Tetraphenylsilane‐Engineered MR‐TADF Emitters for Pure‐Green OLEDs with High‐Efficiency, Long Lifetime, and Gamut Close to BT.2020 Standard

ABSTRACT Achieving the concurrent combination of superior color purity, high efficiency, and long operational durability remains a formidable challenge for organic light‐emitting diodes (OLEDs), which are indispensable for realizing ultra‐high‐definition (UHD) displays. Herein, we propose a rational molecular design strategy that peripherally functionalizes the multi‐resonance thermally activated delayed fluorescence (MR‐TADF) skeleton with tetraphenylsilane (TPS) and deuterated TPS groups to address these challenges. The resulting emitters, p ‐DBFSi, m ‐DBFSi, and m ‐DBFSi‐d, exhibit sharp green emission (515–517 nm) with ultra‐narrow full‐widths at half‐maximum (FWHMs) below 0.070 eV, ranking among the narrowest green MR‐TADF materials reported. OLEDs employing m ‐DBFSi and m ‐DBFSi‐d as emitters deliver the purest green electroluminescence (CIE y = 0.76), extraordinary maximum external quantum efficiencies (EQE max ) of 40.1% and 41.9%, and maximum power efficiency (PE max ) approaching 200 lm W −1 , without employing an additional sensitizer, positioning them among the state‐of‐the‐art narrowband pure‐green OLEDs. Furthermore, the m ‐DBFSi‐d‐based device exhibits remarkably enhanced operational stability with operational lifetime (LT 80 ) of 2491 h at initial luminance of 1000 cd m −2 . Collectively, this work establishes a TPS‐ and deuteration‐engineered MR‐TADF strategy that enables OLEDs to combine ultra‐narrowband emission, outstanding efficiency, and exceptional durability, paving the way for next‐generation UHD displays.