Pulsed photoconductivity and current oscillations in poly(vinyl chloride)

Transient photocurrents in poly(vinyl chloride) films are shown to be due to photo‐injection of electrons from metallic cathodes. Most of the injected electrons are promptly trapped, but some drift across the sample to the anode under the influence of an external electric field. The mobility of these electrons, determined by transient photoconductivity techniques, is 4.7 ± 0.5 × 10−4 cm2/V‐sec at 27°C, and rises to 3.4 ± 0.5 × 10−3 cm2/V‐sec at 43°C, the measuring cell having been evacuated to a pressure of 10−6 torr at both temperatures. Diffusion of helium into the samples appears to decrease the electron, mobility. It is suggested that electron transport is correctly described by using an energy‐band model for intramolecular motion and an activated hopping model for intermolecular transfer. Oscillations observed in the transient photocurrents in the frequency range 103–105 Hz are attributed to electron avalanche formation at the anode, with photosuccessors.