Synthesis and characterization of poly(terphenylenevinylene) derivative with electron withdrawing CN group and an electron donating alkoxy group

New poly(terphenylenevinylene) derivative with an alkoxy group and an electron withdrawing cyano group, poly(1,4-phenylene-2′-methoxy-5′-ethylhexyl-1′,4′-phenylene-1″,4″-phenylene-α-cyanovinylene), was synthesized via the Suzuki coupling reaction. The polymer was completely soluble in common organic solvent and showed good thermal stability up to 380 °C. The presence of the electron withdrawing cyano group lowered LUMO energy level and the presence of the electron donating alkoxy group increased HOMO energy level of the polymer relative to those of poly(terphenylenevinylene). Light emitting diodes (LEDs) with the configuration ITO/PTPCNV/Al and ITO/PPV/PTPCNV/Al were fabricated. ITO/PTPCNV/Al device showed turn on voltage of 5 V (0.005 mA), however, ITO/PPV/PTPCNV/Al exhibited turn on voltage of 2.5 V (0.003 mA). The maximum brightness of the ITO/PPV/PTPCNV/Al device is about 5200 cd/m2 at 8 V with a maximum efficiency of 1.243 lm/W. The EL spectrum of the ITO/PPV/PTPCNV/Al device, which was consistent with PL spectrum of PTPCNV, had a maximum peak at 491 nm with a shoulder peak at around 520 nm.