Cyclometalated Platinum Complexes with Luminescent Quantum Yields Approaching 100%

A new class of cyclometalated tetradentate platinum complexes of the type Pt­[N/\C–O–LL′] was synthesized and characterized. N/\C is a cyclometalating ligand such as phenyl-pyrazole (ppz), phenyl-methylimidazole (pmi), or phenyl-pyridine (ppy), and LL′ is an ancillary ligand such as phenoxyl-pyridine (popy). The complexes in this series are highly luminescent, emitting blue to green light in solution with quantum efficiencies ranging from 0.39 to 0.64 and luminescent lifetimes from 2 to 9 μs. When doped in a poly­(methyl methacrylate) (PMMA) thin film, measured quantum efficiencies increase to 0.81–0.97 with lifetimes ranging from 4.5–10.4 μs. One notable example, the metal complex PtOO3, emits green light with a luminescent quantum efficiency approaching 100% and achieves approximately 100% electron-to-photon conversion efficiency in device settings.