Interpolymer Self-Assembly of Bottom-up Graphene Nanoribbons Fabricated from Fluorinated Precursors

Abstract

Interpolymer self-assembly of bottom-up graphene nanoribbons (GNRs) has been realized by using fluorinated anthracene trimer precursors (HFH-DBTA) deposited onto heated Au(111) substrate. Whereas polymers derived from conventional precursor [10,10'-dibromo-9,9'-bianthryl (DBBA)] are adsorbed on Au(111) without apparent close packing, poly-HFH polymers derived from HFH-DBTA are densely self-assembled and require a long annealing time for cyclo-dehydrogenation because of the steric hindrance. First-principles calculations based on density functional theory revealed that the partially fluorinated edges of HFH-DBTA make molecular-substrate interaction weaker than that of DBBA, accelerate desorption, and leave islands of accumulated and locally aligned polymers. The partially fluorinated precursors also induce templating effects in interpolymer stacking because of H-F hydrogen bonding and F-F repulsion. The statistical analysis revealed that 84% of GNRs is parallel to the adjacent GNRs in the case of HFH-DBTA precursors. Field-effect transistors (FETs) were fabricated using such locally aligned multiple GNRs as channels. It has been found that on average, the on-current of the FETs is three times larger than that of FETs using less-aligned GNR channels made from the conventional DBBA precursors.

Stabilizing Edge Fluorination in Graphene Nanoribbons

“…The stability of 3b, the chevron-type fluorinated GNR synthesized in this work, is in contrast to previous attempts of synthesizing edge-fluorinated armchair GNRs using different anthracene derivatives as precursors. 16,24 In these cases, polymers were fully defluorinated before turning into GNRs. With the C−F bond being one of the strongest C−heteroatom single bonds, the premature cleavage was unexpected and attributed to a combination of surface and byproduct assisted bond weakening.…”

Band structure modulation by methoxy-functionalization of graphene nanoribbons

“…40,41 Functionalization of GNRs with cyano, fluoro, and amino groups has been reported through the on-surface method, but pre-installed functional groups are often removed during the cyclodehydrogenation on metal substrates, prohibiting efficient synthesis of edge-functionalized GNRs. [42][43][44][45] Through edge functionalization with electron-donating or -withdrawing groups, it becomes possible to modulate the electronic properties of GNRs, including the position of energy levels and bandgap. 42,43,[46][47][48][49] Moreover, the planarity of GNRs can also be altered by inducing steric repulsion.…”

One-Shot Synthesis of Peptide Amphiphiles with Applications in Directed Graphenic Assembly

“…Functional graphenic materials (FGMs) can be useful in biomedicine due to their biocompatibility, electrical conductivity, mechanical strength, and bioactive functionalization capacity . However, many of these desirable properties can only be realized in ordered structures, where graphenic sheets are aligned. − Few spontaneous, bottom-up assembly methods exist to arrange graphenic sheets into ordered 3D structures, and the types of architectures that can be accessed are limited. − …”