Red to near-infrared electrophosphorescence from an iridium complex coordinated with 2-phenylpyridine and 8-hydroxyquinoline

An iridium complex coordinated with 2-phenylpyridine (ppy) and 8-hydroxyquinoline (q), ppy₂Irq, was synthesized and its thermal stability, absorption, photoluminescence, crystal structure and electrophosphorescence were characterized. The melting point of this material reaches as high as 374 °C and does not suffer decomposition upon heating at high vacuum therefore can be well sublimated. When ppy₂Irq was used as a guest emitting material in the electrophosphorescent device, the emission is 100% saturated red light starting at ∼600 nm, extending into the near-infrared region. The bathochromic shift, compared to the fluorescence and phosphorescence from Alq₃, Ptq₂ and Ir(ppy)₃, was analyzed to originate from the triplet excited state of 8-hydroxyquinoline ligand and the crystal structure analysis excludes the origin of π-π intermolecular interactions.