Graphene/Chalcogenide Heterojunctions for Enhanced Electric-Field-Sensitive Dielectric Performance: Combining DFT and Experimental Study

TL;DR

This paper explores how combining graphene with chalcogenide materials improves the electric-field sensitivity of flexible dielectric composites, using both theory and experiments.

Contribution

The novel contribution is the use of graphene/TMD heterojunctions as fillers to enhance dielectric performance through interfacial electronic modulation.

Findings

Graphene/TMD heterojunctions show negative binding energy and significant interfacial charge redistribution.

The WS2-G/PDMS composite exhibited a 7.607% higher electric-field-induced voltage amplitude compared to pure PDMS.

Dielectric spectroscopy confirmed improved dielectric constants with stable loss trends in the composites.

Abstract

Electric-field-sensitive dielectrics play a crucial role in electric field induction sensing and related capacitive conversion, with interfacial polarization and charge accumulation largely determining the signal output. This paper introduces graphene/transition metal dichalcogenide (TMD) (MoSe2, MoS2, and WS2) heterojunctions as functional fillers to enhance the dielectric response and electric-field-induced voltage output of flexible polydimethylsiloxane (PDMS) composites. Density functional theory (DFT) calculations were used to evaluate the stability of the heterojunctions and interfacial electronic modulation, including binding behavior, charge redistribution, and Fermi level-referenced band structure/total density of states (TDOS) characteristics. The calculations show that the graphene/TMD interface is primarily controlled by van der Waals forces, exhibiting negative binding energy and significant interfacial charge rearrangement. Based on these theoretical results, graphene/TMD heterojunction powders were synthesized and incorporated into polydimethylsiloxane (PDMS). Structural characterization confirmed the presence of face-to-face interfacial contacts and consistent elemental co-localization within the heterojunction filler. Dielectric spectroscopy analysis revealed an overall improvement in the dielectric constant of the composite materials while maintaining a stable loss trend within the studied frequency range. More importantly, calibrated electric field induction tests (based on pure PDMS) showed a significant enhancement in the voltage response of all heterojunction composite materials, with the WS2-G/PDMS system exhibiting the best performance, exhibiting an electric-field-induced voltage amplitude 7.607% higher than that of pure PDMS. This work establishes a microscopic-to-macroscopic correlation between interfacial electronic modulation and electric-field-sensitive dielectric properties, providing a feasible interface engineering strategy for high-performance flexible dielectric sensing materials.

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