Achieving a high dielectric constant and low dielectric loss of polymer composites filled with an interface-bonded g-C3N4@PbS narrow-bandgap semiconductor

Abstract

Scattering medium-bandgap semiconductors into polymers cannot remarkably improve the dielectric constant in composites. Nanoscale ceramic leads to a high interface leakage current. To obtain a high dielectric constant and low loss, in this work, graphitic carbon nitride (g-C3N4)@PbS microparticles were prepared for fabricating polymer-based ternary composites. Polymer/PbS binary composites were also fabricated. In terms of electric properties, ternary composites show more advantages than binary composites. In ternary composites, the improved dielectric constant is ascribed to SN bonding at the g-C3N4/PbS interface. Decreased dielectric loss is rooted in the reduced interface leakage current (from the large size of the hybrid filler) between the polymer and PbS. Under high fields, the reduced breakdown strength is attributed to the reduced bandgap in the hybrid filler compared with PbS and g-C3N4. The innovation of this work is the high-efficiency collaboration between microsized and interfacial SN bonding in g-C3N4@PbS filler. The ternary composite with 15 wt% hybrid filler has a high dielectric constant of ~ 39 and a low dielectric loss of ~ 0.04 at 100 Hz (low field) as well as a high breakdown strength of ~ 202 MV m−1 under a direct-current field. This work might enlighten the fabrication of polymer composites with great promise in energy storage.