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By performing first-principle quantum transport calculations, we investigated the effects of the edge types and edge defects on the electronic and transport properties of phosphorene nanoribbons (PNRs). The calculated band structures show the PNRs with the zigzag and cliff edges are all metallic. The conductance of the cliff phosphorene nanoribbon (CPNR) is higher than that of the zigzag phosphorene nanoribbon (ZPNR). The low bias negative differential resistance behavior is only found in the ZPNR and the peak-to-valley current ratio is up to 10 2 . More over, we found the carrier transport channels under low bias of ZPNR and CPNR mainly locate on the edges. The current-voltage characteristics show the defects induced by removing the phosphorus atoms from the edge can decrease the conductance of the ZPNR and CPNR obviously. The low bias negative differential resistance behavior of the ZPNR also can be weakened or removed by the edge defects. [ABSTRACT FROM AUTHOR]

By applying nonequilibrium Green's functions in combination with the density-functional theory, we investigate the electron transport properties of the salicylideneaniline molecule sandwiched between two armchair graphene nanoribbon (AGNR) electrodes. It shows that the width of the AGNR electrodes plays a significant role in the transport properties of the salicylideneaniline molecular junctions. The current–voltage characteristics of the salicylideneaniline molecule sandwiched between 8AGNR electrodes can perform a stable conductance switching behavior at the bias region [1.2 V, 1.6 V] when the molecule translates between the trans -enol form and the trans -keto form. When the electrodes change to 7AGNR, a remarkable negative differential resistance behavior can be found in the salicylideneaniline molecular device at the trans -keto form. That means the salicylideneaniline molecule can perform different functions when it connects to the different AGNR electrodes. [ABSTRACT FROM AUTHOR]