In high-power-density chips and post-Moore's Law electronic devices, heat dissipation capability has become a critical factor affecting device reliability. Van der Waals heterostructures composed of two-dimensional materials, with their designable band structures and excellent electronic properties, are considered important candidate systems for next-generation integrated devices. However, their application has long been limited by insufficient thermal conductivity at the interfaces. When different 2D materials are stacked, the mismatch in lattice vibration modes (phonons) results in low thermal transport efficiency across the interface, with typical interfacial thermal conductance being only on the order of ~10 MW·m⁻²·K⁻¹, which is insufficient to meet the heat dissipation requirements of highly integrated devices. For a long time, the prevailing belief in the academic community was that introducing a twist angle between layers would disrupt lattice symmetry and enhance disordered scattering, thereby reducing interfacial thermal conductivity. Consequently, "twisting" was generally considered a factor that suppresses thermal transport.
However, recent research by a team has revised this understanding. The researchers constructed MoS₂/WS₂ bilayer heterostructures with different twist angles and systematically measured their interfacial thermal conductance. The results showed that as the twist angle increased from 0° to 38°, the interfacial thermal conductance increased from approximately 12 MW·m⁻²·K⁻¹ to approximately 30 MW·m⁻²·K⁻¹, an enhancement of about 2.5 times.
This phenomenon originates from a unique thermal transport mechanism at the heterogeneous interface. The study indicates that thermal conduction across the MoS₂/WS₂ interface is dominated by inelastic phonon scattering. At an untwisted interface, inelastic scattering already contributes about 55% of the interfacial thermal conductance; when the twist angle is approximately 21.8°, this contribution increases to about 70%. The introduction of a twist angle alters the phonon energy distribution at the interface, enabling high-frequency optical phonons to more effectively excite acoustic phonons on the opposite side through frequency conversion, thereby increasing heat transfer channels across the interface.
This also explains the differing effects of twist angle modulation between homogeneous and heterogeneous interfaces: Homogeneous interfaces typically rely on elastic scattering, and twisting introduces additional thermal resistance; whereas heterogeneous interfaces inherently depend on inelastic scattering, and twisting strengthens this dominant mechanism, thus resulting in enhanced thermal conduction.
On the experimental side, the team established a high-quality, large-area transfer process to fabricate structures with controllable twist angles ranging from 0° to 60°. By combining a high-throughput time-domain thermoreflectance (TDTR) mapping technique with neural network algorithms, they achieved spatial statistical measurement of interfacial thermal resistance, enhancing data reliability.
Based on these findings, the research team proposed a "perturbation-enhanced theory": In heterogeneous interfaces dominated by inelastic scattering, introducing interfacial perturbations such as twisting, sliding, or rippling can reconfigure the phonon energy distribution, thereby enabling a controllable increase in interfacial thermal conductance. This achievement provides a new physical picture for the thermal management of interfaces in 2D materials and offers a theoretical basis for the thermal management design of high-power electronic devices.