NOVEL LIGHT-EMITTING DEVICES BASED ON PYRIDINE-CONTAINING CONJUGATED POLYMERS

We present novel light-emitting devices based on several pyridine-cont aining conjugated polymers and copolymers in various device configurat ions. The high electron affinity of pyridine-based polymers improves s tability and electron transport properties of the polymers and enables the use of relatively stable metals such as Al as electron injecting contacts. Bilayer devices utilizing poly(9-vinyl carbazole) (PVK) as a hole-transporting/electron-blocking polymer show dramatically improve d efficiency and brightness as compared to single layer devices. This is attributed to charge confinement and exciplex emission at the PVK/e mitting polymer interface. The incorporation of conducting polyaniline network electrode into PVK reduces the device turn-on voltage signifi cantly while maintaining the high efficiency. Two novel device configu rations that enable the use of high work function metals as electrodes are pointed out.