Synthesis, optical properties, and electroluminescence of conjugated poly (p-phenylenevinylene) derivatives containing 1,3,4-oxadiazole and pyridine rings in the main chain

Three new poly(p-phenylenevinylene) derivatives-PO, POD, and POP-with oxadiazole and pyridine rings along the main chain were synthesized via Heck coupling. The polymers were amorphous and dissolved readily in common organic solvents. They showed relatively low glass-transition temperatures (up to 42 degreesC) and satisfactory thermal stability. Solutions of the polymers emitted blue-greenish light with photoluminescence (PL) emission maxima around 460 nm and PL quantum yields of 0.28-0.49. Thin films of the polymers displayed PL emission maxima at 461-521 nm, and their tendency to form aggregates was significantly influenced by the chemical structure. Light-emitting diodes with polymers PO and POP, with an indium tin oxide/poly(ethylenedioxythiophene) (PEDOT)/polymer/Ca configuration, emitted yellow and green light, respectively, and this could be attributed to excimer emission. (C) 2004 Wiley Periodicals, Inc.