Blue light-emitting diodes from a meta-linked 2,3 substituted alkoxy poly(p-phenylenevinylene)

We report the fabrication of blue-emitting organic LEDs based on a soluble poly(p-phenylenevinylene) (PPV) copolymer, which takes advantage of both meta linkages and of an unusual substitution pattern (2,3) of the solubilising alkoxy chains onto the aromatic ring, in order to blue-shift the radiative emission. We recorded turn-on fields of ∼1.1 MV/cm and efficiencies up to 0.032 cd/A in sandwich structures utilising Ca cathodes and a plasma-treated indium tin oxide (ITO) anode, coated with a poly(3,4-ethylene dioxythiophene) transport layer. The 1931 Commission Internationale de LʹÉclairage (CIE) coordinates of the electroluminescence spectrum are (0.1881, 0.1812) without any filtering and (0.137, 0.0666), i.e., suitable for full colour displays applications, after filtering away the emission extending beyond 510 nm.