Substituent-Directed Interception of Energetic Electrons in Poly(vinylidene fluoride)-Based Dielectric Film via p-π...

Poly(vinylidene fluoride) (PVDF)-based polymer dielectric films suffer intrinsic breakdown initiated by high-energy electrons. Prevailing approaches relying on passive charge confinement or physical barriers cannot prevent initial bond dissociation events. Herein, a molecular design strategy employing tailored monosubstituted naphthalene derivatives achieves active electron energy dissipation within PVDF matrices. Systematic substitution control reveals the competitive dynamics between deep electron trapping in low-lying p-π conjugated orbitals (enhanced by electron-withdrawing halogens) and sacrificial ionization promoted by electron-donating groups that reduce ionization energy. These mechanisms exhibit unexpected synergy rather than competition. The optimal system, 4-Br-1-NH₂Naph/PVDF, exploits this cooperative effect: the electron-donating amino group enables preferential ionization under high fields, consuming primary electron energy to generate stable cations that recapture secondary electrons, while the bromine substituent provides supplementary deep trapping. This dual-pathway interception suppresses breakdown initiation, achieving a high discharged energy density of 29.1 J cm^-3 in an all-organic PVDF composite and establishing a molecular roadmap for extreme-condition capacitive storage.