HETEROSTRUCTURE ELECTROLUMINESCENT DIODES PREPARED FROM SELF-ASSEMBLED MULTILAYERS OF POLY(P-PHENYLENE VINYLENE) AND SULFONATED POLYANILINE

Multilayer heterostructure thin films of electroactive polymers such as poly(p-phenylene vinylene) (PPV), -precursor and sulfonated polyaniline (SPAn), have been successfully fabricated by a process based on the spontaneous self-assembly of conjugated polyion on a substrate. We have prepared SPAn/PPV multilayer-heterostructure light-emitting diodes (LEDs) using this electrostatic self-assembly technique and discussed the electroluminescence (EL) properties. The thickness of each bilayer is about 20 Angstrom. The LED device composed of 10 bilayers has a turn-on voltage of about 1.4 V and greenish-yellow light was clearly observed under normal room illumination even at low driving voltage. These results are discussed in terms of radiative recombination of the singlet polaron-excitons formed by injection of electrons and holes and the formation of polaron-excitons in PPV layers of SPAn/PPV heterostructures.