2021/07/16 by Masakazu Nagata, Hyukgi Min, Erika Watanabe +5
Engineering · Materials Science · #Organic Light-Emitting Diodes Research #Luminescence and Fluorescent Materials #Organic Electronics and Photovoltaics
paper · doi:10.1002/ange.202108283
Abstract Developing organic luminophores with unique capability of strong narrowband emission is both crucial and challenging for the further advancement of organic light‐emitting diodes (OLEDs). Herein, a nanographitic fused‐nonacyclic π‐system ( BSBS‐N1 ), which was strategically embedded with multiple boron, nitrogen, and sulfur atoms, was developed as a new multi‐resonance thermally activated delayed fluorescence (MR‐TADF) emitter. Narrowband sky‐blue emission with a peak at 478 nm, full width at half maximum of 24 nm, and photoluminescence quantum yield of 89 % was obtained with BSBS‐N1 . Additionally, the spin‐orbit coupling was enhanced by incorporating two sulfur atoms, thereby facilitating the spin‐flipping process between the excited triplet and singlet states. OLEDs based on BSBS‐N1 as a sky‐blue MR‐TADF emitter achieved a high maximum external electroluminescence quantum efficiency of 21.0 %, with improved efficiency roll‐off.