The impact of organic light emitting diodes (OLEDs) in modern life is
witnessed by their wide employment in full-color, energy-saving, flat panel
displays and smart-screens; a bright future is likewise expected in the field
of solid state lighting. Cyclometalated iridium complexes are the most used
phosphorescent emitters in OLEDs due to their widely tunable photophysical
properties and their versatile synthesis. Blue-emitting OLEDs, suffer from
intrinsic instability issues hampering their long term stability. Backed by
computational studies, in this work we studied the sky-blue emitter FIrpic in
both ex-situ and in-situ degradation experiments combining complementary,
mutually independent, experiments including chemical metathesis reactions, in
liquid phase and solid state, thermal and spectroscopic studies and LC-MS
investigations. We developed a straightforward protocol to evaluate the
degradation pathways in iridium complexes, finding that FIrpic degrades through
the loss of the picolinate ancillary ligand. The resulting iridium fragment was
than efficiently trapped "in-situ" as BPhen derivative 1. This process is found
to be well mirrored when a suitably engineered, FIrpic-based, OLED is operated
and aged. In this paper we (i) describe how it is possible to effectively study
OLED materials with a small set of readily accessible experiments and (ii)
evidence the central role of host matrix in trapping experiments.Comment: 13 pages, 6 figure