Highly-twisted pyrene derivative for pure-blue organic light emitting diodes

Abstract

The new fluorescent blue host material, 1,3,6,8-tetrakis(2,5-dimethylbiphenyl-4-yl)pyrene (BD4PP), was synthesized for pure-blue organic light-emitting diodes (OLEDs). BD4PP has highly twisted and steric structure for efficient fluorescence, and has high thermal stability of 492 degrees C. BD4PP host doped with 5 wt. % 4,4'-bis(9-ethyl-3-carbazovinylene)-1,1'-biphenyl (BCzVBi) or 5 wt. % 1,4-bis[2-(3-N-ethylcarbazoryl)-vinyl]benzene (BCzVB) showed high device efficiencies due to wide bandgap ((similar to)3.1 eV) and electron-rich host. An OLED with the BD4PP:BCzVB emitter showed higher current and external quantum efficiencies 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). (C) 2019 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.