Biphenylvinylene quinolinol derivatives and their light-emitting properties

A series of poly(p-phenylenevinylene) (PPV) type dyes: QoBp, QoBm, QpBp, and QpBm containing biphenyl (B) and 8-alkoxyquinoline (Q) moieties connected at either ortho (o) or para (p) position are synthesized for the application of organic light-emitting diodes. The structure design takes the advantages of the good luminescent property of biphenylvinylene and the electron transporting nature of quinolinol. Two polymeric materials: poly-QoBp and poly-QoAp were also prepared, whereas the biphenyl moiety of the latter was replaced by a para-hydroquinone (Ap) moiety. All compounds exhibited high thermal stability with T-d values exceeding 300 degrees C. A typical blue light device made with QoBp showed a turn-on voltage of 4 V, a maximal intensity of 2.30 x 10(3) cd/m(2) at 20 V, and a highest external quantum efficiency (EQE) of 0.43%. Devices of the polymers were made by doping into PVK. The device made with poly-QoBp exhibited a turn-on voltage of 9.5 V, and a maximal intensity of 360 cd/m(2) at 15 V. A white light device was made successfully by the combination of the blue emission of QoBp and the red emission of 2,3-bisindolyl-N-methylmaleimide. It showed a maximal intensity of 940 cd/m(2) at 15 V with a highest EQE of 0.14%.