Electron transport properties of boron- and nitrogen-doped polycyclic aromatic hydrocarbons and cyclophanes are investigated with the nonequilibrium Greens function method and compared to transport properties of the unsubstituted species. The aim of the study is to derive the effect of the heteroatomic defects on the conductance of nanographenes and to propose new effective ways for current control and design of carbon devices. Of special interest are the electrical current rectifying properties of asymmetrically doped nanographenes and cyclophanes, as well as the rectification mechanism. The mechanisms of donor-π bridge-acceptor and donor-σ bridge-acceptor rectification are used to explain the diode-like properties of asymmetrically doped nanographenes and cyclophanes. The electron-rich nitrogen and electron-poor boron heteroatoms introduce conductance channels within the highest occupied molecular orbital-lowest unoccupied molecular orbital gaps of the hydrocarbons and cyclophanes and significantly enhance the conductance. The combination of nitrogen and boron impurities in one polycyclic aromatic hydrocarbon leads to asymmetrical I/V curves. The rectification is further enhanced in the cyclophanes where the boron impurities are located in one of the layers and the nitrogen impurities in the other. Owing to the efficient separation of the donor and acceptor parts, a higher rectification ratio is estimated. The rectifying properties of the asymmetrically doped carbon materials are derived from the nonequilibrium Greens function theory. The main reason for the rectification is found to be the interaction of the external electric field induced between the electrodes with the molecular orbitals of the asymmetrically doped hydrocarbons.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films