Synthesis of Highly Twisted Pyrene Derivative for Pure Blue OLED

Abstract

We synthesized new fluorescent blue host material, BD4PP for pure-blue OLEDs. BD4PP has highly twisted and steric design for efficient fluorescence, and showes high thermal property of 492 oC. BD4PP host doped with 5 wt. % 4,40-bis(9-ethyl-3-carbazovinylene)-1,10-biphenyl (BCzVBi) or 5 wt. % 1,4-bis[2-(3-N ethylcarbazoryl)- vinyl]benzene (BCzVB) showed high device efficiencies based on wide bandgap (~3.1 eV) and electron-rich host. An OLED with the BD4PP:BCzVB emitter presented higher current and external quantum efficiencies (EQEs) of 4.41 cd/A and 3.80% with color coordinates (0.16, 0.13) compared to those of the BD4PP:BCzVBi (3.63 cd/A and 3.62%) with color coordinates (0.16, 0.11) and non-doped BD4PP (2.01 cd/A and 1.61%) with color coordinates (0.18, 0.13). In other words, BD4PP molecule inhibited the intermolecular interaction, resulting in color purity and high efficiency by introducing xylene units into the structure.