Abstract
4-Fluorophenyl, phenyl or naphthyl substituted 9-alkylcarbazoles were synthesized by the multi-step synthetic route. The materials were characterized by elemental analyses, mass and 1 H NMR spectroscopy as well as by electron photoemission technique. These derivatives were tested for hole injecting and transporting layers in OLEDs with Alq 3 as the emitter. The 3-(1-naphthyl)-9-ethylcarbazole-based OLED exhibited the best performance with a turn-on voltage of ∼3 V, a maximal current efficiency of 0.85 cd/A and maximum brightness of 1270 cd/m 2 . The device was modified with PEDOT:PSS hole injection layer and demonstrated lower turn-on voltage of ca. 3.0 V, combined with a maximum brightness of 9524 cd/m 2 and a maximum photometric efficiency of ca. 5 cd/A. © 2012 Elsevier B.V. All rights reserved.