Facilitating triplet energy-transfer in polymetallayne-based phosphorescent polymers with iridium(III) units and the great potential in achieving high electroluminescent performances

A series orange phosphorescent copolymers with platinum(II) polymetallayne-based backbone have been successfully prepared through Sonogashira cross-coupling among bicarbazole moieties, 2-(naphthalen-2-yl)pyridine-based Ir^III phosphorescent units, and trans-[PtCl₂(PBu₃)₂]. The photophysical investigations have indicated highly efficient energy-transfer from both the singlet and high energy triplet states from the polymetallayne segments to the phosphorescent units in the copolymer backbone due to the proper energy-level matching fulfilled by the 2-(naphthalen-2-yl)pyridine-type ligands in the Ir^III phosphorescent units. Benefiting from these advantages, the phosphorescent polymers can furnish solution-processed phosphorescent OLEDs (PHOLEDs) with high EL efficiencies with current efficiency (η_L) of 8.35 cd A^-1, external quantum efficiency (η_ext) of 3.79% and power efficiency (η_P) of 2.25 lm W^-1, representing the very decent electroluminescent performances ever achieved by the orange phosphorescent copolymers. This work herein might not only provides a further study about the novel phosphorescent copolymers with platinum(II) polymetallaynes as backbone, but also provide valuable information for the design and synthesis of highly efficient phosphorescent copolymers.