Novel Multiple Resonance Type TADF Emitter as Blue Component for Highly Efficient Blue-Hazard-Free White Organic Light-Emitting Diodes

摘要

Realizing blue-hazard-free emission is an important goal for white organiclight-emitting diodes (OLEDs) toward healthy lighting applications. However,conventional blue organic emitters with broad emission spectra would generallycover the high-energy emission region and thus cannot meet the demand.Here a blue multiple resonance type thermally activated delayed fluorescence(TADF) emitter DPMX-CzDABNA is newly designed. The DPMX-CzDABNAbasedOLEDs can realize blue narrowband emission peaked at 484 nm with afull width at half maximum of 29 nm, and external quantum efficiencies (EQEs)around 26%, which allows DPMX-CzDABNA to precisely avoid the high-energyphoton contribution and thus be a promising blue component to constructhigh-performance white OLEDs with human-eye-friendly emission spectra.Using DPMX-CzDABNA and a reported TADF emitter BPPZ-DPXZ, respectively,as blue and orange components in white OLEDs, the single-emitting-layerdevices approach white emission with outstanding EQE up to 35.8%; thedouble-emitting-layer OLEDs achieve blue-hazard-free white emissions witha maximum EQE of 26.5% and very stable Commission Internationale del’Eclairage coordinates of ≈(0.38,0.43) over a wide luminance range from100 to 10 000 cd m~(?2). It is expected that this strategy can pave a new way fordeveloping highly efficient all-TADF white OLEDs without blue-hazard emission.