A Class of Auxiliary Passivators for Polymer Dielectrics

Abstract

High‐electrical‐strength polymer dielectrics are essential for advanced devices with high power and/or high integration densities and film capacitors with high energy‐storage densities. Key factors affecting the polymer dielectric electrical strength are deep‐level defect states, which lead to electron and hole accumulation. Numerous deep‐level defect states lead to charge accumulation in the polymer dielectric during operation, contributing to local electric field distortion and resulting in flashover or breakdown. In this work, first‐principles calculations and experiments reveal that VH (i.e., H vacancies) in the polymer dielectric molecular chain can create defect states deep in the bandgap. RCl (R = Li, Na, K) can be used for passivating the deep‐level polymer dielectric defect states. In addition, the passivation mechanisms are analyzed. The RCl cations can passivate deep‐level defect states into shallow‐level acceptor defect states because the RCl dipole moment regulates the deep‐level defect state energy. The RCl anions can passivate deep‐level defect states into shallow‐level donor defect states by forming a stable covalent bond between carbon and lone‐pair electrons. This work supports the design of high‐electrical‐strength polymer dielectrics.

Polymer Dielectrics with Outstanding Dielectric Characteristics via Passivation with Oxygen Atoms through C–F Vacancy Carbonylation

“…First, we calculated the ideal PTFE through orbital-projected density of states (DOS) and partial charge density calculations (as shown in Figure a and Figure S32, Supporting Information) and found that no deep traps appeared. Although we observed the presence of deep traps in the experiment, previous studies found that the key indicator of deep traps in polymers is the appearance of vacancies. − Therefore, we simulated PTFE with F vacancies and labeled it defective PTFE. Our DOS and partial charge density results showed that it contained deep-level defect states in the bandgap (see Figure a,b), and the defect states were occupied by 0 electronic states; therefore, they were labeled occ0.…”

“…The reason for this problem is that these methods enhance electric strength by greatly changing the original material system without directly mitigating the root cause of the reduced electric strength of polymer dielectrics, that is, deep traps. Deep traps in polymer dielectrics directly affect their electric strength. − As localized states of electrons deep in the bandgap, deep traps are the accumulation centers of electron and hole carriers, resulting in a large amount of charge accumulation. − This causes local electric field distortion and triggers flashover and breakdown. − ,− Therefore, it is of great significance to develop a low-cost method that allows the large-scale direct regulation of deep traps in polymer dielectrics that perform stably after treatment.…”

“…The highest charge density decreased from −92.86 to −42.3 pC/mm 2 . The reduction in accumulated charge demonstrated effective deep trap passivation and a reduced risk of insulation failure in the material. − ,− Then, we tested the change in the flashover voltage. As shown in Figure f, the flashover voltage of PTFE after passivation treatment increased from 31.1 to 46.7 kV, an increase of 50.1%.…”

Self-assembled wide bandgap nanocoatings enabled outstanding dielectric characteristics in the sandwich-like structure polymer composites

“…The projector-augmented wave (PAW) approach was used to describe electron-ion interactions [51]. The generalized gradient approximation of the Perdew-Burke-Ernzerhof (PBE) functional and the Heyd-Scuseria-Ernzerhof (HSE06) hybridization function were employed for geometry optimizations and self-consistent static calculations, respectively [52][53][54][55][56]. Spin-orbit coupling (SOC) was considered.…”