Charge Injection Barrier at the Metal/Oil-Paper Insulated Interface Based on First Principles

In order to elucidate the mechanism of charge injection from metal into insulators, a comparative study of charge injection in oil-paper systems is carried out using the first-principles calculation. In this work, the hole and electron injection barriers in the electronic structure of metal-dielectric and interface dipole are studied by using different interfaces, including metals such as aluminum and copper and dielectrics, such as mineral oil (MO), vegetable oil (VO), and cellulose kraft paper. The above interface was simulated by molecular dynamics and measured by density functional theory (DFT). The results show that the hole injection barrier is smaller than the electron injection barrier for all interfaces, which is in good agreement with the experimental results of insulation oil injection barrier measurement. Moreover, feasible dielectric models containing various chemical traps are measured.