They observed little change in the photoluminescence
(PL) efficiency between devices with micron-sized domains
to nanometer-sized domains indicating almost no
change due to charge dissociation and therefore attributed
the improvement in EQE of their ink-jetted devices to improved
charge transport. Ink-jet printed devices likely have
finer phase separation because solvent drying rates are
more rapid in ink-jet printing due to the small volumes
of liquid (100 pL) being dispensed, allowing for less time
for the polyfluorene blend components to phase-separate.