Synthesis and properties of stable amorphous hole-transporting molecules for electroluminescent devices

New triphenylamine-carbazole end-capped molecules were synthesized by a divergent approach using bromination and Suzuki cross-coupling reactions. All compounds showed an excellent electrochemical reversibility and a good thermal stability. They were fabricated as hole-transporting layers (HTLs) with the device configuration of ITO/HTL/Alq3/LiF:Al. A bright green emission from the Alq3 layer with a maximum luminance of 7500 cd/m2 was observed at 9.8 V and a low turn-on voltage of 3.4 V.

The synthesis and characterization of new triphenylamine-carbazole end-capped molecules is reported. The double-layer OLED devices of these molecules with Alq3 exhibit bright green emission with a low turn-on voltage of 3.4 V.