Efficient Deep-Blue Electroluminescence Employing Heptazine-Based Thermally Activated Delayed Fluorescence

We report an efficient deep-blue organic light-emitting diode (OLED) based on a heptazine-based thermally activated delayed fluorescent (TADF) emitter, 2,5,8-tris(diphenylamine)-tri-s-triazine (HAP-3DPA). The deep-blue-emitting compound, HAP-3DPA, was designed and synthesized by combining the relatively rigid electron-accepting heptazine core with three electron-donating diphenylamine units. Due to molecular structure intramolecular charge transfer characteristics, HAP-3DPA in solid state presented high photoluminescence quantum yield of 67.0% obvious TADF nature short lifetime 1.1 ?s. Most importantly, OLED incorporating exhibited emission Commission Internationale de l’Eclairage (CIE) coordinates (0.16, 0.13), peak luminance 10,523 cd/m?2, rather external efficiency 12.5% without any light out-coupling enhancement. This finding not only reports molecule, but also presents feasible pathway construct high-performance emitters devices skeleton.