Doping Effects in the Charge Transport of Graphene–Porphyrins

Abstract

Doping effects of B, N, and phosphorus (PHP) in graphene and of aza N in porphyrin of graphene–porphyrin (GP) complexes bonded through an amide group have been studied using density functional theory (DFT) and time-dependent DFT mainly at the M06/6-31G(d,p) level of theory. Structural, optical, electronic, and charge transport properties are analyzed for a set of eight GP complexes. We found that all GP complexes feature the characteristic absorption bands of porphyrin in the visible region, Q and Soret, showing P → P electronic transitions. Charge transfer between the fragments graphene and porphyrin in both directions P → G and G → P is obtained in the excited states, but the absorptions are of lower intensity when compared to the P → P ones. Doping only the graphene group of GP yields blue-shifted porphyrin absorptions; however, doping graphene and porphyrin yields red-shifted absorptions. Doping leads to a reduction of the HOMO–LUMO gap in all GP complexes, because the dopant atoms perturbation of the...