Giant Thermal Rectification from Single-Carbon Nanotube-Graphene Junction.

We describe the influence of the geometry parameters on the thermal rectification of single-carbon nanotube-graphene junction. The two-dimensional (2D) distribution of the thermal rectification with respect to the tube length and the side length of the graphene nanosheet are calculated and visualized. The maximum thermal rectification ratios of the designed single-carbon nanotube-graphene junction can reach 1244.1% and 1681.6% at average temperatures of 300 and 200 K, respectively. These values are much higher than those reported for single-material nanostructure-based thermal rectifiers. The thermal rectification ratios of the nanotube-graphene junction are fairly sensitive to geometry size and are almost entirely dominated by the degree of overlap of the power spectra under negative thermal bias. These findings could offer useful guidelines for the design and performance improvement of thermal diodes.