Tetradentate Pt(II) Complexes with 6-Membered Chelate Rings: A New Route for Stable and Efficient Blue Organic Light Emitting Diodes

Abstract

Deep blue emitters are highly desired and intensively investigated for organic light emitting diodes for high quality full color display or solid state lighting applications. Here a new strategy for deep blue phosphorescent emission is demonstrated through the incorporaiton of 6-membered metal chelation rings in the tetradentate metal complex molecular structure. The platinum metal complex PtNON was synthesized and fully characterized. The emission spectra of PtNON shows a deep blue emission peaking at 438 nm at 77 K and a red-shifted, broadened, and structureless emission band centered at 508 nm at room temperature. The photoluminescent quantum yield of PtNON reaches a high value of 83%, and its luminescent lifetime remains as short as 3.76 μs in a 5% doped PMMA thin film. Organic light emitting diodes devices with PtNON as an emissive material were fabricated, achieving a peak device efficiency of 24.4% in a device structure designed for charge confinement. Furthermore, device architectures using known stable components with PtNON demonstrated an operational lifetime to 70% initial luminance estimated at over 30 000 h at 100 cd/m2 while also retaining moderate efficiencies over 10% despite the high triplet energy over 2.8 eV for the emitter.