High dielectric polyimide composite film filled with a heat-resistant organic salt

Abstract Thin film dielectric materials with high dielectric constant and high heat resistance are imperatively demanded for the miniaturization of electronic devices. In this work, we designed a novel homogeneous polymer composite film featuring both high dielectric constant and high heat resistance by adopting an organic salt of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). In detail, the organic salt LiTFSI was directly blended with polyamic acid (PAA, the precursor of polyimide (PI)) followed by film-casting and thermal imidization, yielding the composite film of PI/LiTFSI. The PI/LiTFSI composite film containing 15 wt.% LiTFSI exhibited excellent comprehensive performance including a high dielectric constant of 8.44, a low dielectric loss of 0.12 (1 kHz), a breakdown strength of 107.9 kV/mm, a 5% weight loss temperature (T 5% ) of 453.8 °C, a glass transition temperature (T g ) of 265.2 °C, and a tensile strength of 195.5 MPa. The PI/LiTFSI composite film will apparently have application prospect as a substitute for high-temperature dielectric materials.