Highly Robust CuI-TADF Emitters for Vacuum-Deposited OLEDs with Luminance up to 222 200 cd m-2 and Device Lifetimes (LT90) up to 1300 hours at an Initial Luminance of 1000 cd m-2

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 (LL)-L-1 ' CT(Cz -> PzIPr/PyIPr*) excited states across the blue to red regions with exceptional radiative rate constants of 1.1-2.2x10(6) s(-1). Vapour-deposited OLEDs based on these Cu-I emitters showed excellent external quantum efficiencies and luminance up to 23.6 % and 222 200 cd m(-2), respectively, alongside record device lifetimes (LT90) up to 1300 h at 1000 cd m(-2) under our laboratory conditions, highlighting the practicality of the Cu-I-TADF emitters.

Automated summary

This article introduces a new type of copper compound emitter that exhibits high quantum efficiency, brightness, and long lifetime under experimental conditions, which is of great significance for advancing the practical application of copper-based organic light-emitting diodes.