Narrow Band Organic Emitter for Pure Green Solution-Processed Electroluminescent Devices with CIE Coordinate y of 0.77

While the development of solution-processed organic light-emitting diodes (sOLEDs) utilizing multiple resonance-induced thermally activated delayed fluorescence (MR-TADF) is highly significant, it is restricted by the limited solubility and film-forming property resulting from the rigid conjugate and planarity of MR-TADF materials. Herein, an effective strategy is presented to obtain solution-processed narrowband emitters by introducing an inert steric bulky hindrance group into the multiple resonance skeleton, thereby mitigating issues arising from intermolecular packing-induced poor solution processing ability and quenching effects. The resulting target emitter, designed as 3CzSF-BN, exhibits pure-green emission with a peak at 520 nm and a small full width at half maximum (FWHM) of 30 nm (0.14) eV. Remarkably, it achieves an exceptional photoluminescence quantum yield (PLQY) of 100% and notable advancements in solution processing attributes. The optimized bottom-emitting sOLED (BE-sOLED) device achieves an external quantum efficiency (EQE) over 20% with Commission Internationale de I'eclairage (CIE) coordinates of (0.214, 0.716). Notably, the top-emitting sOLED (TE-sOLED) device exhibits an ultra-pure green color with FWHM of 22 nm and CIE coordinates of (0.138, 0.771), thereby highlighting the effectiveness of this strategy in designing high-performance solution-processed MR-TADF materials. A solution-processible small-molecule multi-resonance thermally activated delayed fluorescence (MR-TADF) emitter is developed, and the resulting solution-processed organic light-emitting diodes (sOLEDs) exhibit maximum external quantum efficiency (EQE) over 20% with Commission Internationale de I'eclairage (CIE) coordinates of (0.214, 0.716). The top-emitting sOLED achieves a CIEy of 0.771 excessively close to the Broadcast Television 2020 (B.T.2020) standard. image