  The use of tris(bidentate) Ir(III) complexes as light active components in
phosphorescent organic light-emitting diodes (PhOLEDs) is currently the
state-of-the-art technology to attain long-lasting and highly performing
devices. Still, further improvements of their operational lifetimes are
required for their practical use in lighting and displays. Facial/meridional
stereoisomerism of the tris(bidentate) Ir(III) architectures strongly
influences their emissive properties and thereto their PhOLEDs performances and
operational device stabilities. This work underpins at the first-principles
level the different excited state reactivities of facial and meridional
stereoisomers of a series of tris(bidentate) Ir(III) complexes, which is found
to originate in the presence of distinct triplet metal-centered (3MC)
deactivation pathways. These deactivation pathways are herein presented for the
first time for the meridional isomers. Finally, we propose some phosphor design
strategies.
