To meet the demands of ultra-high-definition displays, efficient and bright green organic light-emitting diodes (OLEDs) with a Commission Internationale de l'Éclairage (CIE) y-coordinate ≥ 0.7 are needed. While highly efficient devices based on pure-green multi-resonance emitters have been reported, efficiency roll-off and device stability remain challenges. This study presents the design of two pure-green multi-resonance emitters (ω-DABNA-M and ω-DABNA-PH) to create highly stable and efficient pure-green devices with CIEx,y coordinates close to NTSC and BT.2020 standards. Thermally activated delayed fluorescence (TADF) OLEDs using these emitters achieve CIEy up to 0.74. Hyperfluorescent device architectures further satisfy the CIE x-coordinate requirements for NTSC (0.21) and BT.2020 (0.17) while maintaining CIEy ~0.7. These hyperfluorescent devices exhibit maximum external quantum efficiencies (EQEs) exceeding 25%, maximum luminance over 10⁵ cd m⁻², suppressed roll-offs (EQE ~20% at 10⁵ cd m⁻²), and long device stabilities (LT95 ~600 h).
