Synthesis and properties of poly(p-phenylenevinylene-co-sulfonylene) for ablue light-emitting diode

Novel class of p-phenylenevinylene copolymer with sulfonylene group in the main chain (PPVS) was synthesized through the Wittig reaction of bis(bromom ethyl-p-phenyl)sulfone triphenylphosphonium salt with terephthaldehyde. PPV S was highly soluble in common organic solvents and showed strong blue-shif ted fluorescence because the polar sulfonylene group provided better solubi lity and limited pi-conjugation in polymer chain. A single layer device wit h PPVS sandwiched between indium-tin-oxide (ITO) and aluminum electrodes sh owed a blue electroluminescence (EL) peaked at 470 nm under the threshold v oltage of 14 V. HOMO and LUMO levels of PPVS were found to be 0.46 and 0.28 eV, respectively, lower than those of poly(p-phenylenevinylene) (PPV).