Space charge buildup and dissipation in charged polyimide films exposed to visible light
Résumé
Polyimide is photoconductive under visible light, whose blue component is strongly absorbed. A consequence of this absorption is to induce a heterogeneous conductivity within the film. We present space charge and surface potential measurements which provide evidence for a progressive motion of the charge distribution towards the back electrode, in good accordance with a simple model, assuming stability of the deposited charge, fast retrapping of the photoinduced carriers, as well as a conductivity proportional to light absorption. These results may suggest new ideas for characterization of the trapping structure and distribution of the space charge using different light wavelengths.