Outstanding high-temperature capacitive performance in all-organic dielectrics enabled by synergistic optimization of molecular traps and aggregation structures.

Abstract

Improving the high-temperature performance of polymer dielectrics is critical for the development of advanced electrical systems. The deterioration of the capacitive performance of polymer dielectrics at high electric fields and elevated temperatures is attributable to the exponentially increased conduction loss. Herein, a synergistic strategy of molecular trap and aggregation structure optimization is developed to suppress the conduction loss of polymer dielectrics. A molecular semiconductor - HAT-CN with high electron-affinity (EA) and special distribution of electrostatic potential is designed in this work. The theoretical calculation and experimental results show that HAT-CN can introduce electron traps and simultaneously interrupt the conjugation between aromatic rings in molecular chains via electrostatic interaction with polyetherimide (PEI). Consequently, the collective effect of electron trap and aggregation structure optimization reduces the leakage current density of PEI by nearly an order of magnitude at 200 °C and improves the mechanical properties of films. Finally, the HAT-CN/PEI all-organic composite achieves a discharge energy density of 3.8 J cm^-3 with efficiencies above 90% (U_η>90%) and long-term reliability over 100 000 cycles at 200 °C, outperforming most current polymer dielectrics. This work provides a new idea for the design of high-temperature polymer dielectrics based on molecularly engineered organic semiconductors.