10.1021/acsami.7b15542.s001
Jake A. McEwan
Jake A.
McEwan
Andrew J. Clulow
Andrew J.
Clulow
Andrew Nelson
Andrew
Nelson
Ross D. Jansen-van Vuuren
Ross
D. Jansen-van Vuuren
Paul L. Burn
Paul L.
Burn
Ian R. Gentle
Ian R.
Gentle
Morphology
of OLED Film Stacks Containing Solution-Processed Phosphorescent Dendrimers
American Chemical Society
2018
solution-processed emissive dendrimers
phenylbenzimidazol -2-yl
poly
interface
tris
diffusion process
as-formed film stacks
neutron reflectometry measurements
sulfonate
host
OLED Film Stacks Containing Solution-Processed Phosphorescent Dendrimers Organic light-emitting devices
2018-01-22 21:06:48
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Morphology_of_OLED_Film_Stacks_Containing_Solution-Processed_Phosphorescent_Dendrimers/5811402
Organic
light-emitting devices containing solution-processed emissive dendrimers
can be highly efficient. The most efficient devices contain a blend
of the light-emitting dendrimer in a host and one or more charge-transporting
layers. Using neutron reflectometry measurements with in situ photoluminescence,
we have investigated the structure of the as-formed film as well as
the changes in film structure and dendrimer emission under thermal
stress. It was found that the as-formed film stacks comprising poly(3,4-ethylenedioxythiophene):polystyrene
sulfonate/host:dendrimer/1,3,5-tris(<i>N</i>-phenylbenzimidazol-2-yl)benzene
(where the host was deuterated 4,4′-<i>N</i>,<i>N</i>′-di(carbazolyl)biphenyl or tris(4-carbazol-9-ylphenyl)amine,
the host:dendrimer layer was solution-processed, and the 1,3,5-tris(<i>N</i>-phenylbenzimidazol-2-yl)benzene evaporated) had well-defined
interfaces, indicating good wetting of each of the layers by the subsequently
deposited layer. Upon thermal annealing, there was no change in the
poly(3,4-ethylenedioxythiophene):polystyrene sulfonate/host:dendrimer
interface, but once the temperature reached above the <i>T</i><sub>g</sub> of the host:dendrimer layer, it became a supercooled
liquid into which 1,3,5-tris(<i>N</i>-phenylbenzimidazol-2-yl)benzene
dissolved. When the film stacks were held at a temperature just above
the onset of the diffusion process, they underwent an initial relatively
fast diffusion process before reaching a quasi-stable state at that
temperature.