A Novel Spiro[acridine-9,9′-fluorene] Derivatives Containing Phenanthroimidazole Moiety for Deep-Blue OLED Application.

Typical π-π stacking and aggregation-caused quenching could be suppressed in the film-state by the spiro conformation molecular design in the field of organic light-emitting diodes (OLEDs). Herein, a novel deep-blue fluorescent material with spiro conformation, 1-(4-( tert-butyl)phenyl)-2-(4-(10-phenyl-10 H-spiro[acridine-9,9′-fluoren]-2-yl)phenyl)-1 H-phenanthro[9,10- d]imidazole ( SAF-BPI), was designed and synthesized. The compound consists of spiro-acridine-fluorene (SAF) as donor part and phenanthroimidazole (BPI) as acceptor part. Owing to the rigid SAF skeleton, this compound exhibits a high thermal stability with a glass transition temperature ( Tg) of 198 °C. The compound exhibits bipolar transporting characteristics demonstrated by the single-carrier devices. The non-doped OLEDs based on the SAF-BPI as the emitting layer shows maximum emission at 448 nm, maximum luminance of 2122 cd m−2, maximum current efficiency (CE) of 3.97 cd A−1, and a maximum power efficiency of 2.08 lm W−1. The chromaticity coordinate is stable at (0.15, 0.10) at the voltage of 7-11 V. The device shows a slow efficiency roll-off with CE of 3.35 and 2.85 cd A−1 at 100 and 1000 cd m−2, respectively. [ABSTRACT FROM AUTHOR]