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 (LT₈₀) 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.