Tuning transport properties of deformed carbon nanocages by electric field, electrode material, and type of coupling

Abstract

In this paper, we study the structural, electronic, and quantum transport properties in the smallest fullerene, C20, and the most famous fullerene, C60, and their corresponding fulleranes, C20H20 and C60H60. The molecules are attached to cumulene and graphene nanoribbon (GNR) electrodes. We examine the factors affecting electron transport in carbon molecular bridges, such as the application of an electric field, and changes in the type of and position electrodes. We first perform structural and electronic calculations with density functional theory (DFT), then we introduce the tight-binding parameters of the system for studying the transport properties of it, with the help of the non-equilibrium green's function (NEGF) method. Our findings show that fullerane molecular bridges are always electrically insulator, but fullerene systems can be metal, semiconductor, or even insulator, depending on the position of connection points to the electrodes. Larger fullerene molecular bridges, such as C60, are more chemically stable and can be used as molecular nanoelectronic devices. Besides, by applying an electric field to the C20H20 cage, we observe a phase transition from the semiconductor to the metal.