Ultrahigh Interfacial Thermal Conductance in Borophene Heterostructures Enabled by the Phonon Bridge

The rapid integration of nano- and microdevices underscores the critical role of interfacial thermal conductance (ITC) for effective heat dissipation, which is vital for device performance and stability. As an emerging two-dimensional (2D) material, borophene is a promising candidate for thermal management due to its excellent thermal and mechanical properties. In this study, we employ molecular dynamics simulations with machine learning potential to investigate the ITC of 2D borophene heterostructures formed by different edge orientations. Our results show that these heterostructures exhibit exceptionally high ITC values up to 6.46 GW m^-2 K^-1 at 300 K, surpassing most typical interfaces. This ultrahigh ITC result is primarily attributed to the substantial overlap in the phonon spectrum between two borophene polymorphs, which forms an ideal phonon bridge across the interface, as evidenced by their full-range phonon transmission. Since the matching of the phonon spectrum in the borophene heterostructures is inherently strong, we find that the variations of ITC values are significantly influenced by factors such as interfacial bonding and structural regularity induced by the edge orientations. Our analysis of steady-state atomic heat flux highlights the importance of bonding alignment, while calculations of Young's modulus confirm the influence of interfacial bonding strength. This work offers key insights into the thermal transport mechanisms across borophene heterostructures and thus paves the way for their applications in advanced thermal management technology.