Charge transfer complex induced confinement effect between organic semiconductor and polymer chains for enhancing high-temperature capacitive energy storage

Abstract

High-temperature polymer dielectrics, renowned for their ultrahigh power densities, robust voltage endurance, and remarkable reliability, present significant potential in optimizing the functionality of microelectronics and electrical power systems. Herein, to elucidate a notable correlation between the confinement effect induced by charge transfer complexes (CTCs) and the discharged energy density (U_e), a series of PI-based composites were synthesized, integrating organic semiconductors with diverse electron affinities. The density functional theory (DFT) simulations revealed that escaping from the CTCs required higher activation energy, besides, a more pronounced electron localization function was observed in the interfacial region between PI chain and F₆TCNNQ in comparison to pristine PI, PI/F₂TCNQ, and PI/F₄TCNQ. Consequently, the CTCs present in PI/F₆TCNNQ exhibit the greatest electron localization, significantly impeding electron transport within the composite. Furthermore, at 200 °C, the U_e for the PI/F₆TCNNQ composite remains notably high at 5.06 J cm⁻³ with an efficiency above 90 %, representing a 2.45-fold increase compared to that of pristine PI (2.03 J cm⁻³). The findings provide evidence for a positive correlation between the confinement effect induced by CTCs and the discharged energy density (U_e) of the composite materials at elevated temperatures, thus offering valuable insights for future investigations focused on all-organic dielectric composite materials.