Phenanthroimidazole-Based Diphenylborane Dimers as Blue Emitters for OLEDs

Herein, the design and synthesis of π-conjugated diphenylboron-doped phenanthroimidazole dimers having intramolecular B–N coordination have been reported, along with their unique photophysical properties. The synthesized compounds exhibit bright blue fluorescence with high solution-state quantum yields reaching up to 99%, and they retain a 38% quantum yield in the solid-state thin films. Encouraged by excellent photophysical properties, we used diphenylboron-doped phenanthroimidazole dimers as blue emitters in the organic light-emitting diode (OLED) devices. The OLED devices with a host–guest emission layer having the diphenylboron-doped phenanthroimidazole dimer (blue emitter) as a guest emitter (20 wt %) in a 4,4′-bis( N -carbazoyl)-1,1′-biphenyl (CBP) host exhibited a high external quantum efficiency of 3.41% with current and power efficiencies of 4.53 cd/A and 1.75 lm/W and a maximum brightness of 2159 cd/m 2 . The deep blue electroluminescence (EL) emission corresponds to CIE ( x, y ) coordinates of (0.16, 0.16) and shows the potential of diphenylboron-doped phenanthroimidazole dimers as the efficient deep blue class of emitter molecules in blue OLEDs.