Hybrid filler-based thermal interface materials: heat transfer mechanisms and AI-guided predictive design

Efficient thermal management has become a critical challenge in next-generation electronic, optoelectronic, and energy storage devices, where increasing power densities and device miniaturization demand reliable dissipation of heat. Thermal interface materials (TIMs) play a vital role in enhancing heat transfer between heat-generating components and heat sinks for cooling electronic devices. However, conventional TIMs reinforced with a single type of filler often face limitations, including poor dispersion, discontinuous conductive pathways, and high interfacial resistance, leading to insufficient thermal conduction. Advanced hybrid filler systems have recently emerged as powerful solutions to these challenges by integrating multiple fillers with complementary geometries and properties, such as spherical particles, one-dimensional nanotubes or nano-rods, and two-dimensional nano-sheets. These hybrid architectures exploit synergistic effects, including improved packing density, enhanced phonon/electron transport pathways, and reduced void formation. The multiscale conductive networks enable more efficient thermal conduction while maintaining tunable mechanical and thermal properties. This review provides an in-depth investigation of the underlying heat transfer mechanisms in hybrid-filler systems, with emphasis on percolation synergy and phonon bridging. Furthermore, this study highlights design strategies for synergistic optimization and explores the broad range of applications of hybrid TIMs in high-performance electronic devices. In addition, this review further provides guidance on how to make use of artificial intelligence (AI) and machine learning (ML) for predicting of heat transfer mechanisms in composite materials and TIMs design.