Colour-Tunable Organic Light-Emitting Diodes with Single Pt (O^N^C^N)-dibenzofuran Emitter Exhibiting High External Quantum Efficiency of ∼30% and Superior Operational Lifetime.

Colour-tunable organic light-emitting diodes (CT-OLEDs) have a large colour-tuning range, high efficiency and operational stability at practical luminance, making them ideal for human-machine interactive terminals of wearable biomedical devices. However, the device operational lifetime of CT-OLEDs is currently far from reaching practical requirements. To address this problem, we designed a tetradentate Pt(II) complex named tetra-Pt-dbf, which can emit efficiently in both monomer and aggregation states. This emitter has a high T d of 508°C and a large intermolecular bonding energy of -52.0 kcal/mol, which improve its thermal/chemical stability. Our unique single-emitter CT-OLED essentially avoids the "colour-ageing issue" and achieves a large colour-tuning span (red to yellowish green) and a high EQE of ∼30% at 1000 cd m -2 as well as an EQE of above 25% at 10000 cd m -2 . We estimated a superior LT 90 operational lifetime of 520,536 hours at a functional luminance of 100 cd m -2 , which is over 20 times longer than the state-of-the-art CT-OLEDs. To demonstrate the potential application of such OLEDs in wearable biomedical devices, we fabricated a simple electromyography (EMG)-visualization system using our CT-OLEDs. This article is protected by copyright. All rights reserved.