Abstract：
It is a huge challenge to explore how charge traps affect the electric breakdown of polymer-based dielectric composites. In this paper, alkane and aromatic molecules with different substituents are investigated according to DFT theoretical method. The combination of strong electron-withdrawing groups and aromatic rings can establish high electron affinity molecules. 4\'-Nitro-4-dimethylaminoazobenzene (NAABZ) with a vertical electron affinity of 1.39 eV and a dipole moment of 10.15 D is introduced into polystyrene (PSt) to analyze the influence of charge traps on electric properties. Marcus charge transfer theory is applied to calculate the charge transfer rate between PSt and NAABZ. The nature of charge traps is elaborated from a dynamic perspective. The enhanced breakdown mechanism of polymers-based composites stems from the constraint of carrier mobility caused by the change in transfer rate. But the electrophile nature of high electron affinity filler can decrease the potential barriers at the metal-polymer interface. Simultaneously, the relationship between the electron affinity of fillers and the breakdown strength of polymer-based composites is nonlinear because of the presence of the inversion region. Based on the deep understanding of the molecular trap, this work provides the theoretical calculation for the design and development of high-performance polymer dielectrics.
摘要：
探索电荷陷阱如何影响聚合物基介电复合材料的电击穿是一个巨大的挑战。在本文中,根据DFT理论方法研究了具有不同取代基的烷烃和芳烃分子。强吸电子基团和芳香环的组合可以建立高电子亲和力分子。将垂直电子亲和力为1.39eV，偶极矩为10.15D的4'-硝基-4-二甲基氨基偶氮苯（NAABZ）引入聚苯乙烯（PSt）中，以分析电荷陷阱对电性能的影响。应用马库斯电荷转移理论计算PSt和NAABZ之间的电荷转移速率。从动态角度阐述了电荷陷阱的性质。聚合物基复合材料的增强击穿机制源于传输速率变化引起的载流子迁移率的约束。但是高电子亲和力填料的亲电性质可以降低金属-聚合物界面处的势垒。同时,由于存在反转区，填料的电子亲和力与聚合物基复合材料的击穿强度之间的关系是非线性的。基于对分子陷阱的深刻理解,本工作为高性能聚合物电介质的设计和开发提供了理论计算。
