Photoconduction and electrical transport in polypropylene

The photoconduction of polypropylene was measured. Based on experimental results on photoconduction current (I_photo ) spectra, V-I characteristics, and the temperature dependence of I_photo, it was found that, at low applied field, photoconduction processes such as carrier injection and transport take place in localized states instead of the conduction band; at high applied field, the prebreakdown current results from the trapped electrons emitted into the vacuum level and drifting in microvoids in polypropylene. Therefore, the conduction band plays no role in conduction processes until breakdown