Study on the electronic structures and transport properties of the polyporphyrin nanoribbons with different edge configurations

Combining the density functional theory with the non-equilibrium Green's function, three kinds of polyporphyrin nanoribbons (PPNRs) with different edge configurations have been considered: 1) all carbocyclic eight-membered rings (C8-Rs) located in edge are broken (M1); 2) all C8-Rs located in edge are perfect (M2); 3) partial C8-Rs located in edge are broken, subject to two kinds of configurations, as illustrated by M3 and M4. Calculation results indicate that the completeness of the C8-Rs can influence the electronic structures and transport properties of the nanoribbons. M1 is a nonmagnetic indirect semiconductor, while M2 and M3 are magnetic metals, M4 behaves as the bipolar magnetic semiconductor. Moreover, the spin-dependent transport properties of the two-lead devices based on PPNRs show that the significant spin-filtering effect can be realized in the device with partially broken C8-Rs in edge. Our results indicate that the PPNRs based devices would be suitable for spintronics devices.