Molecular Orientation and Photoconduction of Polyimide

The effect of the molecular orientation on photoconduction of polyimide was investigated. The anisotropy of the molecular chain alignment was observed by wide-angle X-ray diffraction. The photocurrents in three directions were measured. The in-plane photocurrents were anisotropic. As Kapton was drawn, the molecular chain had a tendency to arrange itself along the drawing direction and the in-plane photocurrent in the direction normal to the drawing direction was larger than that in the parallel direction. As the degree of intermolecular order decreased, the photocurrent in the normal to the film plane increased; however, the in-plane photocurrent decreased. It was concluded that the magnitude of the photocurrent is closely related to the molecular chain alignment and the orientation.