Increasing the lifetime of polymer dielectrics in an AC field by using phosphorescent dopants: Theoretical justifications and numerical simulation

Abstract

Based on the ionization mechanism of polymer degradation in an AC field and taking into account the contribution of non-radiative carrier recombination, a new method for increasing the lifetime of polymers in the AC field is proposed. The polymer is doped with molecules of phosphorescent materials, such as complexes with metal atoms, which are characterized by a significant spin–orbit coupling. This removes the prohibition of phosphorescence of excited molecules and prevents the rupture of chemical bonds in macromolecules and the formation of free radicals. Polyethylene terephthalate, polymethyl methacrylate, polyvinylcarbazole, and polycarbonate were chosen as objects of study. Depending on the degree of increase in phosphorescence brightness, numerical calculations were performed to determine the lifetime (time interval before breakdown) of polymers in an AC field. Breakdown was defined as a sharp increase in charge concentration due to field ionization of macromolecules. Computer simulations have shown that as the contribution of non-radiative relaxation of triplet excitons decreases, the polymer lifetime in the AC field increases and tends toward the lifetime in the DC field.