl and tris(2‐phenylpyridyl)iridium(III) has been investigated using non‐equilibrium molecular dynamics (MD) simulations that mimic the process of vacuum deposition. By comparison with reflectometry measurements, we show that the simulations provide an accurate model of the average density of such films. The emitter molecules were found not to be evenly distributed throughout film, but rather they can form networks that provide charge and/or energy migration pathways, even at emitter concentrations as low as ≈5 weight percent. At slightly higher concentrations, percolated networks form that span the entire system. While such networks would give improved charge transport, they could also lead to more non‐radiative pathways for the emissive state and a resultant loss of efficiency.