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.