3,6-Bis(indol-1-yl)-9-phenylcarbazoles as electroactive materials for electrophosphorescent diodes
作者:J. Keruckas、J.V. Grazulevicius、D. Volyniuk、V. Cherpak、P. Stakhira
DOI:10.1016/j.dyepig.2013.07.020
日期:2014.1
Four derivatives of 3,6-bis(indol-1-yl)-9-phenylcarbazole were synthesized by Ullmann-type coupling including those having methoxy groups at the different positions. Thermal, optical and photophysical properties of the synthesized materials were studied. All the synthesized 3,6-bis(indol-1-yl)-9-phenylcarbazoles are capable of glass formation with the glass transition temperatures ranging from 77 to 95 degrees C. They exhibit high thermal stability with the 5% weight loss temperatures ranging from 393 to 459 degrees C. Photoluminescence spectra of the dilute solutions of 3,6-bis(indol-1-yl)-9-phenylcarbazoles are characterized by two well-resolved vibrational peaks at ca. 390 nm and 405 nm. The solid films of the materials also exhibit well-resolved vibrational peaks, however the wavelengths of the maxima are red-shifted by ca. 10 nm. 3,6-Bis(indol-1-yl)-9-phenylcarbazoles were tested in the single-layer organic light emitting diodes as active materials and in phosphorescent light emitting diodes as host materials of emitting layers in combination with Ir(Fppy)(3) as a guest phosphor. Blue single-layer electroluminescent and electrophosphorescent devices with current efficiencies of 3.7-4.1 cd/A and 10.8-12.6 cd/A respectively were fabricated. (C) 2013 Elsevier Ltd. All rights reserved.