Fluorophenyl and Trifluoromethylphenyl Terminal Groups: Enabling BT.2020‐Targeted Narrowband Green Emission in High‐Performance OLEDs

To meet the critical demand for ultra‐high‐definition (UHD) display technology, luminescent materials must achieve precise peak emission positions and narrow emission bandwidths simultaneously. Herein, we report a new class of narrowband pure green thermally activated delayed fluorescence (TADF) materials, DBNDO‐1, DBNDO‐2, and DBNDO‐3. These compounds are constructed on diborane‐embedded polycyclic aromatic hydrocarbon (PAH) skeletons fused with a dibenzo[ b,d ]furan motif. Through strategic incorporation of three distinct terminal substituents, 3,4,5‐trifluorophenyl, 4‐(trifluoromethyl)phenyl, and 3,5‐bis(trifluoromethyl)phenyl units, we further precisely modulate emission maxima while maintaining narrowband emission characteristics. All of these emitters exhibit bright green luminescence and narrowband emission characteristics, with luminescence peaks ranging from 513 to 518 nm. The full width at half maximum (FWHM) is only 14 to 16 nm in dilute toluene solution. Additionally, the photoluminescence quantum yields (PLQYs) for all of these emitters exceed 95%. The corresponding optimized OLEDs based on DBNDO‐1, DBNDO‐2, and DBNDO‐3 achieved peak external quantum efficiencies (EQE max ) of 33.7%, 32.4%, and 32.0%, respectively. The CIE y coordinates for these OLEDs were 0.74, 0.75, and 0.75, with FWHM values ranging from 18.5 to 19.4 nm. To the best of my knowledge, the EQEs, FWHM, and CIE y values represent some of the most exceptional performance metrics reported in the current literature.