MICROSTRUCTURE OF THIN-FILMS OF PHOTOLUMINESCENT SEMICONDUCTING POLYMERS

The polymer chain distribution in solution-cast thin films of poly(2-m ethoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV) has been investigated by X-ray diffraction. The results show that regardless o f the solvent, chain orientation in cast films is anisotropic; the PPV backbones and the planes defined by the benzene rings within the PPV backbones are predominantly parallel to the film plane. When drop-cast from tetrahydrofuran (THF), the preferred solvent for preparation of MEH-PPV films with low threshold in gain narrowing experiments, this a nisotropy in chain orientation is more pronounced, and the crystallini ty is higher. (C) 1998 Elsevier Science Ltd. All rights reserved.