By applying nonequilibrium Green’s functions in combination with density-function theory, we investigate the effect of the weak intermolecular interaction on electronic transport properties in a bilayer graphene nanoribbon device. The results show that a successive switch behavior can be realized by adjusting the weak π–π interaction between two graphene nanoribbon molecules. Moreover, rectifying behavior can be observed in such systems. The mechanisms for these phenomena are suggested.Graphical abstractHighlights► The electronic transport properties in bilayer molecular devices are studied. ► The effects of the weak intermolecular interaction are considered. ► A successive switch behavior can be realized by adjusting the interaction. ► Rectifying behavior is induced by the intermolecular interaction.

Ballistic thermal transport properties at low temperatures in a quantum wire modulated with two coupling quantum dots are studied. The results show that when the temperature is low enough, the reduced thermal conductance displays monotonic behavior with the change of structural parameters; while at higher temperature, the reduced thermal conductance displays a nonlinear behavior. It is found that the phonon transmission and thermal conductance sensitively depend on the relative position of quantum dots and symmetric axis of the quantum wire. When the symmetry axis of quantum wire is away from the center of the quantum dots, the thermal conductance increases monotonously. It is also found that the thermal conductance can be modulated by the magnitude of the quantum dots and the length between the two quantum dots. Moreover, inhomogeneous quantum transport steps and quantized thermal conductance plateau can be observed in such structure.

Using a transfer matrix method, we study the properties of the localized plasmon modes in a semi-infinite semiconductor superlattice (SL) with cap layer. The results show that in such a structure there exist three localized plasmon modes. They may appear either in the gap between two bulk plasmon bands, or below and above the bulk plasmon bands. The evolution from the extended plasmon modes to the localized plasmon modes can clearly be tracked with the change of the structural parameters or the relative electron density. A brief analysis of these results is given. It is suggested that the localized plasmon modes can be artificially controlled by adjusting the parameters of the proposed micro-structures.

We investigate the thermal conductance in a quantum waveguide modulated with quantum dots at low temperatures. It is found that the thermal conductance sensitively depends on the geometrical parameters of the structure and boundary conditions. When the stress-free boundary conditions are applied in the structure, the universal quantum of thermal conductance can be found regardless of the geometry details in the limit T→0T→0. For an uniform quantum waveguide, a thermal conductance plateau can be observed at very low temperatures; while for the quantum waveguide modulated with quantum dots, the plateau disappears, instead a decrease of the thermal conductance can be observed as the temperature goes up in the low temperature region, and its magnitude can be adjusted by the radius of the quantum dot. Moreover, it is found that the quantum waveguide with two coupling quantum dots exhibits oscillatory decaying thermal conductance behavior with the distance between two quantum dots. However, when the hard-wall boundary conditions are applied, the thermal conductance displays different behaviors.

By applying nonequilibrium Green's functions in combination with density-functional theory, we investigate the effect of asymmetric electrode coupling on electronic transport properties in a Pyrene-based molecular device. The results show that rectifying behaviors can be tuned by changing the coupling degree between Pyrene molecule and electrode. Moreover, negative differential resistance behavior can also be observed in this model. The mechanisms for these interesting phenomena are suggested.Highlights► Electronic transport properties in molecular devices. ► Rectifying behavior induced by asymmetric electrode coupling. ► NDR can be modulated by controlling the matching of orbitals.