Electronic and Quantum Transport Properties of Heterobilayers of Graphene Nanoribbons and Zinc-Porphyrin Tapes

Using the first-principles calculation, we have shown that heterobilayers can be formed between armchair graphene nanoribbons (GNRs) and zinc-porphyrin tapes (Zn-PPTs). The PPTs investigated include triply lined (TL) and doubly linked (DL) PPTs. In addition, we have also investigated electronic structures and conductances of these heterobilayers. The bilayer involving the DL Zn-PPT is more stable than its TL correspondents due to stronger electronic coupling, which can be ascribed to the similar dispersion relations of the free-standing GNR and the DL PPT around the Fermi level. Consequently, the bilayer formation of TL Zn-PPT with GNR turns it into a metal, while its DL correspondent remains semiconducting but exhibits an increased on-current at an appropriate gate voltage. Our calculation of the band gap of the GNR as a function of the ribbon width also shows that the band-gap oscillation is reduced upon bilayer formation with DL Zn-PPT