Homogeneous alignment of poly(9,9-dioctylfluorene) films on thin layers of rubbed precursor-route poly(p-phenylenevinylene) allows the construction of light-emitting diodes that emit highly polarized blue light (λem=458 nm). The rubbed poly(p-phenylenevinylene) acts as an effective hole-injecting alignment layer. Annealing of poly(9,9-dioctylfluorene) in its nematic phase followed by rapid quenching orients the polymer as a glassy monodomain on the alignment layer and gives devices with a polarization ratio of 25:1 and a luminance of up to 250 cd/m2.

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We present a new synthetic approach to both phenylquinoxaline polymers and low molar mass glasses. A palladium-catalyzed coupling of arylalkynes and bromobenzenes and subsequent oxidation of the triple bonds lead to the corresponding benziles. Reaction with diaminobenzidine yields poly(phenylquinoxalines) (PPQs), whereas the reaction with 1,2-diaminobenzenes leads to low molar mass bis(phenylquinoxalines) (BPQs) and tris(phenylquinoxalines) (TPQs). Both PPQs and TPQs carry tert-butyl or CF3− substituents and are fully soluble in chlorinated hydrocarbons. The starburst TPQs are able to form stable, low molar mass glasses. Cyclic voltammetry reveals that the TPQs have low-lying lowest unoccupied molecular orbitals levels at about −3.6 eV and are attractive as electron-transport materials in organic light-emitting diodes (LEDs). Two-layer LEDs with poly(phenylenevinylene) were fabricated that show a maximum brightness of 450 cd/m2.

Polarized light over a large spectral region is provided by the novel procedure described in this work. The active material of these light‐emitting diodes (LEDs) is formed by two polymer layers that are oriented perpendicularly to each other. The orientation is obtained using the rubbing technique combined with thermal annealing. The Figure represents the electroluminescence (EL) emission from the two‐layer LED and its structure (see also inside front cover).