Shengbiao Li, Ping Zhao, Yanqin Huang, Tingcheng Li, Chao Tang, Rui Zhu, Lei Zhao, Quli Fan, Shiqiang Huang, Zushun Xu and Wei Huang
To improve efficiency, processibility and stability, three novel poly-(p-phenylene vinylenes) (PPV) derivatives (Pa,Pb, and Pc) with pendent 2,4-difluorophenyl and fluorenyl moieties were synthesized via Gilch reaction. Compared with those of PPV and MEH-PPV, the absolute quantum efficiencies of these polymers showed remarkable improvement (measured at 38.7, 37.2, and 20.3%, respectively), which can be attributed to the presence of twisted multi-aryl segments and fluorine atoms. TGA revealed that the inflexion temperatures of their thermal decomposition curves were above 400 °C. Double-layered electroluminescent (EL) devices with these polymers as light-emiting layers [ITO/PEDOT:PSS/Polymer/Ba/Al] showed peak emissions at 493/515, 503, 600 nm and maximum luminance of 2700, 450, and 4700 cd/m2 for Pa, Pb, and Pc, respectively, with onset voltages of about 4 V.