Design, Synthesis and Electroluminescent Properties of Multiresonant Thermally Activated Delayed Fluorescence Materials Based on Tetrahydroquinoline

Abstract

Multiresonant thermally activated delayed fluorescence (MR-TADF) materials are a series of hot materials to realize ultra-high definition organic light-emitting diode (OLED) display. 5,9-Bis(1,2,3,4-tetrahydroquinoline)-5,9-dihydro-5,9diaza-13b-boranaphtho[3,2,1-de]anthracene (THQBN) and 7-(tert-butyl)-5,9-bis(6-(tert-butyl)-4,4-dimethyl-1,2,3,4-tetrahydroquinoline)-5,9-dihydro-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracene (Tt-THQBN) were designed and synthesized as organoboron based MR-TADF based on tetrahydroquinoline, whose structures were characterized by nuclear magnetic resonance and mass spectrum. The thermal stabilities, electrochemical properties and photophysical properties of these two molecules were measured. They had the similar deep-blue photoluminescence, narrow full-width at half-maximum and high photoluminescence quantum yield with the classical MR-TADF molecules. OLED devices were fabricated employing THQBN and Tt-THQBN as the guest materials. They all had deep blue emission at 455～458 nm. The CIE-y values of devices 2～4 are less than 0.1, and the full width of half maximum (FWHMs) of all devices were narrow, whitin the range of 34～38 nm. Their maximum brightness can exceed 1000 cd•m -2 without serious efficiency roll-down. The device lifetime LT90 of device 3 with best performance in these devices can reach 99 h at the initial brightness of 1000 cd•m -2 .