Study on deep trap states in polymers by photo-stimulated discharge based on the OPO laser

A photo-stimulated discharge (PSD) method is more effective than thermal methods to characterize the deep space charge traps in dielectric materials. In this paper, a new PSD measuring system was first built up based on the optical parametric oscillator laser. The laser can generate continuously tunable wavelengths whose range are 210420 nm and with average output pulse energy 2.3 mJ. The system overcomes the shortcoming of weak output energy in past experiments, especially in the range of ultraviolet band. The PSD current spectra of PET were measured by this system. The results show that the energy level of charge traps in the PET film is mainly distributed in 4.08∼5.18 eV, and the trap density maximum is at 4.22 eV. These data can provide the experimental basis for further research and improvement on electrical properties of materials.