Photoelectrical properties of oriented polyimide films

The steady photocurrents of polyimide (PI) film samples were measured. It is shown that the dark currents of PI films vary with drawing ratios, but their steady photocurrents are almost the same. In addition, the decay curves of the photocurrents change significantly with drawing ratios. It is suggested that the variation of structure during drawing or stretching may give rise to the variation of the trap structures which affect carrier transport in drawn PI films. The method of photostimulated current is used to study the variation of trap depth resulting from stretching of drawn PI films. The effect of line intensity on photoconductivity is also investigated