Hierarchical Traps Modulated Charge Transport of Dielectric Polymers toward Enhanced Breakdown Performance

Abstract

Charge carrier dynamics of trapping, detrapping, and transport dominate the electrical performance of dielectric polymers, which are vital for high-voltage equipment and electronic devices. The rich inhomogeneities in polymeric structure are manifested as distinct microphase crystallization regions, of which the contribution to charge dynamics remains as an unresolved frontier in dielectric physics, forming obstacles in designing high-performance dielectric polymers. Herein, we reveal the microscopic origin of inhomogeneity-generated intramolecular trap distributions and its modulation in charge transport. We find that under customized gradient branched structures, the generated rich deep traps build ordered trap blocks, forming hierarchical distributed energy levels where trap energy and density gradually decrease from the deepest trap block toward both chain terminals. We clarify that such a hierarchical configuration results in short-range transport of charge carriers, preventing energy accumulation from hopping through long-range free paths, leading to 12.5% enhanced breakdown performance of 701.1 kV/mm, as compared to the corresponding random copolymers. The proposed charge transport mechanism and intramolecular structure are expected to be utilized for developing next-generation dielectric polymers and customizing their electrical performance.