Efficient saturated red electrophosphorescence by using solution-processed 1-phenylisoquinoline-based iridium phosphors with peripheral functional encapsulation

A series of saturated-red emitting iridium complexes with bifunctional charge-transporting peripheral groups were designed and synthesized. The relationship between the structures and their photophysical, electrochemical and electrophosphorescent properties was investigated. Through the incorporation of hole-transporting triphenylamine units and/or electron-transporting phosphine oxide groups to the cyclometalating ligand, the new complexes exhibited good thermal stabilities with high glasstransition temperatures up to 284 degrees C, while maintained the saturated-red emission of the center core. Besides, the peripheries sufficiently protect the emissive core from the intermolecular interactions. Solution-processed single-layer phosphorescent organic light-emitting device (PhOLED) based on phosphor R2 showed a maximum external quantum efficiency of 7.6% with Commission Internationale de l'Eclairage coordinates of (0.68, 0.30). (C) 2015 Elsevier B.V. All rights reserved.