Field-Induced Carrier Localization Transition in Dielectric Polymers

Area of Science:

• Materials Science
• Computational Chemistry
• Solid State Physics

Background:

• Organic polymers offer advantages like flexibility and cost-effectiveness for dielectric applications.
• Their use is limited by dielectric breakdown under high electric fields, a phenomenon lacking mechanistic understanding in polymers.
• Existing models for dielectric breakdown, often based on avalanche processes, do not fully explain polymer behavior.

Purpose of the Study:

• To investigate the mechanistic understanding of dielectric breakdown in polymers.
• To explore the impact of high electric fields on hot carrier dynamics and chemical damage in polyethylene.
• To develop a predictive method for screening polymers with high dielectric breakdown fields.

Main Methods:

• Utilized nonadiabatic quantum molecular dynamics simulations.
• Systematically studied the effects of varying electric fields on polyethylene.
• Analyzed hot carrier dynamics, electronic state localization, and resulting chemical damage.

Main Results:

• High electric fields induce localized electronic states at the polymer surface.
• A critical transition in electronic states was identified near the intrinsic breakdown field.
• Strong polaronic coupling, C-H vibrational resonance, and C-C bond breaking were observed, indicating severe chemical damage.

Conclusions:

• The identified polaronic localization transition is a key factor in polymer dielectric breakdown.
• This transition provides a mechanistic understanding and a potential predictive tool for polymer dielectric strength.
• The findings enable computational screening of dielectric polymers for enhanced breakdown resistance.