Highly polarized blue electroluminescence from homogeneously aligned films of poly(9,9-dioctylfluorene)

Abstract

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 ${\mathrm{(\lambda }}_{\mathrm{em}}\text{=458\hspace{0.17em}}\mathrm{nm}\mathrm{).}$ 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 ${\mathrm{cd/m}}^2.$