The photoelectret state in kapton polyimide film. II. The effect of intensity of illumination and the autophotoelectret state

The photoelectret state in Kapton polyimide film as a function of intensity of illumination has been investigated using visible light and ultraviolet radiation. Experiments were carried out both with as‐received and heat treated Kapton samples. The photoelectret charge is observed to increase with the intensity of illumination tending towards saturation which is in accordance with the reciprocity law. The nature of decay curves shows the presence of shallow and deep trap levels in Kapton. Ultraviolet radiations were found more efficient for photopolarization than visible light. Heat treatment results in reduction of photoelectret charge which may be due to the decrease in the number of traps owing to high temperature aging. The autophotoelectret state has also been investigated in Kapton. This study is useful for exploring the possibilities of using Kapton in electrophotographic process and solar energy conversion devices.