Rigid Oxygen‐Bridged Boron‐Based Blue Thermally Activated Delayed Fluorescence Emitter for Organic Light‐Emitting Diode: Approach towards Satisfying High Efficiency and Long Lifetime Together

• DOI: 10.1002/adom.202000102
• Publication Date: 2020-04-01T09:58:02Z
• Authors: Dae Hyun Ahn; Jee Hyun Maeng; Hyuna Lee; Hanjong Yoo; Raju Lampande; Ju Young Lee; Jang Hyuk Kwon
• Keywords: Quantum Efficiency; Quantum yield; Phosphine oxide

Abstract Thermally activated delayed fluorescence (TADF) materials have emerged as an efficient emitter for achieving high efficiency of blue organic light emitting diodes (OLEDs). However, it is challenging to satisfy both device and long operational lifetime together. Here, highly electrochemically stable TADF emitter, 5‐(5,9‐dioxa‐13b‐boranaphtho[3,2,1‐de]anthracen‐7‐yl)‐10,15‐diphenyl‐10,15‐dihydro‐5H‐diindolo[3,2‐a:3′,2′‐c]carbazole (DBA‐DI) designed synthesized OLED. This exhibits photoluminescence quantum yield 95.3%, small single‐triplet energy gap 0.03 eV, short exciton 1.25 µs, bond dissociation (BDE). Also, phosphine oxide free triplet host systems (single mixed) blocking layer are analyzed using molecular optical simulations find system with BDE suitable emission zone OLEDs. The fabricated OLED DBA‐DI exhibited a maximum external (EQE) 28.1% CIE color coordinates (0.16, 0.39) (LT 50 ) 329 h at the initial luminance 1000 cd m −2 . Furthermore, mixed host‐based showed slightly lower EQE 26.4% almost two times longer : 540 h) than single device.