Spiro-functionalized Ligand with Supramolecular Steric Hindrance to Control π−π Interaction in the Iridium Complex for High-Performance Electrophosphorescent Devices

Supramolecular steric hindrance (SSH) originates from the combination of the steric hindrance effect of rigid and bulky three-dimensional (3D) moieties with a weak supramolecular interaction. Orthogonally bulky spirobifluorene as a π−π stacking SSH model was incorporated into a homoleptic Ir complex. Ir(SFP) 3 with SSH exhibits impressive higher quantum yields and spectral stability than that of its alkyl-substituted counterpart Ir(BFP) 3 . The lower turn-on voltage and higher optimized dopant concentration for Ir(SFP) 3 were observed in the proof-in-concept phosphorescent organic light-emitting diodes (PHOLEDs) exhibiting a higher maximum brightness ( L max ) of 35481 cd·m −2, η L of 44.3 cd·A −1, and η P of 34.8 lm·W −1 . The probable supramolecular architectures of dopant−dopant and host−guest interactions were proposed on the basis of molecular modeling.