Synthesis of electrochemically and thermally stable amorphous hole-transporting carbazole dendronized fluorene

A novel amorphous hole-transporting carbazole dendrimer, 2,7-bis[3,6-di(carbazol-9-yl)carbazol-9-yl]-9,9-bis-n-hexylfluorene (G2CF), was synthesized by a divergent approach involving bromination and Ullmann coupling reactions. G2CF showed UV-vis absorption bands at 304 and 332 nm in chloroform solution and the photoluminescence spectra showed a maximum peak at 373 nm in a bluish-purple region. Differential scanning calorimetry (DSC) and cyclic voltammetry (CV) analysis revealed G2CF was an electrochemically and thermally stable amorphous material with a high glass transition temperature (T-g) of 237 degrees C. The organic light-emitting device having the structure of ITO/G2CF/Alq(3)/LiF:Al exhibited a bright green emission with a maximum luminescence of 11,000 cd/m(2) at 16 V and a turn-on voltage of 5.4 V. (c) 2006 Elsevier B.V. All rights reserved.