A Deep‐Blue‐Emitting Heteroatom‐Doped MR‐TADF Nonacene for High‐Performance Organic Light‐Emitting Diodes**
Subeesh Madayanad Suresh, Le Zhang, David Hall, Changfeng Si, Gaetano Ricci, Tomas Matulaitis, Alexandra M. Z. Slawin, Stuart L. Warriner, Yoann Olivier, Ifor D. W. Samuel, Eli Zysman‐Colman
Abstract
Abstract We present a p‐ and n‐doped nonacene compound, NOBNacene, that represents a rare example of a linearly extended ladder‐type multiresonant thermally activated delayed fluorescence (MR‐TADF) emitter. This compound shows efficient narrow deep blue emission, with a λ PL of 410 nm, full width at half maximum, FWHM, of 38 nm, photoluminescence quantum yield, Φ PL of 71 %, and a delayed lifetime, τ d of 1.18 ms in 1.5 wt % TSPO1 thin film. The organic light‐emitting diode (OLED) using this compound as the emitter shows a comparable electroluminescence spectrum peaked at 409 nm (FWHM=37 nm) and a maximum external quantum efficiency (EQE max ) of 8.5 % at Commission Internationale de l’Éclairage (CIE) coordinates of (0.173, 0.055). The EQE max values were increased to 11.2 % at 3 wt % doping of the emitter within the emissive layer of the device. At this concentration, the electroluminescence spectrum broadened slightly, leading to CIE coordinates of (0.176, 0.068).