Tuning of the Electronic Properties of Armchair Graphene Nanoribbons through Functionalization: Theoretical Study of ¹Δ_g O₂ Border Addition

Abstract

We report the results of a DFT study of the border oxidation by (1) Δg O2 of molecular models of armchair graphene nanoribbons (a-GNRs). The aim of this work is to propose a new method, as an alternative or complementary method to the tuning of the size, to modify the electronic properties of a-GNRs. Here, we investigate modification of the HOMO and LUMO energies, which are some of the most important parameters to be controlled in the design of organic electronic devices. We study the oxidation reaction mechanism of medium-size polycyclic aromatic hydrocarbons, mimicking the stiffness and reactivity of a-GNRs. Thermodynamics and kinetics indicate that the reaction should bring about a decoration of the borders with vicinal dialdehyde groups. We also study the effect of this oxidation on the HOMO and LUMO energies of two series of molecular models of a-GNRs with increasing lengths. The results suggest that the oxidized a-GNRs should present LUMO energies lowered by 0.3-0.5 eV with respect to the original material, whereas the HOMO energies are barely lowered.

Tuning of the electronic properties of H-passivated armchair graphene nanoribbons by mild border oxidation: Theoretical study on periodic models

“…These trends of the frontier orbital energies confirm the results we obtained for the molecular models. In the previous work, we observed a cumulative effect on increasing the number of couples of vicinal dialdehydic groups. This effect was not fully additive and we presume this was due to the limited dimensions of the molecular models.…”

“…Because of the usage of molecular aromatic precursors, the latter techniques leads to the preparation of a ‐GNRs with all border sp 2 carbon bound to hydrogen atoms . In a previous work we have shown that the reaction of molecular models of these a ‐GNRs with singlet dioxygen ( 1 Δ g O 2 ) produces a decoration of their border with vicinal dialdheydic groups (Fig. ).…”

“…Tuning the energies of these orbitals is important because closely correlated with the electronic and optic properties of GNRs, all parameters to be controlled in the preparation of electronic devices . The intent of this work is to verify whether the functionalization by vicinal dialdehydic groups (the relative position of the two groups is a consequence of the mechanism) determines the lowering of the energy of the LUMO energy (and that of the HOMO) also on “infinite” periodic H‐passivated a ‐GNRs models. Such type of GNR and the computational method is the same used Barone et al The two approaches adopted in our previous study and in the present one will furnish information on these electronic properties of the two extreme situations: the large but finite molecular models and the periodic (i.e.…”