Synthesis of novel fluorene-based poly(iminoarylene)s and their application to buffer layer in organic light-emitting diodes

Abstract

The fluorene-based poly(iminoarylene)s with triarylamine unit were simply synthesized from palladium-catalyzed polycondensation of 2,7-dibromo-9,9-di-n-alkyllfluorene with primary amines such as aniline and p-toluidine. The polymers with high molecular weight were obtained and were thermally stable. The HOMO levels of the polymers (−5.1 eV) were close to the work function of ITO. Organic light-emitting diodes (OLEDs) of the form ITO/polymer/TPD/Alq3/LiF/Al showed lower turn-on voltage (VT = 2.2 V), the enhanced efficiency, and the higher maximum luminance at the higher current density (PFA1: 12 370 cd/m2 at 427 mA/cm2) than those of the device without polymer (VT = 3.6 V, 5790 cd/m2 at 233 mA/cm2). It is expected that these polymers can be used as a buffer layer in OLEDs.