Reduced Thermal Conductivity in SnSe Moiré Superlattices.

Two-dimensional (2D) materials with inherently low thermal conductivity offer significant advantages for thermal management due to constrained phonon transport. The introduction of rotational degrees of freedom in layered 2D materials to form Moiré superlattices enables precise modulation of material properties, including electronic band gaps and phonon scattering mechanisms. While simulations have demonstrated that twisted multilayer Moiré structures can significantly reduce thermal conductivity through enhanced scattering and localized phonon modes, experimental progress has been limited due to challenges in synthesizing multilayer superlattices. In this study, we report the in situ synthesis of SnSe nanosheets with twisted multilayer Moiré structures using a scalable chemical vapor deposition method. These superlattices, exhibiting multiple Moiré periods, achieve a significant reduction in thermal conductivity compared to regular multilayer structures, driven by enhanced phonon scattering, lattice mismatch, and localized phonon modes. This work establishes multilayer Moiré superlattices as a promising and scalable platform for engineering low thermal conductivity 2D materials for advanced energy and electronic applications.