▎ 摘　　要

Since graphene was successfully obtained in the end of 2004, the research on graphene and relevant devices has attracted extensive attention. The armchair- and zigzag-edge graphene nanoribbons, as the building blocks, are often used to design the graphene-based molecular electronic devices. Quinoline, an important intermediate between metallurgical dyes and polymers, is an organic conjugated small molecule which is simple in structure and easy to synthesize and modify the chemical structure, and quinoline has become one of the research focuses in the field of molecular electronic devices in recent years. From the physical point of view, the transport properties of the isomeric quinoline molecular electronic devices connected with graphene nanoribbon electrodes can provide a theoretical basis for designing and manufacturing molecular electronic devices with excellent performance. Based on the first-principles calculation method combining the density functional theory and non-equilibrium Green's function, this paper systematically investigates the transport properties of the carbon-linked isomeric quinoline molecule electronic devices sandwiched between the graphene nanoribbon electrodes. The obtained results show that the device current presents a linear change in a bias voltage range [-0.3 V, +0.3 V], the current decreases with the increase of the absolute bias voltage, separately, in a range of [+0.5 V, +0.8 V] and [-0.4 V, -0.9 V], demonstrating a strong negative differential resistance effect. On the other hand, the interesting negative differential resistance effect is remained when there is an angle between the quinoline molecular plane and the graphene nanoribbon electrode; the current of the device is found to be independent of the rotation direction of quinoline molecule in the central region; the current of the device should be forbidden when the quinoline molecule plane is rotated to a direction vertical to the graphene nanoribbon electrodes. The obtained results can provide a theoretical basis for designing and manufacturing the molecular switches and negative differential resistance devices based on isomeric quinoline molecular electronic devices.