Novel Electroluminescent Polymers with Fluoro Groups in Vinylene Units

Abstract

New electroluminescent polymers with fluoro groups in vinylene units, poly(p-phenylenedifluorovinylene) (PPDFV) and poly(2-dimethyloctylsilyl-p-phenylenedifluorovinylene) (DMOS−PPDFV), have been synthesized by GILCH polymerization. These polymers have been used as the electroluminescent (EL) layers in double-layer light-emitting diodes (LEDs) (ITO/PEDOT/polymer/Al). PPDFV shows photoluminescence around λmax = 580 nm (exciting wavelength, 410 nm) and yellow electroluminescence around λmax = 565 nm. DMOS−PPDFV shows PL around λmax = 495 nm and green EL around λmax = 540 nm. The current−voltage−luminance (I−V−L) characteristics of the polymers show turn-on voltages of 3.0 V approximately. Two fluoro groups were introduced on every vinylene units of poly(p-phenylenevinylene) (PPV) and poly(2-dimethyloctylsilyl-1,4-phenylenevinylene) (DMOS−PPV) to give PPDFV and DMOS−PPDFV in an attempt to increase the electron affinity of the parent polymer. It was found that the efficiency of PLED of DMOS−PPDFV was about 7 times higher than that of DMOS−PPV.