A critical step in advancing the practical application of copper-based organic light-emitting diodes (OLEDs) is to bridge the large gap between device efficiency and operational stability at practical luminance. Described is a panel of air-and thermally stable two-coordinate Cu I emitters featuring bulky pyrazine-(PzIPr) or pyridine-fused N-heterocyclic carbene (PyIPr*) and carbazole (Cz) ligands with enhanced amide-Cu-carbene bonding interactions. These Cu I emitters display thermally activated delayed fluorescence (TADF) from the 1 LL'CT(Cz!PzIPr/PyIPr*) excited states across the blue to red regions with exceptional radiative rate constants of 1.1-2.2 × 10 6 s À 1 . Vapourdeposited OLEDs based on these Cu I emitters showed excellent external quantum efficiencies and luminance up to 23.6 % and 222 200 cd m À 2 , respectively, alongside record device lifetimes (LT 90 ) up to 1300 h at 1000 cd m À 2 under our laboratory conditions, highlighting the practicality of the Cu I -TADF emitters.
The utilization of triplet metal‐metal‐to‐ligand‐charge‐transfer (3MMLCT) emissions of Pt(II) complexes having a large radiative decay rate is a promising strategy to develop efficient red and deep‐red emitters for practical organic light‐emitting diodes (OLEDs). The panel of robust luminescent dinuclear Pt(II) emitters described here features pyridine‐/pyrazine‐fused N‐heterocyclic carbene‐based cyclometalating ligands and ditopic bis‐µ2‐formamidinate bridging ligands. These complexes show intramolecular Pt–Pt distances of 2.85–2.87 Å, are thermally stable up to 446 °C, and display strong red and deep‐red 3MMLCT emission (604–689 nm) with emission quantum yields close to unity. Under laboratory conditions, red and deep‐red OLEDs with these complexes show high external quantum efficiencies (up to 21.3%) and prolonged operational lifetimes (LT97 up to 2446 h) at an initial luminance of 1000 cd m−2, highlighting the practicality of these dinuclear Pt(II) emitters in organic optoelectronics application.
A critical step in advancing the practical application of copper-based organic light-emitting diodes (OLEDs) is to bridge the large gap between device efficiency and operational stability at practical luminance. Described is a panel of air-and thermally stable two-coordinate Cu I emitters featuring bulky pyrazine-(PzIPr) or pyridine-fused N-heterocyclic carbene (PyIPr*) and carbazole (Cz) ligands with enhanced amide-Cu-carbene bonding interactions. These Cu I emitters display thermally activated delayed fluorescence (TADF) from the 1 LL'CT(Cz!PzIPr/PyIPr*) excited states across the blue to red regions with exceptional radiative rate constants of 1.1-2.2 × 10 6 s À 1 . Vapourdeposited OLEDs based on these Cu I emitters showed excellent external quantum efficiencies and luminance up to 23.6 % and 222 200 cd m À 2 , respectively, alongside record device lifetimes (LT 90 ) up to 1300 h at 1000 cd m À 2 under our laboratory conditions, highlighting the practicality of the Cu I -TADF emitters.
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