Photoluminescence and Electroluminescence of the Blue Emission of Devices Based on Poly (p-Phenylenevinylene) Copolymers

Bright blue polymer light-emitting diodes have been fabricated by using the poly(pphenylenevinylene)-based copolymers with 10 C long aliphatic chains as the electroluminescent layers, PBD in PMMA and Alq₃ as the electron-transporting layers, and aluminum as the cathode. The multilayer structure devices show 190cd/m² light-emitting brightness at 460nm, 15 V turn-on vol- tage. It is found that the intensities of photoluminescence and electroluminescence (EL) increase with increasing aliphatic chain length, the EL intensity and operation stability of these polymer light-emitting diodes can be improved by reasonable design of the structure.