Synthesis of Novel Fluorene-Based Poly(iminoarylene)s and Their Application to Buffer Layer in Organic Light-Emitting Diodes

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/Alq 3 /LiF/Al showed lower turn-on voltage ( V T = 2.2 V), the enhanced efficiency, and the higher maximum luminance at the higher current density (PFA1: 12 370 cd/m 2 at 427 mA/cm 2 ) than those of the device without polymer ( V T = 3.6 V, 5790 cd/m 2 at 233 mA/cm 2 ). It is expected that these polymers can be used as a buffer layer in OLEDs.