49‐4: Highly Efficient and Stable Pure Green Phosphor‐Sensitized MR‐TADF Emitter for B.T.2020 Color Top‐Emission OLEDs

In this work, we report a novel green MR‐TADF emitter KHUGD by incorporating naphthalene units to the triazine acceptor, by attaching modified triazine acceptor to the para of MR core. The synthesized material exhibited a narrow FWHM of 22 nm within the pure green region. The optimized exciplex host assisted phosphor‐sensitized system with KHU‐GD emitter resulting in high EQE of 29.3% and an extended operating lifetime (LT 95 ) of 6,019 h at an initial luminance of 1,000 cd/m 2 . Furthermore, the fabricated top emission OLED with KHU‐GD showed pure green emission with narrow FWHM of 20 nm and corresponding CIE coordinates of (0.19, 0.76) approaching BT.2020 requirements.