Electrical breakdown and charge dynamics of Polyethylene terephthalate films

Polyethylene terephthalate (PET) films have been used widely for capacitor application due to the high dielectric strength and low conduction loss. In this paper, we experimentally investigated the charge dynamics under the triangular voltage and temperature-dependent (TD) conduction of PET films up to the electrical breakdown using a specially designed conduction measurement setup. The charge dynamics in PET during transient voltage ramps as revealed by this setup provide implications of carrier transport with high mobility. In addition, the pre-breakdown conduction shows explicit space-charge-limited current features. The breakdown strength is stable in the temperature range from 25 to 100 °C and follows the derating process above 100°C. Also, a turning point is observed around the glass transition temperature for the nonlinear conduction onset field of PET films. The understanding of charged carrier behaviors at high electric fields can provide insights into the breakdown mechanism of dielectrics and the exploration of high-performance polymers.