Tunable Hybridization Between Electronic States of Graphene and Physisorbed Hexacene

Abstract

Non-covalent functionalization via physisorption of organic molecules provides a scalable approach for modifying the electronic structure of graphene while preserving its excellent carrier mobilities. Here we investigated the physisorption of long-chain acenes, namely, hexacene and its fluorinated derivative perfluorohexacene, on bilayer graphene for tunable graphene devices using first principles methods. We find that the adsorption of these molecules leads to the formation of localized states in the electronic structure of graphene close to its Fermi level, which could be readily tuned by an external electric field in the range of ± 3 eV/nm. The electric field not only creates a variable band gap as large as 250 meV in bilayer graphene, but also strongly influences the charge redistribution within the molecule-graphene system. This charge redistribution is found to be weak enough not to induce strong surface doping, but strong enough to help preserve the electronic states near the Dirac point of graphene. Our results further highlight graphene's potential for selective chemical sensing of physisorbed molecules under the external electric fields.

Molecular Dipole-Driven Electronic Structure Modifications of DNA/RNA Nucleobases on Graphene

“…The ability to detect biologically important molecules (such as DNA and RNA) in a sensitive, selective, and cost-effective manner is playing an increasingly important role in numerous fields such as medicine, biology, forensics, and technology. − Graphene-based biosensors have attracted extensive attention in recent years as they exhibit a high potential of providing fast, label-free, and ultrasensitive detection of biomolecules and nanomaterials. − Graphene, owing to its unique structure and electronic properties, offers many new opportunities for detection and quantification of nucleic acid sequences in DNA and RNA as well as in whole DNA strand sensing. ,− Recently, numerous approaches have been proposed to achieve label-free real-time molecule-specific detection of DNA and RNA nucleobases with graphene. − Among these, electronic detection methods using graphene nanodevices and nanopore-based architectures are the most promising . Despite their potential, there are still many issues that need to be solved before these approaches can be implemented in real applications, particularly due to a lack of fundamental understanding of graphene–nucleobase interactions and the origin of measured molecular fingerprints.…”

Graphene-enhanced Raman scattering on single layer and bilayers of pristine and hydrogenated graphene

“…It was shown that the substrate significantly affects the graphene layer 19,20 . The effects of the substrate may include doping 21 , strain 22 , and/or mixing of electronic states 23 . The easiest approach to study the effect of the substrate is a comparison of the behavior of single-layer graphene and turbostratic graphene bilayer on SiO 2 / Si substrate 24 .…”