Blue-hazard-free single-emissive-layer white organic LEDs based on an anti-quenching narrowband blue emitter

Abstract

Blue photons below 450 nm pose risks to visual health, while conventional lighting devices unavoidably emit in this region. Existing solutions often involve intricate emissive-layer designs or suffer from low efficiency. Here, we present blue-hazard-free single-emissive-layer white organic light-emitting diodes (WOLEDs) employing a newly developed multiple-resonance thermally activated delayed fluorescence (MR-TADF) emitter, BNCT, as an anti-quenching blue emitter and efficient energy donor. BNCT integrates a sky-blue MR-TADF core with a sterically hindered, electron-rich arylamine donor, effectively suppressing π–π stacking and aggregation-induced quenching while maintaining narrowband emission (486 nm, bandwidth = 26 nm) entirely above 450 nm. The finely tuned donor–acceptor interaction enables controlled charge-transfer characteristics and accelerates reverse intersystem crossing, ensuring efficient exciton utilization. When co-doped with yellow and red phosphorescent dopants in a single emissive layer, the resulting devices deliver balanced warm-white emission with CIE coordinates of (0.31, 0.44)–(0.40, 0.43), correlated color temperatures of 6013–4734 K, and negligible blue-hazard photon ratios (<0.2%). Remarkably, the devices achieve high efficiencies up to 27.8% external quantum efficiency. This work establishes a robust molecular design paradigm for anti-quenching MR-TADF emitters and advances the development of high-efficiency, eye-safe WOLEDs for next-generation healthy lighting and display technologies.

Keywords

blue-hazard-free lighting / multi-resonance thermally activated delayed fluorescence / organic light-emitting diode / single emissive layer

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