Molecular Orientation and Anisotropic Photoconduction of Evaporated Oligo-p-Phenylene Sulfide Films

Thin films of highly oriented oligo-p-phenylene sulfide (OPS) molecules have been prepared by vapor deposition. This proves that the chain axis of OPS molecules has a directional arrangement perpendicular to the substrate with a decrease in deposition rate. Parallel OPS molecules, which are uniaxially oriented along the rubbing direction of a substrate covered with a rubbed polymer thin film, can be obtained by evaporation with a higher deposition rate. Photocurrent measurements of uniaxially oriented films along the rubbing direction have indicated that OPS molecules are anisotropic in photoconduction, that is, carriers are more easily transported perpendicular to the molecular chain axis than along that axis.