Role of high-frequency phonons in interfacial thermal transport across MoS2/black phosphorus interfaces

Abstract

Two-dimensional (2D) MoS2/black phosphorus (BP) van der Waals (vdW) heterostructures are promising platforms for nanoelectronic and optoelectronic devices, where efficient interfacial heat dissipation is essential for thermal reliability. In such systems, the interfacial thermal conductance (ITC) governs cross-plane heat removal across weakly bonded interfaces. Here, we employ molecular dynamics (MD) simulations to investigate phonon-mediated thermal transport across multilayer MoS2/BP interfaces and to systematically examine the effects of cross-plane strain, temperature and point defects on the ITC. At room temperature, the pristine MoS2/BP interface exhibits an ITC of 54.8 MWm−2 K−1. Spectral decomposition shows that although low-frequency phonons below 8 THz dominate the overall heat transport, phonons above 8 THz contribute approximately 27% of the total conductance, revealing a substantial high-frequency contribution beyond the conventional acoustic-phonon-dominated picture. Compressive strain strongly enhances the ITC, reaching 219.7 MWm−2 K−1, due to improved phonon spectral overlap and elastic compatibility across the interface. Increasing temperature results in an increase of the ITC to 69.0 MWm−2 K−1 through enhanced phonon delocalization and inelastic phonon scattering. Point defects further increase the ITC by up to 14%, with Mo and S vacancies more effective than P because of reduced elastic mismatch and strengthened interfacial phonon coupling. Frequency-resolved analysis reveals that the strain-induced enhancement is accompanied by an increase in the high-frequency contribution from 27% to 37%, demonstrating that optical phonons play a direct role under compression. In contrast, the temperature- and defect-induced enhancements arise predominantly from anharmonic delocalization and low-frequency acoustic spectral matching, respectively. These results establish a unified mechanistic framework linking phonon spectral overlap and elastic compatibility to interfacial thermal transport, and demonstrate that strain and defect engineering provide effective routes for tuning heat dissipation in 2D vdW heterostructures. © 2026 Elsevier Ltd.