Charge transport properties of tubular boron cluster-based molecular junctions: a first-principles study

The electronic transport properties of molecular junctions based on four boron clusters, B₃₂, B₃₉, B₄₂, and B₄₅, that have tubular ground state structures were studied using first principles calculations and non-equilibrium Green's function simulations. Spin polarized calculations indicate that the charge transport properties are almost spin-independent at low bias voltages. In fact, only the junction based on B₃₉ exhibits the spin polarization effect, while the other open-shell cluster (B₄₅) shows no spin dependence due to its coupling with the electrodes. The calculated current-voltage characteristics show that the four types of molecular junctions have diverse functionalities, with the B₃₂ and B₃₉ junctions exhibiting current limiting features, while a clear negative differential resistance effect was found in the B₄₂ and B₄₅ junctions. These results suggest that molecular junctions based on boron clusters, which support rich geometrical and electronic properties, could serve as an important group of candidates for constructing functional molecular devices.