Review of thermal rectification experiments and theoretical calculations in 2D materials

Thermal rectification is a phenomenon similar to electrical rectification, which can actively regulate the heat flow. It exhibits high thermal conductivity in one direction, thereby effectively promoting the heat dissipation of electronic devices and the low thermal conductivity in the other direction to isolate the temperature and heat flux-sensitive components. The thermal rectification at the nanoscale has attracted wider attention as the size of electronic devices continues to decrease. Two-dimensional (2D) materials have special crystals with one atom thickness; hence, they have special 2D phonon transport properties. Compared with one-dimensional materials, it is easier to process asymmetric structures in the plane of 2D materials, and the achieved thermal rectification effect is generally better. This work reviews the theoretical calculations and the experimental work related to the thermal rectification of 2D materials and discusses the physical mechanisms involved. Furthermore, this review reports on the level of thermal rectification in the experimental and theoretical studies found in the literature and suggests directions for future thermal rectification research based on these results. Lastly, this review points out the possible applications of thermal rectification in the fields of intelligent thermal management, novel thermal transistors, and energy harvesting at the nanoscale.